Photocatalytic remediation of Congo red and Pharmacological properties of Solidago canadensis L.mediated biogenic synthesis of ZnO Nanoparticles

Photocatalytic remediation of Congo red and Pharmacological properties of Solidago canadensis L.mediated biogenic synthesis of ZnO Nanoparticles | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Photocatalytic remediation of Congo red and Pharmacological properties of Solidago canadensis L.mediated biogenic synthesis of ZnO Nanoparticles Lokesh Kumar Tripathi, Rishendra Kumar This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7267346/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract In this study, biogenically mediated Sc -ZnO nano-sized particles were produced via leaf extract of S. canadensis L. of the Asteraceae Family and characterized through sophisticated techniques. Optical analysis through UV- vis . spectroscopy revealed formation of Sc -ZnO NPs with peak at 372 nm with calculated bandgap of 3.42 eV. Further, FTIR produced clear signals of participation of phytochemicals. Morphologically, aggregated flaky-structures and elemental composition was revealed through FESEM + EDS and the average size was deduced by TEM. XRD fallouts determined crystal structure of zinc oxide and the average crystallite size of 20.94 nm was deduced. The antibacterial potential and MIC against bacterial pathogens were analysed employing disc-diffusion method and micro-broth dilution assay respectively. Antioxidant potential and IC 50 of the fabricated ZnO was analysed using DPPH assay. Furthermore, the application of fabricated nanoparticles was studied for the photocatalytic degradation of Congo-red. We observed 91.2% degradation efficiency with a first-order rate of reaction of -k = -0.0398. The fabricated Sc-ZnO nanoparticles proved effective degradation of hazardous textile effluents with potential antibacterial nature. Photocatalysis Antibacterial Antioxidation MIC XRD HR-TEM FTIR SEM-EDS Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Introduction Azo dyes have been recognized as a colouring agent and its toxicological adversities ( Mcyotto et al. 2021 ). Congo-red (CR) is a di-azo water-soluble dye (C 32 H 22 N 6 Na 2 O 6 S 2 ) that includes two (-N = N-) groups composed of a sodium salt of benzidinediazo-bis-1-naphthylamine-4-sulfonic acid ( Tara et al. 2020 ). With a linear symmetry, a molecule of CR contains a hydrophobic centre comprised of two phenyl rings linked with di-azo bonds ( Yates & Yates, 2016 ). With the phenyl rings, two terminally charged naphthalene moieties containing sulfonic and amino groups are attached. Due to the presence of di-azo in the chemical structure, CR imparts a characteristic red colour in basic solution and red in acidic solution and forms an amine component; benzidine; due to cleavage of azo groups ( Clavijo & Osma, 2019 ) . According to the (NCBI, 2025) , benzidine is recognized as a potent bladder carcinogen and other studies have implicated to activate accumulation of platelets, thrombocytopenia, and circulated micro-embolism, thus, included in the banned category of azo dyes ( Siddiqui, et al. 2023 ). CR is been utilized in textile-dying, colour-cosmetics, pigments, leather-tanning, food-processing, pharmaceuticals, paper and wood-pulp industries and its all-embracing usage have added to the environmental pollution ( Yakupova et al. 2019 ). Previous publications disclose attempts at physical processes such as adsorption, biodegradation, and a few chemical processes utilizing chlorination and ozonation approaches ( Modi et al. 2022 ). Since, environmental contamination of CR has a wide range of consequences for natural resources, it is critical to develop new methodology for CR remediation ( Haleem et al. 2024 ). CR have multiple functional groups, rigidly bonded to the substrate that hinders the degradation process. Therefore, an advanced oxidation process (AOP) is utilized to eliminate the soluble dyes that are difficult to treat with conventional techniques ( Khan et al. 2024 ). The photocatalysis AOP, is a potential approach for oxidizing organic contaminants. Photocatalysis, employs UV light and catalysts to accelerate the breakdown of azo dyes ( Pavel et al. 2023 ). Green nanoparticles have been observed to increase in a variety of sectors, including chemical science, environment, biotechnological fields ( Dangana et al. 2023 ). Zinc oxide nanoparticles, among other nano-sized materials, are utilized as auxiliary source of pollutant deterioration because of their high UV light absorption ( Saad Algarni et al. 2022 ). ZnO has a comparatively eclectic band gap of 3.37eV and 60meV of exciton energy has been employed as an efficient photocatalyst for producing reactive oxygen species (ROS) that decompose several pollutants of organic nature ( Albiss & Abu-Dalo, 2021 ) . Conventional methods namely, physical and chemical strategies were employed to synthesize nanoparticles (Amin et. al.; Verma et al. 2023 ). Since hazardous substances utilized in the synthesis of NPs, the limitations of conventional approaches cannot be avoided ( Saad Algarni et al. 2022 ) In contrast, the green synthesis approach has gained tremendous attention past decade for the synthesis of ZnO NPs that overcome the utilization of hazardous chemicals ( Tiwari et al. 2024 ). Furthermore, the green synthesis process was created to eliminate any environmentally harmful compounds. The availability of phenolics, flavonoids, and alkaloids, plant extract-mediated nanoparticles have been exploited for a variety of pharmacological and environmental applications ( Fowsiya et. al. 2016 ). These phytochemicals reduce, cap and stabilize during synthesis of metallic oxides, generating surface to volume ratio for dye degradation ( Ostovar et al. 2023 ). These NPs also have potential antimicrobial and antioxidation activity due to stringent effect of phytochemicals capped to the surface of NPs ( Tiwari et al. 2024 ). With this regard, this study is aimed towards biogenic zinc oxide synthesis using aqueous infusion of an invasive plant Solidago canadensis L. This species belongs to the Asteraceae family and together with other family members has been extensively studied for phytochemicals as well as invasive compounds. We characterized the formed Sc -ZnO NPs and analysed for antimicrobial, antioxidant activity and further the photocatalytic activity and kinetics against Congo-red dye are evaluated. Methods and Materials Zinc acetate dihydrate and Congo Red was procured from CDH, India; while, DPPH, Ciprofloxacin, Sterile discs, Nutrient Agar, Muller-Hinton Broth, and, SDB was procured from Hi-Media, India, while microbial cultures were procured from MTCC, IMTECH, Chandigarh. Collection of Plant Material The leaves of Solidago canadensis L. were collected from the slopy grasslands of Bhimtal region, (29.35°N longitude and 79.5667°E latitude), during the flowering season (October to mid-November). S. canadensis L. is an invasive species and does not belong to the IUCN list of endangered species. For the taxonomic identification, (processed by Dr. S.K. Singh), herbarium voucher was prepared with intact flowers and was accessioned at (BSD Student Herbarium) at the office of the Botanical Survey of India (BSI), Northeren Regional Centre, Dehradun, India, with ID number (BSI/NRC HERB (Ident.)/2022-23/1004), and accension number (1305) was obtained. Preparation of S. canadensis L. Aqueous Extracts ( Sc- aq.ex.) The aerial parts were collected and shipped to lab in zip-lock bags. After thoroughly cleaning with distilled water the leaves were shed-dried for a week, then powdered and sieved. 10 grams were assorted with Millipore water in 1:10 ratio respectively and heated at 65°C for 30 min in a heated stirrer. Next, this solution was brought to moderate temperature (25°C) and centrifugated at 3000 g for 5 min to isolate the supernatant containing the dissolved phytochemicals. The filtrate was then filtered using Whatman no.1 and collected for storage until further use at 4°C. Preparation of Sc -ZnO Nanoparticles For Sc- aq.ex. mediated biogenic synthesis of ZnO nanoparticles, 50 ml of Zinc acetate dihydrate solution (0.2 mM) was stirred in a magnetic shaker for 30 min. To this salt solution, 1 mL of Sc aq. ex., was added dropwise and allowed to form a homogeneous mixture. This mixture was further stirred for 1 hr followed by the adjustment of pH to approx. 12 using (0.2 M) NaOH, for the reaction to complete, thus, forming a white precipitate. The reaction mixture was further aged in dark for 48 hrs ( Fig. 1 ) . Next, the settled white precipitate was washed thrice with ultrapure water using a centrifuge at 10,000 g for 10 min and finally with absolute ethanol respectively to remove unreacted products and water respectively. The collected white slurry was oven-dried at 60°C for 24 hrs and the Sc -ZnO NPs were grinded manually to form a fine powder and collected in an airtight glass vial in desiccator until further use. Characterization analysis of Sc -ZnO Nanoparticles Optical characteristics of biogenic Sc -ZnO nanoparticles were obtained UV-spectrophotometer (Multiskan GO; Thermo Scientific) over a range of (800 − 200 nm) wavelength. Through Tauc equation, the direct optical band gap energy was deduced using the equation. \(\:{\left(\varvec{\alpha\:}\mathbf{h}\varvec{\nu\:}\right)}^{1/\mathbf{n}}\:=\:\mathbf{A}\:(\mathbf{h}\varvec{\nu\:}\:-\:\mathbf{E}\mathbf{g})\) ……………… Eq. (1 ) Where; α = absorption coefficient, A is the constant of proportionality, h is the Planck’s constant, ν = frequency of Photons and E g is the Bandgap. Information about the vibrational features from (4000 − 400 cm − 1 ) were collected using FTIR spectrophotometer (Thermo-Fisher, Nicolet 6700). Crystal identity was obtained through fallouts from (XRD), X-ray diffractometer, (Rigaku Ultima IV), and the intensity data was obtained over 2θ range from 20°–80°. The average crystallite size of Sc -ZnO NPs were considered using Scherrer equation: \(\:\varvec{D}=\frac{\mathbf{{\rm\:K}}\varvec{\lambda\:}}{\varvec{\beta\:}\mathbf{C}\mathbf{o}\mathbf{s}\varvec{\theta\:}}\) ……………… Eq. (2 ) Where D represent the crystallite size, K is the Scherrer constant (0.9), λ is the wavelength of x-ray (0.15406 nm), β represent the full width at half maximum (FWHM) of diffraction peak to equivalent crystallographic plane and θ is the angle of the diffracted peak. To reveal the morphology and elemental composition of the synthesized nanoparticles, FE-SEM equipped with EDS detector were used. Furthermore, HR-TEM images at different magnifications were also obtained and average particle size of the crystals was deduced through Image J software. To unravel the stability, zeta potential data was obtained with Malvern zeta-sizer. Antioxidation-DPPH Assay of Sc -ZnO NPs The scavenging of free radicals by Sc -ZnO NPs were measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method as defined by ( Elrefaey et al. 2022 ). In brief, 0.1 mM of DPPH solution in absolute methanol was prepared and allowed to react with two-fold diluted concentrations of sonicated Sc- ZnO NPs (1000 to 3.9) µg/ml. 20µl of each concentration was mixed with 180µl of methanolic-DPPH. The mixtures were incubated in the dark at room temperature for 30 minutes, and absorbance was measured. using a plate reader set at 517 nm. For the control methanolic DPPH solution was used, and for standard plot, ascorbic acid (10–100) µg/ml was used. Antioxidant activity of Sc- ZnO NPs along with the standard was calculated as radical scavenging activity (%RSA) by equation below and IC 50 values were also calculated. \(\:\mathbf{\%}\mathbf{R}\mathbf{S}\mathbf{A}\:=\frac{\left(\mathbf{A}\mathbf{c}\:-\:\mathbf{A}\mathbf{s}\right)}{\left(\mathbf{A}\mathbf{c}\right)}\varvec{*}100\) ………………. Eq. (3 ) Where; A C and A S represent absorbance of control and test sample respectively. Antimicrobial Assay and Determination of MIC: The disc diffusion method was employed to analyse the anti-bacterial potential of Sc -ZnO NPs against four bacterial strains. Overnight bacterial cultures were prepared from the bacterial stocks using 9 ml sterile Soybean-Casein-Digest (SCD) broth medium under Laminar Air Flow (LAF; JSGW, India) and incubated at 37°C. Before use, all the cultures were adjusted to 0.5 McFarland standard or (10 8 C.F.U./ml), A 260 = 0.1 O.D., using standard sterile saline solution on the UV-vis. spectrophotometer. 10 µl of these adjusted microbial cultures were spread individually using a sterile spreader on sterile Muller-Hilton agar (MHA) plates. Next, sterile discs containing the Sc -ZnO NPs (125–250) µg/ml, were transferred to MHA plates. Broad- range antibiotic, Ciprofloxacin served as positive control for all bacterial strains whereas, D.M.S.O. served as negative control. At last, the plates were incubated for 24 hrs at 37°C, and the zone of inhibition was tested for antibacterial potential. Microbroth dilution method was employed to assay the MIC of Sc -ZnO NPs. For this, in a 96-well U-bottom microplate, two-fold dilutions of Sc -ZnO NPs in 5% DMSO were mixed with 100µL nutrient broth. Next, 6µl of bacterial strains (count adjusted to 0.5 x 10 5 CFU) were inoculated separately and incubated for 22 h at 37˚C. The lowermost concentration of Sc -ZnO NPs where no observable growth or pellet at the base of wells of the subjected microbial strain was marked as the MIC value for the respective bacterial strain. The assay was counter analysed by adding 5µl resazurin dye to the respective wells, the microwell plates were further incubated for 3 hrs. The color change in medium from light yellow to purple blue becomes a marker of metabolizing or living cells, while no change in color represents inhibition of the cultured cells by the sample. Photocatalytic Degradation of Congo Red The photocatalytic activity of Sc -ZnO NPs were investigated using organic textile azo dye; Congo red using method described in literature. Briefly, 10mg of the Sc-ZnO NPs was supplemented to 200 ml of dye solution and stirred for 20 min in dark to achieve the adsorption-desorption equilibrium. Next, the experimentation proceeded under sunlight while continuously agitated on the stirrer to evaluate the ability of the catalyst to degrade CR. 3 ml of this solution was extracted at 10 min intervals then centrifuged to isolate the catalyst and the absorption of the leftover CR solution was quantified in UV spectrophotometer. Degradation efficiency of CR was determined using the maximum absorbance peak revealed by CR in presence of sunlight. The degradation percentage of CR and the rate constant of the photocatalyst reaction was assessed using equations 4 and 5. \(\:\mathbf{\%}\:\mathbf{D}\mathbf{e}\mathbf{g}\mathbf{r}\mathbf{a}\mathbf{d}\mathbf{a}\mathbf{t}\mathbf{i}\mathbf{o}\mathbf{n}=\frac{\mathbf{C}0-\mathbf{C}}{\mathbf{C}0}*100\) …………… eq. (4) Rate of reaction (pseudo first order); \(\:\varvec{l}\varvec{n}\frac{\mathbf{C}0}{\mathbf{C}}=\:-\mathbf{k}\mathbf{t}\) …………… eq. (5) where, C and C 0 represents the concentration of dye; (t) is the time in min ln is the natural log and; k is the Rate constant. Statistical Analysis The results are shown as Mean SD as all the observations were recorded in triplicates and the results were presented using GraphPad Prism version 8, along with values of means ± SE. Results and Discussion Optical Properties of Sc -ZnO Nanoparticles UV-Vis. Spectra after 48 h of incubation depicted an absorption maximum at 372 nm, demonstrated the creation of Sc-ZnO NPs. ( Fig. 2 A ). The spectra depict electron oscillations from valence to conduction band when interacted at specific wavelength of light, known as localized surface plasmon resonance (LSPR) and its existence between (310–380) nm is distinctive for ZnO NPs. This peak at 372 nm likewise corresponds to monodispersing feature of Sc-ZnO NPs and similar observations have been reported by ( Amin et al. 2023 ). However, peaks at higher wavelength also describes aggregation, due to shortened bandgap that consequently leads to an increased particle size. UV-Vis. Data was also used to estimate the band gap value (E g ) and was calculated as 3.42 eV, as depicted in inset of Fig. 2 . variation in band gap can be due to a structural parameter and to the size of the grains. A narrowed bandgap is linked with the improvement in crystallinity, due to change in annealing temperature that loads dopant on Zn and O vacancies in ZnO structure. FTIR spectrogram ( Fig. 2 B ) of the fabricated Sc -ZnO NPs were recorded to reveal the participation of functional groups that capped and stabilized the ZnO structure. The peak at 3428 cm − 1 is ascribed to H–O vibration indicative of presence of intramolecular water, peak at 1566 cm − 1 denoted C = O groups chiefly from compounds from phenols that are comprised of highly conjugated rings, ( Khajuria et al. 2025 ); C = C aromatic stretching C = C groups. At the fingerprint region the peak at 1403 cm − 1 C–N of phytochemical chiefly, phenols and flavonoids that bonded to the surface of nanoparticles ( Vera et al. 2023 ). Zn-O stretching is observed between (600–450) cm − 1 indicative of formation of Sc-ZnO NPs from the phytochemicals present in the plant extract that were successfully absorbed onto the surface of during synthesis. Crystallographic Analysis: For the determination of crystalline from of powdered samples, X-ray diffraction is recognized as most valuable and non-destructive analytical system. The structural features of Sc -ZnO NPs are apparent from the pattern reveals sharp diffraction peaks indicative of crystalline nature. Significant diffraction intensities observed at 2 θ values of 31.74, 34.42, 36.27, 47.51, 56.54, 62.81, 67.91, 69.10, 72.57, 76.94 corresponds to the reflections attributed to, Miller indices ( hkl ) of (100), (002), (101), (102), (110), (103), (200), (112), (210), and (004) planes of hexagonal phase ZnO structure. The fallouts were matched in accordance to the JCPDS (01-079-2205) card and are consistent with those of ( Oktapia et al. 2023 ). The calculated average crystallite size using Deby-Scherrer’s equation was 20.94 nm, and the calculated crystallinity percentage of 74.26% was obtained. Morphological analysis Field-emission Surface electron microscopy (FE-SEM) and Transmission electron microscopy (TEM) exposed the morphology and the average particle size of Sc -ZnO NPs were evaluated. FE-SEM revealed clustered flake-like morphology of the particles at 1µm scale ( Fig. 4 -A ) . Through the EDS detector, the scanned field provided the elemental composition of the nanoparticles shown in ( Fig. 4 B-D ) . The calculated weight percentage of Zn and O was 70.09% and 29.91% respectively. Similar irregular and pseudo-spherical morphology were observed through HR-TEM ( Fig. 5 A & B) where the lognormal average particle size of Sc- ZnO NPs was calculated as 31.16 nm using histogram analysis ( Fig. 5 -C ) . Through TEM analysis it was observed that the particle has undergone agglomeration that proves 1ml of plant extract and 0.2 mM of zinc acetate dihydrate allowed optimal background for Sc- ZnO NPs synthesis and the distance between particles were markedly less. Figure 5 -D, displays the SAED pattern that proves the polycrystalline nature of Sc- ZnO NPs. However, the aggregation is Colloidal Stability: The physical stability of nanoparticles suspension can be measured by their surface charge or zeta potential that is generated due to the potential difference between the diffused and fixed layer on the surface. Typically, zeta potential of nanoparticles, the values ranging below − 30 mV and above + 30 mV are considered as stable suspensions and the values between the range have low to moderate stability chiefly due to aggregation of particles and flocculation caused by attractions created by Van der Waals forces ( Singh et al. 2021 ). In our case, the zeta potential was measured as -17 mV with water as dispersant; Fig. 6 . Moderate stability of Sc -ZnO NPs was recorded and the results are in agreement with the HR-TEM and SEM data, where, aggregation is morphologically evident. DPPH Assay of Sc -ZnO NPs The extinction capacity of DPPH free radicals was harboured to forage free ROS species and the scavenging activity was quantified spectrophotometrically for both the control (ascorbic acid) and test-sample ( Sc -ZnO NPs). The fabricated nanoparticles displayed profound antioxidant activity and the percentage against DPPH radicals upsurges linearly with increase in concentration throughout the reaction. Figure 7 ; shows the Percent RSA and IC 50 values for each; standard (ascorbic acid) and Sc -ZnO NPs. The percent RSA was calculated in the range of two-fold dilution starting from 1mg/ml as shown in Fig. 9 that exceeded from the range of standard (10–100) µg/ml. The calculated IC 50 value of ascorbic acid was 40.3 ± 2.3 µg/ml that was nearly half of Sc- ZnO NPs at 74.16 ± 16.91 µg/ml; however, indicative of effective antioxidant. Similar results were obtained by the Zno NPs synthesized from A. altissima leaf extract ( Awan et al. 2023 ). Free radicals are generated in the metabolizing cells at overwhelming amounts leading to a state of oxidative stress. ROS species and O 2 metabolites (derivatives from NADPH oxidase of the electron transport chain) are highly unstable and reactive species that cause membrane damage to the cells and oxidises the DNA, proteins and lipids. ROS also produces RNS (reactive nitrogen species) by reacting with nitric oxide imparting a nitrosative stress condition that escalates production of high levels of free radicals and are responsible for post-translational protein modifications that alters protein functionality ( Kyene et al. 2023 ). Altogether, ROS and RNS are causal agents of numerous aliments such as inflammation, cancer, neuro and cardiovascular degenerative diseases (Awan et al. and Rehman et al. 2023 ) Antioxidant agents such as phytochemicals from plant sources have been proven to counteract against ROS agents. The Oxygen atom from Sc- ZnO NPs; and the phenolic phytochemicals involved in capping and stabilization could have donated electrons and quenched the ROS species ( Rehman et al. 2023 ). Antimicrobial Potential and Determination of MIC Four Gram-negative ( Klebsiella pneumoniae, Proteus vulgaris, Aeromonas hydrophila , and Salmonella typhimurium ) and one Gram-positive bacterial strain ( Bacillus cereus ) were tested to observe the antibacterial potential of biogenic Sc -ZnO NPs. Ciprofloxacin was employed as positive control against all strains of bacteriae. Sc -ZnO NPs showed highest inhibition against K. pneumoniae (18.47 ± 1.36 mm) compared to Ciprofloxacin (22. 27 ± 0.37 mm). S. typhimurium also displayed clear inhibitory effect of (15.27 ± 0.64) equated to Ciprofloxacin (21.87 ± 0.7). Inhibition of P. vulgaris and A. hydrophila were also achieved that are less documented, producing inhibition zones of (13.1 ± 1.01 mm) and (12.2 ± 0.72 mm) respectively. Among the Gram-positive strain, B. cereus , produced significant inhibition zone of (13.27 ± 1.12 mm) compared to ciprofloxacin (20.37 ± 0.58 mm). Overall, Sc- ZnO-NPs demonstrated effectual inhibition against all strains of pathogenic bacteria, as shown in ( Fig. 8 ) . The minimum inhibitory concentration (MIC) of the above tested pathogens was also calculated by micro-broth dilution assay as stated in Table 1 . MIC for K. pneumoniae was and was affected with only 31.25 µg/ml concentration Sc-ZnO NPs, followed by S. typhimurium where 62.5 µg/ml was found to inhibit the growth. At 125 µg/ml, B. cereus , P. vulgaris and A. hydrophila were also inhibited. The inhibitory effect of Sc- ZnO NPs may arise with their attachment to the peptidoglycan layers of the bacterial cells where possible destruction of cell wall may have arisen by brittle morphology of nanoparticles. The small size allows the nanoparticles to penetrate deep inside the cell wall and maximize the overall reactions with the surrounding peptidoglycan subunits, namely N-acetyl muramine (NAM), N-acetyl glucosamine (NAG) and linker chains of amino acids. Gram positive bacterial cells show great resistance to oxidative stress produced by ZnO NPs owing to their thick cell wall. Here, the generation of ROS, (H 2 O 2 ) from the surface NPs have been reported to produce bactericidal response; also, H 2 O 2 production is greatly dependant with the surface area of ZnO NPs ( Kyene et al. 2023 ). The second layer in bacterial cells is the cell wall, that upon contact with ZnO structure could have affected the permeability of the phospholipid bilayer or leakage of intracellular protein, by the release of zinc ions leading to membrane disruption ( Alamdari et al. 2020 ). Abundant presence of hydroxyl and carbonyl groups from the extract could have enhanced the Sc -ZnO NPs to adhere to the cell membrane that triggered the membrane hydroxylation that became toxic to the cells ( Singh et al. 2021 ). Furthermore, ZnO nanoparticles also been reported for cell lysis through inhibition of cell proteins that fuses with the thiol (-SH) groups. Other mechanisms also include inhibition of DNA replication by interacting with the phosphorous groups in the DNA structure, that eventually inhibits the synthesis of proteins ( Elrefaey et al. 2022 ). Hence, incorporating Sc- ZnO NPs for antibacterial therapeutics associated with less health hazards could be a wise option. Table 1 Minimum inhibitory concentration (MIC) of Sc -ZnO NPs against bacterial species. Microorganisms Zone of Inhibition (in mm) ± SD MIC Sc -ZnO NPs Ciprofloxacin (µg/ml) S. typhi (MTCC 3224) 15.27 ± 0.64 21.87 ± 0.7 62.5 B. cereus (MTCC 430) 13.27 ± 1.12 20.37 ± 0.58 125 A. hydrophilla (MTCC 1771) 12.2 ± 0.72 17.23 ± 0.39 125 K. pneumoniae (MTCC 3884) 18.47 ± 1.36 22. 27 ± 0.37 31.25 P. vulgaris (MTCC 106) 13.1 ± 1.01 15.5 ± 0.36 125 Photocatalytic Degradation of Congo Red The degradation of Azo dye Congo red (CR) was conducted in presence of sunlight and the absorbance was measured with UV– vis . Spectrophotometer both, with and without Sc -ZnO nanoparticles. Degradation of CR without Sc -ZnO, exhibited least degradation represented and the degradation absorbance of CR was found less during the first 20 min of the reaction with Sc- ZnO NPs. Nevertheless, with the passage of time, the degradation was prominent as there was clear observation of discoloration of CR and was periodically monitored through the absorbance of the reaction. Figure 9, illustrates the possible mechanism of breakdown of CR when reacted with Sc-ZnO NPs in presence of sunlight. There was no observed shift in the peaks of individual absorbance of CR, however, the peak height condensed displaying reduced absorbance, corelating with the discoloration, was considered to calculate CR degradation ( Fig. 10 ; A-D). We determined 91.20% degradation of CR using Sc -ZnO NPs shown in ( Fig. 10 ; B) . Molecular modifications in the structure of molecules during photocatalysis deviates functionally with the time of degradation ( Hitkari et al. 2022 ). One major peak at 494 nm and one minor peak at 343 nm was observed from the start of the experiment, that corresponded to presence of azo bond of CR, benzene and naphthalene ring respectively ( Fig. 10 ; A) . All three peaks pointedly reduced as the photocatalytic degradation progressed during initial 20 min in sunlight. The cleavage in azo bond was maximally observed in absorption after 60 min. The first order rate constant from the photocatalysis was calculated as -0.0398 min − 1 ( Fig. 10 ; D) . The possible mechanism of photocatalytic degradation of CR can be explained through the stochiometric gain of photon-generated e − to oxygen (Fig. 9) that develops to superoxide anion (O 2 •−), though not that reactive, rather a precursor to highly reactive hydrogen peroxide and hydroxyl radicals, (OH•), enhances the oxidizing activity between the bonds present in CR during the photocatalytic reaction in presence of incident sunlight. The identified pattern of the mass fragment was of ringed-benzene, aromatic ring cleaved-off C-S bonds, disruption of N = N bonds and cleaved-off C-N and C-C bonds from the chromophore ( Fowsiya et. al. 2016 ). Conclusion In this investigation, zinc oxide nanoparticles were biogenically synthesized by the leaf aqueous extract of Solidago canadensis L. which proves that the phytochemicals present in plant extract have significant reducing property to synthesize nanoparticles. UV, FTIR, XRD, HR-TEM, SEM and DLS revealed different characteristics of the fabricated Sc -ZnO NPs. The nanomaterial had significant potential of an operative antioxidant and an antibacterial agent against both Gram-positive and Gram-negative bacterial strains. The minimal inhibitory concentration of the synthesized nanoparticles was determinative about the concentrations to be used in practical applications. The photocatalytic degradation of Congo red using Sc- ZnO NPs was measured spectrophotometrically and signifies the capability to reduce Congo red di-azo dye in an hour time-period. Consequently, the usage of S . canadensis extract capped nanoparticles may find value-added applications in photocatalysis and biomedical research. Declarations Authors Contribution Lokesh Kumar Tripathi , conceptualization, investigation, analysis, writing original draft and editing; Rishendra Kumar ; editing and reviewing. Data Availability Statement: The datasets generated during and/or analysed during the current study are available from the correseponding author on reasonable request. Funding: Not Applicable Ethics Declaration: Not Applicable Consent to Publish declaration : Not Applicable Consent To Participate Declaration: Not Applicable Conflict of Interest The authors proclaim no conflict of financial interest for this study. Acknowledgments We highly acknowledge the help of the Malaviya National Institute of Technology (MNIT), Jaipur, India for SEM- EDX, XRD, HR-TEM and DLS analysis. 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Clean Chem Eng 1:100003. 10.1016/j.clce.2022.100003 Khajuria AK, Kandwal A, Sharma RK, Bachheti RK, Worku LA, Bachheti A (2025) In vitro antioxidant and antibacterial activities of biogenic synthesized zinc oxide nanoparticles using leaf extract of Mallotus philippinensis Mull. Arg. Sci Rep 15(1):6541. https://doi.org/10.1038/s41598-025-85264-z Khan S, Noor T, Iqbal N, Yaqoob L (2024) Photocatalytic dye degradation from textile wastewater: a review. ACS omega 9(20):21751–21767. https://doi.org/10.1021/acsomega.4c00887 Kyene MO, Droepenu EK, Ayertey F, Yeboah GN, Archer MA, Kumadoh D, Appiah AA (2023) Synthesis and characterization of ZnO nanomaterial from Cassia sieberiana and determination of its anti-inflammatory, antioxidant and antimicrobial activities. Sci Afr 19:e01452. https://doi.org/10.1016/j.sciaf.2022.e01452 Mcyotto F, Wei Q, Macharia DK, Huang M, Shen C, Chow CW (2021) Effect of dye structure on color removal efficiency by coagulation. Chem Eng J 405:126674. https://doi.org/10.1016/j.cej.2020.126674 Modi S, Yadav VK, Gacem A, Ali IH, Dave D, Khan SH, Jeon BH (2022) Recent and emerging trends in remediation of methylene blue dye from wastewater by using zinc oxide nanoparticles. Water 14(11):1749. https://doi.org/10.3390/w14111749 National Center for Biotechnology Information (2025) PubChem Compound Summary for CID 11313, Congo Red. Retrieved July 4, 2025 from https://pubchem.ncbi.nlm.nih.gov/compound/Congo-Red Oktapia D, Nurfani E, Wahjoedi BA, Nulhakim L, Kadja GT (2023) Seedless hydrothermal growth of hexagonal prism ZnO for photocatalytic degradation of methylene blue: the effect of pH and post-annealing treatment. Semicond Sci Technol 38(10):105005. 10.1088/1361–6641/acf397 Ostovar N, Mohammadi N, Khodadadeh F (2023) Photocatalytic, antioxidant and antibacterial potential of bio-synthesized ZnO nanoparticles derived from espresso spent coffee grounds: optimization by central composite design. Inorg Nano-Metal Chem 53(9):938–949. https://doi.org/10.1080/24701556.2023.2187419 Pavel M, Anastasescu C, State RN, Vasile A, Papa F, Balint I (2023) Photocatalytic degradation of organic and inorganic pollutants to harmless end products: assessment of practical application potential for water and air cleaning. Catalysts 13(2):380. https://doi.org/10.3390/catal13020380 Rehman H, Ali W, Khan NZ, Aasim M, Khan T, Khan AA (2023) Delphinium uncinatum mediated biosynthesis of zinc oxide nanoparticles and in-vitro evaluation of their antioxidant, cytotoxic, antimicrobial, anti-diabetic, anti-inflammatory, and anti-aging activities. Saudi J Biol Sci 30(1):103485. https://doi.org/10.1016/j.sjbs.2022.103485 Saad Algarni T, Abduh NA, Kahtani A, A., Aouissi A (2022) Photocatalytic degradation of some dyes under solar light irradiation using ZnO nanoparticles synthesized from Rosmarinus officinalis extract. Green Chem Lett Rev 15(2):460–473. https://doi.org/10.1080/17518253.2022.2089059 Siddiqui SI, Allehyani ES, Al-Harbi SA, Hasan Z, Abomuti MA, Rajor HK, Oh S (2023) Investigation of Congo red toxicity towards different living organisms: a review. Processes 11(3):807. https://doi.org/10.3390/pr11030807 Singh TA, Sharma A, Tejwan N, Ghosh N, Das J, Sil PC (2021) A state of the art review on the synthesis, antibacterial, antioxidant, antidiabetic and tissue regeneration activities of zinc oxide nanoparticles. Adv Colloid Interface Sci 295:102495. https://doi.org/10.1016/j.cis.2021.102495 Tara N, Siddiqui SI, Rathi G, Chaudhry SA, Inamuddin, Asiri AM (2020) Nano-engineered adsorbent for the removal of dyes from water: A review. Curr Anal Chem 16(1):14–40. https://doi.org/10.2174/1573411015666190117124344 Tiwari AK, Jha S, Tripathi SK, Shukla R, Awasthi RR, Bhardwaj AK, Dikshit A (2024) Spectroscopic investigations of green synthesized zinc oxide nanoparticles (ZnO NPs): antioxidant and antibacterial activity. Discover Appl Sci 6(8):399. https://doi.org/10.1007/s42452-024-06049-z Vera J, Herrera W, Hermosilla E, Díaz M, Parada J, Seabra AB, Rubilar O (2023) Antioxidant activity as an indicator of the efficiency of plant extract-mediated synthesis of zinc oxide nanoparticles. Antioxidants 12(4):784. https://doi.org/10.3390/antiox12040784 Verma R, Dwivedi GK, Singh JP, Singh AP, Tamta N, Kumar A (2023) Characterization of synthesized zinc oxide nanoparticles and their effect on growth, productivity and zinc use efficiency of wheat and field pea in the Indian Himalayan foothills. Curr Sci 1319–1328. 10.18520/cs/v124/i11/1319-1328 Yakupova EI, Bobyleva LG, Vikhlyantsev IM, Bobylev AG (2019) Congo Red and amyloids: history and relationship. Biosci Rep 39(1):BSR20181415. https://doi.org/10.1042/BSR20181415 Yates E, Yates A (2016) Johann Peter Griess FRS (1829–88): Victorian brewer and synthetic dye chemist. Notes Records: Royal Soc J History Sci 70(1):65–81. https://doi.org/10.1098/rsnr.2015.0020 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7267346","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":509967995,"identity":"4bcc6fc6-3bca-4e60-b4a2-09e8f4b701ad","order_by":0,"name":"Lokesh Kumar Tripathi","email":"data:image/png;base64,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","orcid":"","institution":"Kumaun University","correspondingAuthor":true,"prefix":"","firstName":"Lokesh","middleName":"Kumar","lastName":"Tripathi","suffix":""},{"id":509967996,"identity":"96a58336-ee13-49da-9d55-ae6705f51baa","order_by":1,"name":"Rishendra Kumar","email":"","orcid":"","institution":"Kumaun University","correspondingAuthor":false,"prefix":"","firstName":"Rishendra","middleName":"","lastName":"Kumar","suffix":""}],"badges":[],"createdAt":"2025-08-01 04:53:15","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-7267346/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7267346/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":90998591,"identity":"c5ca3ef7-8a57-46e1-b5f2-8806e5801622","added_by":"auto","created_at":"2025-09-10 13:10:08","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":345150,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic illustration of \u003cem\u003eS. canadensis\u003c/em\u003emediated synthesis of Sc-ZnO NPs\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7267346/v1/9e825f6ec0c86473cd01ba0a.png"},{"id":90998590,"identity":"2fc75a46-7e16-4956-a897-9816fe331046","added_by":"auto","created_at":"2025-09-10 13:10:08","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":567093,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(A) \u003c/strong\u003eUV spectra at (800-200) nm and Tauc Plot in inset; \u003cstrong\u003e(B) \u003c/strong\u003eFTIR\u003cstrong\u003e \u003c/strong\u003eof \u003cem\u003eSc\u003c/em\u003e-ZnO NPs.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7267346/v1/3b2f486ef8b9683e0ad242ff.png"},{"id":90998596,"identity":"8054a50e-d4d8-45f2-82ae-f94563c7d1a8","added_by":"auto","created_at":"2025-09-10 13:10:08","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":156674,"visible":true,"origin":"","legend":"\u003cp\u003eXRD fallouts of Sc-ZnO NPs with respect to JCPDS (01-079-2205)\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7267346/v1/5a0fdfe92beb603e35ff5dd5.jpg"},{"id":90998841,"identity":"aeb08d1b-98f6-4f33-8d41-9cdcc7cb6964","added_by":"auto","created_at":"2025-09-10 13:18:08","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1149148,"visible":true,"origin":"","legend":"\u003cp\u003eFE-SEM image of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs at \u003cstrong\u003e(A) \u003c/strong\u003e1µm scale; \u003cstrong\u003e(B)\u003c/strong\u003e EDS spectrogram;\u003cstrong\u003e (C) \u003c/strong\u003eEDS selection and \u003cstrong\u003e(D)\u003c/strong\u003eTable representing the elemental composition of \u003cem\u003eSc\u003c/em\u003e-ZnO.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7267346/v1/d26eac06babdca653343d4d2.png"},{"id":90998593,"identity":"4922c322-d371-4ac5-8c53-7cfc35303246","added_by":"auto","created_at":"2025-09-10 13:10:08","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":2250476,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(A)\u003c/strong\u003e HR-TEM images of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs at 200 nm \u003cstrong\u003e(B)\u003c/strong\u003e at 100 nm \u003cstrong\u003e(C) \u003c/strong\u003eHistogram of average particle size \u003cstrong\u003e(D)\u003c/strong\u003e SAED pattern of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7267346/v1/ce5440e535488085ec67748c.png"},{"id":90999935,"identity":"83bc86c9-716d-4755-8c3f-d44f3beb996d","added_by":"auto","created_at":"2025-09-10 13:26:08","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":47389,"visible":true,"origin":"","legend":"\u003cp\u003eGraph displaying the measured zeta potential of the fabricated Sc-ZnO NPs.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7267346/v1/176d7031176d99c7932153ba.png"},{"id":90998628,"identity":"0ad07131-11db-4b61-9e5e-57e9da8bcc76","added_by":"auto","created_at":"2025-09-10 13:10:10","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":309345,"visible":true,"origin":"","legend":"\u003cp\u003eGraphs A and B; displaying the %RSA and IC\u003csub\u003e50\u003c/sub\u003e values of means ± SE respectively.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7267346/v1/afdf0cf33066485378552a16.png"},{"id":90998845,"identity":"659c2ea9-095e-424c-a563-276b4d71b3b7","added_by":"auto","created_at":"2025-09-10 13:18:08","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":1019364,"visible":true,"origin":"","legend":"\u003cp\u003eDisc-diffusion assay for antibacterial potential of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs against pathogenic bacterial strains on Muller-Hilton agar plates.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-7267346/v1/ecb2a4e534b8ea629cc4b948.png"},{"id":90998844,"identity":"b030105a-aaf3-444e-b035-5f38039b13e6","added_by":"auto","created_at":"2025-09-10 13:18:08","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":154371,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic Mechanics of photocatalytic degradation of Congo-Red by \u003cem\u003eSc\u003c/em\u003e-ZnO NPs\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-7267346/v1/37165062a9e5d0df3cedbe0d.png"},{"id":90998851,"identity":"80f9bbb1-1cad-46f9-8530-2b2c594fb171","added_by":"auto","created_at":"2025-09-10 13:18:09","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":770201,"visible":true,"origin":"","legend":"\u003cp\u003eCongo-Red photodegradation by \u003cem\u003eSc\u003c/em\u003e-ZnO NPs \u003cstrong\u003e(A)\u003c/strong\u003e Absorbance of degradation; \u003cstrong\u003e(B)\u003c/strong\u003e Photodegradation percentage; \u003cstrong\u003e(C) \u003c/strong\u003eKinetics study for pseudo-first-order reaction; \u003cstrong\u003e(D)\u003c/strong\u003e Slope determination for rate constant (min\u003csup\u003e-1\u003c/sup\u003e).\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-7267346/v1/d436babb155bbb0f49c3d64a.png"},{"id":96808211,"identity":"e8995cbc-f928-4ffb-9b3f-ea6489cc032b","added_by":"auto","created_at":"2025-11-26 09:24:46","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8140615,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7267346/v1/d2977c25-ef35-4ab2-a356-aa069f4629d2.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003ePhotocatalytic remediation of Congo red and Pharmacological properties of \u003cem\u003eSolidago canadensis\u003c/em\u003e L.mediated biogenic synthesis of ZnO Nanoparticles\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAzo dyes have been recognized as a colouring agent and its toxicological adversities \u003cb\u003e(\u003c/b\u003eMcyotto et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Congo-red (CR) is a di-azo water-soluble dye (C\u003csub\u003e32\u003c/sub\u003eH\u003csub\u003e22\u003c/sub\u003eN\u003csub\u003e6\u003c/sub\u003eNa\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e6\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003e) that includes two (-N\u0026thinsp;=\u0026thinsp;N-) groups composed of a sodium salt of benzidinediazo-bis-1-naphthylamine-4-sulfonic acid \u003cb\u003e(\u003c/b\u003eTara et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). With a linear symmetry, a molecule of CR contains a hydrophobic centre comprised of two phenyl rings linked with di-azo bonds \u003cb\u003e(\u003c/b\u003eYates \u0026amp; Yates, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2016\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e With the phenyl rings, two terminally charged naphthalene moieties containing sulfonic and amino groups are attached. Due to the presence of di-azo in the chemical structure, CR imparts a characteristic red colour in basic solution and red in acidic solution and forms an amine component; benzidine; due to cleavage of azo groups \u003cb\u003e(\u003c/b\u003eClavijo \u0026amp; Osma, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2019\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. According to the \u003cb\u003e(NCBI, 2025)\u003c/b\u003e, benzidine is recognized as a potent bladder carcinogen and other studies have implicated to activate accumulation of platelets, thrombocytopenia, and circulated micro-embolism, thus, included in the banned category of azo dyes \u003cb\u003e(\u003c/b\u003eSiddiqui, et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). CR is been utilized in textile-dying, colour-cosmetics, pigments, leather-tanning, food-processing, pharmaceuticals, paper and wood-pulp industries and its all-embracing usage have added to the environmental pollution \u003cb\u003e(\u003c/b\u003eYakupova et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e\u003cp\u003ePrevious publications disclose attempts at physical processes such as adsorption, biodegradation, and a few chemical processes utilizing chlorination and ozonation approaches \u003cb\u003e(\u003c/b\u003eModi et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Since, environmental contamination of CR has a wide range of consequences for natural resources, it is critical to develop new methodology for CR remediation \u003cb\u003e(\u003c/b\u003eHaleem et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). CR have multiple functional groups, rigidly bonded to the substrate that hinders the degradation process. Therefore, an advanced oxidation process (AOP) is utilized to eliminate the soluble dyes that are difficult to treat with conventional techniques \u003cb\u003e(\u003c/b\u003eKhan et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). The photocatalysis AOP, is a potential approach for oxidizing organic contaminants. Photocatalysis, employs UV light and catalysts to accelerate the breakdown of azo dyes \u003cb\u003e(\u003c/b\u003ePavel et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eGreen nanoparticles have been observed to increase in a variety of sectors, including chemical science, environment, biotechnological fields \u003cb\u003e(\u003c/b\u003eDangana et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Zinc oxide nanoparticles, among other nano-sized materials, are utilized as auxiliary source of pollutant deterioration because of their high UV light absorption \u003cb\u003e(\u003c/b\u003eSaad Algarni et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). ZnO has a comparatively eclectic band gap of 3.37eV and 60meV of exciton energy has been employed as an efficient photocatalyst for producing reactive oxygen species (ROS) that decompose several pollutants of organic nature \u003cb\u003e(\u003c/b\u003eAlbiss \u0026amp; Abu-Dalo, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. Conventional methods namely, physical and chemical strategies were employed to synthesize nanoparticles \u003cb\u003e(Amin et. al.;\u003c/b\u003e Verma et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Since hazardous substances utilized in the synthesis of NPs, the limitations of conventional approaches cannot be avoided \u003cb\u003e(\u003c/b\u003eSaad Algarni et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) In contrast, the green synthesis approach has gained tremendous attention past decade for the synthesis of ZnO NPs that overcome the utilization of hazardous chemicals \u003cb\u003e(\u003c/b\u003eTiwari et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eFurthermore, the green synthesis process was created to eliminate any environmentally harmful compounds. The availability of phenolics, flavonoids, and alkaloids, plant extract-mediated nanoparticles have been exploited for a variety of pharmacological and environmental applications \u003cb\u003e(\u003c/b\u003eFowsiya et. al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). These phytochemicals reduce, cap and stabilize during synthesis of metallic oxides, generating surface to volume ratio for dye degradation \u003cb\u003e(\u003c/b\u003eOstovar et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). These NPs also have potential antimicrobial and antioxidation activity due to stringent effect of phytochemicals capped to the surface of NPs \u003cb\u003e(\u003c/b\u003eTiwari et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eWith this regard, this study is aimed towards biogenic zinc oxide synthesis using aqueous infusion of an invasive plant \u003cem\u003eSolidago canadensis\u003c/em\u003e L. This species belongs to the \u003cem\u003eAsteraceae\u003c/em\u003e family and together with other family members has been extensively studied for phytochemicals as well as invasive compounds. We characterized the formed \u003cem\u003eSc\u003c/em\u003e-ZnO NPs and analysed for antimicrobial, antioxidant activity and further the photocatalytic activity and kinetics against Congo-red dye are evaluated.\u003c/p\u003e"},{"header":"Methods and Materials","content":"\u003cp\u003eZinc acetate dihydrate and Congo Red was procured from CDH, India; while, DPPH, Ciprofloxacin, Sterile discs, Nutrient Agar, Muller-Hinton Broth, and, SDB was procured from Hi-Media, India, while microbial cultures were procured from MTCC, IMTECH, Chandigarh.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eCollection of Plant Material\u003c/h2\u003e\u003cp\u003eThe leaves of \u003cem\u003eSolidago canadensis\u003c/em\u003e L. were collected from the slopy grasslands of Bhimtal region, (29.35\u0026deg;N longitude and 79.5667\u0026deg;E latitude), during the flowering season (October to mid-November). \u003cem\u003eS. canadensis\u003c/em\u003e L. is an invasive species and does not belong to the IUCN list of endangered species. For the taxonomic identification, (processed by Dr. S.K. Singh), herbarium voucher was prepared with intact flowers and was accessioned at (BSD Student Herbarium) at the office of the Botanical Survey of India (BSI), Northeren Regional Centre, Dehradun, India, with ID number (BSI/NRC HERB (Ident.)/2022-23/1004), and accension number (1305) was obtained.\u003c/p\u003e\u003cp\u003e\u003cb\u003ePreparation of\u003c/b\u003e \u003cb\u003eS. canadensis\u003c/b\u003e \u003cb\u003eL. Aqueous Extracts (\u003c/b\u003e\u003cb\u003eSc-\u003c/b\u003e\u003cb\u003eaq.ex.)\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe aerial parts were collected and shipped to lab in zip-lock bags. After thoroughly cleaning with distilled water the leaves were shed-dried for a week, then powdered and sieved. 10 grams were assorted with Millipore water in 1:10 ratio respectively and heated at 65\u0026deg;C for 30 min in a heated stirrer. Next, this solution was brought to moderate temperature (25\u0026deg;C) and centrifugated at 3000 g for 5 min to isolate the supernatant containing the dissolved phytochemicals. The filtrate was then filtered using Whatman no.1 and collected for storage until further use at 4\u0026deg;C.\u003c/p\u003e\u003cp\u003e\u003cb\u003ePreparation of\u003c/b\u003e \u003cb\u003eSc\u003c/b\u003e\u003cb\u003e-ZnO Nanoparticles\u003c/b\u003e\u003c/p\u003e\u003cp\u003eFor \u003cem\u003eSc-\u003c/em\u003eaq.ex. mediated biogenic synthesis of ZnO nanoparticles, 50 ml of Zinc acetate dihydrate solution (0.2 mM) was stirred in a magnetic shaker for 30 min. To this salt solution, 1 mL of \u003cem\u003eSc\u003c/em\u003e aq. ex., was added dropwise and allowed to form a homogeneous mixture. This mixture was further stirred for 1 hr followed by the adjustment of pH to approx. 12 using (0.2 M) NaOH, for the reaction to complete, thus, forming a white precipitate. The reaction mixture was further aged in dark for 48 hrs \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. Next, the settled white precipitate was washed thrice with ultrapure water using a centrifuge at 10,000 g for 10 min and finally with absolute ethanol respectively to remove unreacted products and water respectively. The collected white slurry was oven-dried at 60\u0026deg;C for 24 hrs and the \u003cem\u003eSc\u003c/em\u003e-ZnO NPs were grinded manually to form a fine powder and collected in an airtight glass vial in desiccator until further use.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eCharacterization analysis of\u003c/b\u003e \u003cb\u003eSc\u003c/b\u003e\u003cb\u003e-ZnO Nanoparticles\u003c/b\u003e\u003c/p\u003e\u003cp\u003eOptical characteristics of biogenic \u003cem\u003eSc\u003c/em\u003e-ZnO nanoparticles were obtained UV-spectrophotometer (Multiskan GO; Thermo Scientific) over a range of (800\u0026thinsp;\u0026minus;\u0026thinsp;200 nm) wavelength. Through Tauc equation, the direct optical band gap energy was deduced using the equation.\u003c/p\u003e\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\left(\\varvec{\\alpha\\:}\\mathbf{h}\\varvec{\\nu\\:}\\right)}^{1/\\mathbf{n}}\\:=\\:\\mathbf{A}\\:(\\mathbf{h}\\varvec{\\nu\\:}\\:-\\:\\mathbf{E}\\mathbf{g})\\)\u003c/span\u003e\u003c/span\u003e \u003cb\u003e\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u003c/b\u003e \u003cb\u003eEq.\u0026nbsp;(1\u003c/b\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003cp\u003eWhere; α\u0026thinsp;=\u0026thinsp;absorption coefficient, A is the constant of proportionality, h is the Planck\u0026rsquo;s constant, ν\u0026thinsp;=\u0026thinsp;frequency of Photons and E\u003csub\u003eg\u003c/sub\u003e is the Bandgap.\u003c/p\u003e\u003cp\u003eInformation about the vibrational features from (4000\u0026thinsp;\u0026minus;\u0026thinsp;400 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) were collected using FTIR spectrophotometer (Thermo-Fisher, Nicolet 6700). Crystal identity was obtained through fallouts from (XRD), X-ray diffractometer, (Rigaku Ultima IV), and the intensity data was obtained over 2θ range from 20\u0026deg;\u0026ndash;80\u0026deg;. The average crystallite size of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs were considered using Scherrer equation:\u003c/p\u003e\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\varvec{D}=\\frac{\\mathbf{{\\rm\\:K}}\\varvec{\\lambda\\:}}{\\varvec{\\beta\\:}\\mathbf{C}\\mathbf{o}\\mathbf{s}\\varvec{\\theta\\:}}\\)\u003c/span\u003e\u003c/span\u003e \u003cb\u003e\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u003c/b\u003e \u003cb\u003eEq.\u0026nbsp;(2\u003c/b\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003cp\u003eWhere D represent the crystallite size, K is the Scherrer constant (0.9), λ is the wavelength of x-ray (0.15406 nm), β represent the full width at half maximum (FWHM) of diffraction peak to equivalent crystallographic plane and θ is the angle of the diffracted peak.\u003c/p\u003e\u003cp\u003eTo reveal the morphology and elemental composition of the synthesized nanoparticles, FE-SEM equipped with EDS detector were used. Furthermore, HR-TEM images at different magnifications were also obtained and average particle size of the crystals was deduced through Image J software. To unravel the stability, zeta potential data was obtained with Malvern zeta-sizer.\u003c/p\u003e\u003cp\u003e\u003cb\u003eAntioxidation-DPPH Assay of\u003c/b\u003e \u003cb\u003eSc\u003c/b\u003e\u003cb\u003e-ZnO NPs\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe scavenging of free radicals by \u003cem\u003eSc\u003c/em\u003e-ZnO NPs were measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method as defined by \u003cb\u003e(\u003c/b\u003eElrefaey et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). In brief, 0.1 mM of DPPH solution in absolute methanol was prepared and allowed to react with two-fold diluted concentrations of sonicated \u003cem\u003eSc-\u003c/em\u003eZnO NPs (1000 to 3.9) \u0026micro;g/ml. 20\u0026micro;l of each concentration was mixed with 180\u0026micro;l of methanolic-DPPH. The mixtures were incubated in the dark at room temperature for 30 minutes, and absorbance was measured. using a plate reader set at 517 nm. For the control methanolic DPPH solution was used, and for standard plot, ascorbic acid (10\u0026ndash;100) \u0026micro;g/ml was used. Antioxidant activity of \u003cem\u003eSc-\u003c/em\u003eZnO NPs along with the standard was calculated as radical scavenging activity (%RSA) by equation below and IC\u003csub\u003e50\u003c/sub\u003e values were also calculated.\u003c/p\u003e\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\mathbf{\\%}\\mathbf{R}\\mathbf{S}\\mathbf{A}\\:=\\frac{\\left(\\mathbf{A}\\mathbf{c}\\:-\\:\\mathbf{A}\\mathbf{s}\\right)}{\\left(\\mathbf{A}\\mathbf{c}\\right)}\\varvec{*}100\\)\u003c/span\u003e\u003c/span\u003e \u003cb\u003e\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;.\u003c/b\u003e \u003cb\u003eEq.\u0026nbsp;(3\u003c/b\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003cp\u003eWhere; A\u003csub\u003eC\u003c/sub\u003e and A\u003csub\u003eS\u003c/sub\u003e represent absorbance of control and test sample respectively.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eAntimicrobial Assay and Determination of MIC:\u003c/h3\u003e\n\u003cp\u003eThe disc diffusion method was employed to analyse the anti-bacterial potential of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs against four bacterial strains. Overnight bacterial cultures were prepared from the bacterial stocks using 9 ml sterile Soybean-Casein-Digest (SCD) broth medium under Laminar Air Flow (LAF; JSGW, India) and incubated at 37\u0026deg;C. Before use, all the cultures were adjusted to 0.5 McFarland standard or (10\u003csup\u003e8\u003c/sup\u003e C.F.U./ml), A\u003csub\u003e260\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.1 O.D., using standard sterile saline solution on the UV-vis. spectrophotometer. 10 \u0026micro;l of these adjusted microbial cultures were spread individually using a sterile spreader on sterile Muller-Hilton agar (MHA) plates. Next, sterile discs containing the \u003cem\u003eSc\u003c/em\u003e-ZnO NPs (125\u0026ndash;250) \u0026micro;g/ml, were transferred to MHA plates. Broad- range antibiotic, Ciprofloxacin served as positive control for all bacterial strains whereas, D.M.S.O. served as negative control. At last, the plates were incubated for 24 hrs at 37\u0026deg;C, and the zone of inhibition was tested for antibacterial potential.\u003c/p\u003e\u003cp\u003eMicrobroth dilution method was employed to assay the MIC of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs. For this, in a 96-well U-bottom microplate, two-fold dilutions of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs in 5% DMSO were mixed with 100\u0026micro;L nutrient broth. Next, 6\u0026micro;l of bacterial strains (count adjusted to 0.5 x 10\u003csup\u003e5\u003c/sup\u003e CFU) were inoculated separately and incubated for 22 h at 37˚C. The lowermost concentration of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs where no observable growth or pellet at the base of wells of the subjected microbial strain was marked as the MIC value for the respective bacterial strain. The assay was counter analysed by adding 5\u0026micro;l resazurin dye to the respective wells, the microwell plates were further incubated for 3 hrs. The color change in medium from light yellow to purple blue becomes a marker of metabolizing or living cells, while no change in color represents inhibition of the cultured cells by the sample.\u003c/p\u003e\n\u003ch3\u003ePhotocatalytic Degradation of Congo Red\u003c/h3\u003e\n\u003cp\u003eThe photocatalytic activity of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs were investigated using organic textile azo dye; Congo red using method described in literature. Briefly, 10mg of the Sc-ZnO NPs was supplemented to 200 ml of dye solution and stirred for 20 min in dark to achieve the adsorption-desorption equilibrium. Next, the experimentation proceeded under sunlight while continuously agitated on the stirrer to evaluate the ability of the catalyst to degrade CR. 3 ml of this solution was extracted at 10 min intervals then centrifuged to isolate the catalyst and the absorption of the leftover CR solution was quantified in UV spectrophotometer. Degradation efficiency of CR was determined using the maximum absorbance peak revealed by CR in presence of sunlight. The degradation percentage of CR and the rate constant of the photocatalyst reaction was assessed using equations 4 and 5.\u003c/p\u003e\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\mathbf{\\%}\\:\\mathbf{D}\\mathbf{e}\\mathbf{g}\\mathbf{r}\\mathbf{a}\\mathbf{d}\\mathbf{a}\\mathbf{t}\\mathbf{i}\\mathbf{o}\\mathbf{n}=\\frac{\\mathbf{C}0-\\mathbf{C}}{\\mathbf{C}0}*100\\)\u003c/span\u003e\u003c/span\u003e \u003cb\u003e\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u003c/b\u003e\u003cb\u003eeq.\u003c/b\u003e\u0026nbsp;\u003cb\u003e(4)\u003c/b\u003e\u003c/p\u003e\u003cp\u003eRate of reaction (pseudo first order);\u003c/p\u003e\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\varvec{l}\\varvec{n}\\frac{\\mathbf{C}0}{\\mathbf{C}}=\\:-\\mathbf{k}\\mathbf{t}\\)\u003c/span\u003e\u003c/span\u003e \u003cb\u003e\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u003c/b\u003e\u003cb\u003eeq.\u003c/b\u003e\u0026nbsp;\u003cb\u003e(5)\u003c/b\u003e\u003c/p\u003e\u003cp\u003ewhere, C and C\u003csub\u003e0\u003c/sub\u003e represents the concentration of dye; (t) is the time in min ln is the natural log and; k is the Rate constant.\u003c/p\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\u003cp\u003eThe results are shown as Mean SD as all the observations were recorded in triplicates and the results were presented using GraphPad Prism version 8, along with values of means\u0026thinsp;\u0026plusmn;\u0026thinsp;SE.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003e\u003cb\u003eOptical Properties of\u003c/b\u003e \u003cb\u003eSc\u003c/b\u003e\u003cb\u003e-ZnO Nanoparticles\u003c/b\u003e\u003c/p\u003e\u003cp\u003eUV-Vis. Spectra after 48 h of incubation depicted an absorption maximum at 372 nm, demonstrated the creation of Sc-ZnO NPs. \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA\u003cb\u003e).\u003c/b\u003e The spectra depict electron oscillations from valence to conduction band when interacted at specific wavelength of light, known as localized surface plasmon resonance (LSPR) and its existence between (310\u0026ndash;380) nm is distinctive for ZnO NPs. This peak at 372 nm likewise corresponds to monodispersing feature of Sc-ZnO NPs and similar observations have been reported by \u003cb\u003e(\u003c/b\u003eAmin et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). However, peaks at higher wavelength also describes aggregation, due to shortened bandgap that consequently leads to an increased particle size. UV-Vis. Data was also used to estimate the band gap value (E\u003csub\u003eg\u003c/sub\u003e) and was calculated as 3.42 eV, as depicted in inset of Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. variation in band gap can be due to a structural parameter and to the size of the grains. A narrowed bandgap is linked with the improvement in crystallinity, due to change in annealing temperature that loads dopant on Zn and O vacancies in ZnO structure.\u003c/p\u003e\u003cp\u003eFTIR spectrogram \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB\u003cb\u003e)\u003c/b\u003e of the fabricated \u003cem\u003eSc\u003c/em\u003e-ZnO NPs were recorded to reveal the participation of functional groups that capped and stabilized the ZnO structure. The peak at 3428 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is ascribed to H\u0026ndash;O vibration indicative of presence of intramolecular water, peak at 1566 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e denoted C\u0026thinsp;=\u0026thinsp;O groups chiefly from compounds from phenols that are comprised of highly conjugated rings, \u003cb\u003e(\u003c/b\u003eKhajuria et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2025\u003c/span\u003e); C\u0026thinsp;=\u0026thinsp;C aromatic stretching C\u0026thinsp;=\u0026thinsp;C groups. At the fingerprint region the peak at 1403 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e C\u0026ndash;N of phytochemical chiefly, phenols and flavonoids that bonded to the surface of nanoparticles \u003cb\u003e(\u003c/b\u003eVera et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Zn-O stretching is observed between (600\u0026ndash;450) cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e indicative of formation of Sc-ZnO NPs from the phytochemicals present in the plant extract that were successfully absorbed onto the surface of during synthesis.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eCrystallographic Analysis:\u003c/h2\u003e\u003cp\u003eFor the determination of crystalline from of powdered samples, X-ray diffraction is recognized as most valuable and non-destructive analytical system. The structural features of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs are apparent from the pattern reveals sharp diffraction peaks indicative of crystalline nature. Significant diffraction intensities observed at 2\u003cem\u003eθ\u003c/em\u003e values of 31.74, 34.42, 36.27, 47.51, 56.54, 62.81, 67.91, 69.10, 72.57, 76.94 corresponds to the reflections attributed to, Miller indices (\u003cem\u003ehkl\u003c/em\u003e) of (100), (002), (101), (102), (110), (103), (200), (112), (210), and (004) planes of hexagonal phase ZnO structure. The fallouts were matched in accordance to the JCPDS (01-079-2205) card and are consistent with those of \u003cb\u003e(\u003c/b\u003eOktapia et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The calculated average crystallite size using Deby-Scherrer\u0026rsquo;s equation was 20.94 nm, and the calculated crystallinity percentage of 74.26% was obtained.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eMorphological analysis\u003c/h3\u003e\n\u003cp\u003eField-emission Surface electron microscopy (FE-SEM) and Transmission electron microscopy (TEM) exposed the morphology and the average particle size of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs were evaluated. FE-SEM revealed clustered flake-like morphology of the particles at 1\u0026micro;m scale \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e-A\u003cb\u003e)\u003c/b\u003e. Through the EDS detector, the scanned field provided the elemental composition of the nanoparticles shown in \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB-D\u003cb\u003e)\u003c/b\u003e. The calculated weight percentage of Zn and O was 70.09% and 29.91% respectively. Similar irregular and pseudo-spherical morphology were observed through HR-TEM \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA \u003cb\u003e\u0026amp; B)\u003c/b\u003e where the lognormal average particle size of \u003cem\u003eSc-\u003c/em\u003eZnO NPs was calculated as 31.16 nm using histogram analysis \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e-C\u003cb\u003e)\u003c/b\u003e. Through TEM analysis it was observed that the particle has undergone agglomeration that proves 1ml of plant extract and 0.2 mM of zinc acetate dihydrate allowed optimal background for \u003cem\u003eSc-\u003c/em\u003eZnO NPs synthesis and the distance between particles were markedly less. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e-D, displays the SAED pattern that proves the polycrystalline nature of \u003cem\u003eSc-\u003c/em\u003eZnO NPs. However, the aggregation is\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\n\u003ch3\u003eColloidal Stability:\u003c/h3\u003e\n\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe physical stability of nanoparticles suspension can be measured by their surface charge or zeta potential that is generated due to the potential difference between the diffused and fixed layer on the surface. Typically, zeta potential of nanoparticles, the values ranging below \u0026minus;\u0026thinsp;30 mV and above +\u0026thinsp;30 mV are considered as stable suspensions and the values between the range have low to moderate stability chiefly due to aggregation of particles and flocculation caused by attractions created by Van der Waals forces \u003cb\u003e(\u003c/b\u003eSingh et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). In our case, the zeta potential was measured as -17 mV with water as dispersant; \u003cb\u003eFig.\u0026nbsp;6\u003c/b\u003e. Moderate stability of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs was recorded and the results are in agreement with the HR-TEM and SEM data, where, aggregation is morphologically evident.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eDPPH Assay of\u003c/b\u003e \u003cb\u003eSc\u003c/b\u003e\u003cb\u003e-ZnO NPs\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe extinction capacity of DPPH free radicals was harboured to forage free ROS species and the scavenging activity was quantified spectrophotometrically for both the control (ascorbic acid) and test-sample (\u003cem\u003eSc\u003c/em\u003e-ZnO NPs). The fabricated nanoparticles displayed profound antioxidant activity and the percentage against DPPH radicals upsurges linearly with increase in concentration throughout the reaction. Figure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003e; shows the Percent RSA and IC\u003csub\u003e50\u003c/sub\u003e values for each; standard (ascorbic acid) and \u003cem\u003eSc\u003c/em\u003e-ZnO NPs. The percent RSA was calculated in the range of two-fold dilution starting from 1mg/ml as shown in Fig.\u0026nbsp;9 that exceeded from the range of standard (10\u0026ndash;100) \u0026micro;g/ml. The calculated IC\u003csub\u003e50\u003c/sub\u003e value of ascorbic acid was 40.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3 \u0026micro;g/ml that was nearly half of \u003cem\u003eSc-\u003c/em\u003eZnO NPs at 74.16\u0026thinsp;\u0026plusmn;\u0026thinsp;16.91 \u0026micro;g/ml; however, indicative of effective antioxidant. Similar results were obtained by the Zno NPs synthesized from \u003cem\u003eA. altissima\u003c/em\u003e leaf extract \u003cb\u003e(\u003c/b\u003eAwan et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Free radicals are generated in the metabolizing cells at overwhelming amounts leading to a state of oxidative stress. ROS species and O\u003csub\u003e2\u003c/sub\u003e metabolites (derivatives from NADPH oxidase of the electron transport chain) are highly unstable and reactive species that cause membrane damage to the cells and oxidises the DNA, proteins and lipids. ROS also produces RNS (reactive nitrogen species) by reacting with nitric oxide imparting a nitrosative stress condition that escalates production of high levels of free radicals and are responsible for post-translational protein modifications that alters protein functionality \u003cb\u003e(\u003c/b\u003eKyene et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Altogether, ROS and RNS are causal agents of numerous aliments such as inflammation, cancer, neuro and cardiovascular degenerative diseases \u003cb\u003e(Awan et al. and\u003c/b\u003e Rehman et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) Antioxidant agents such as phytochemicals from plant sources have been proven to counteract against ROS agents. The Oxygen atom from \u003cem\u003eSc-\u003c/em\u003eZnO NPs; and the phenolic phytochemicals involved in capping and stabilization could have donated electrons and quenched the ROS species \u003cb\u003e(\u003c/b\u003eRehman et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eAntimicrobial Potential and Determination of MIC\u003c/h2\u003e\u003cp\u003eFour Gram-negative (\u003cem\u003eKlebsiella pneumoniae, Proteus vulgaris, Aeromonas hydrophila\u003c/em\u003e, and \u003cem\u003eSalmonella typhimurium\u003c/em\u003e) and one Gram-positive bacterial strain (\u003cem\u003eBacillus cereus\u003c/em\u003e) were tested to observe the antibacterial potential of biogenic \u003cem\u003eSc\u003c/em\u003e-ZnO NPs. Ciprofloxacin was employed as positive control against all strains of bacteriae. \u003cem\u003eSc\u003c/em\u003e-ZnO NPs showed highest inhibition against \u003cem\u003eK. pneumoniae\u003c/em\u003e (18.47\u0026thinsp;\u0026plusmn;\u0026thinsp;1.36 mm) compared to Ciprofloxacin (22. 27\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37 mm). \u003cem\u003eS. typhimurium\u003c/em\u003e also displayed clear inhibitory effect of (15.27\u0026thinsp;\u0026plusmn;\u0026thinsp;0.64) equated to Ciprofloxacin (21.87\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7). Inhibition of \u003cem\u003eP. vulgaris\u003c/em\u003e and \u003cem\u003eA. hydrophila\u003c/em\u003e were also achieved that are less documented, producing inhibition zones of (13.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.01 mm) and (12.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.72 mm) respectively. Among the Gram-positive strain, \u003cem\u003eB. cereus\u003c/em\u003e, produced significant inhibition zone of (13.27\u0026thinsp;\u0026plusmn;\u0026thinsp;1.12 mm) compared to ciprofloxacin (20.37\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58 mm). Overall, \u003cem\u003eSc-\u003c/em\u003eZnO-NPs demonstrated effectual inhibition against all strains of pathogenic bacteria, as shown in \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e8\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. The minimum inhibitory concentration (MIC) of the above tested pathogens was also calculated by micro-broth dilution assay as stated in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. MIC for \u003cem\u003eK. pneumoniae\u003c/em\u003e was and was affected with only 31.25 \u0026micro;g/ml concentration Sc-ZnO NPs, followed by \u003cem\u003eS. typhimurium\u003c/em\u003e where 62.5 \u0026micro;g/ml was found to inhibit the growth. At 125 \u0026micro;g/ml, \u003cem\u003eB. cereus\u003c/em\u003e, \u003cem\u003eP. vulgaris\u003c/em\u003e and \u003cem\u003eA. hydrophila\u003c/em\u003e were also inhibited. The inhibitory effect of \u003cem\u003eSc-\u003c/em\u003eZnO NPs may arise with their attachment to the peptidoglycan layers of the bacterial cells where possible destruction of cell wall may have arisen by brittle morphology of nanoparticles. The small size allows the nanoparticles to penetrate deep inside the cell wall and maximize the overall reactions with the surrounding peptidoglycan subunits, namely N-acetyl muramine (NAM), N-acetyl glucosamine (NAG) and linker chains of amino acids. Gram positive bacterial cells show great resistance to oxidative stress produced by ZnO NPs owing to their thick cell wall. Here, the generation of ROS, (H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e) from the surface NPs have been reported to produce bactericidal response; also, H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e production is greatly dependant with the surface area of ZnO NPs \u003cb\u003e(\u003c/b\u003eKyene et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The second layer in bacterial cells is the cell wall, that upon contact with ZnO structure could have affected the permeability of the phospholipid bilayer or leakage of intracellular protein, by the release of zinc ions leading to membrane disruption \u003cb\u003e(\u003c/b\u003eAlamdari et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Abundant presence of hydroxyl and carbonyl groups from the extract could have enhanced the \u003cem\u003eSc\u003c/em\u003e-ZnO NPs to adhere to the cell membrane that triggered the membrane hydroxylation that became toxic to the cells \u003cb\u003e(\u003c/b\u003eSingh et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Furthermore, ZnO nanoparticles also been reported for cell lysis through inhibition of cell proteins that fuses with the thiol (-SH) groups. Other mechanisms also include inhibition of DNA replication by interacting with the phosphorous groups in the DNA structure, that eventually inhibits the synthesis of proteins \u003cb\u003e(\u003c/b\u003eElrefaey et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Hence, incorporating \u003cem\u003eSc-\u003c/em\u003eZnO NPs for antibacterial therapeutics associated with less health hazards could be a wise option.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMinimum inhibitory concentration (MIC) of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs against bacterial species.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMicroorganisms\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eZone of Inhibition (in mm)\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMIC\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eSc\u003c/b\u003e\u003cb\u003e-ZnO NPs\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eCiprofloxacin\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e(\u0026micro;g/ml)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eS. typhi\u003c/em\u003e (MTCC 3224)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e15.27\u0026thinsp;\u0026plusmn;\u0026thinsp;0.64\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003e21.87\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e62.5\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eB. cereus\u003c/em\u003e (MTCC 430)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e13.27\u0026thinsp;\u0026plusmn;\u0026thinsp;1.12\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003e20.37\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e125\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eA. hydrophilla\u003c/em\u003e (MTCC 1771)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e12.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.72\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003e17.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.39\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e125\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eK. pneumoniae\u003c/em\u003e (MTCC 3884)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e18.47\u0026thinsp;\u0026plusmn;\u0026thinsp;1.36\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003e22. 27\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e31.25\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eP. vulgaris\u003c/em\u003e (MTCC 106)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e13.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.01\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003e15.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e125\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003ePhotocatalytic Degradation of Congo Red\u003c/h2\u003e\u003cp\u003eThe degradation of Azo dye Congo red (CR) was conducted in presence of sunlight and the absorbance was measured with UV\u0026ndash;\u003cem\u003evis\u003c/em\u003e. Spectrophotometer both, with and without \u003cem\u003eSc\u003c/em\u003e-ZnO nanoparticles. Degradation of CR without \u003cem\u003eSc\u003c/em\u003e-ZnO, exhibited least degradation represented and the degradation absorbance of CR was found less during the first 20 min of the reaction with \u003cem\u003eSc-\u003c/em\u003eZnO NPs. Nevertheless, with the passage of time, the degradation was prominent as there was clear observation of discoloration of CR and was periodically monitored through the absorbance of the reaction. Figure\u0026nbsp;9, illustrates the possible mechanism of breakdown of CR when reacted with Sc-ZnO NPs in presence of sunlight. There was no observed shift in the peaks of individual absorbance of CR, however, the peak height condensed displaying reduced absorbance, corelating with the discoloration, was considered to calculate CR degradation \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e10\u003c/span\u003e; \u003cb\u003eA-D).\u003c/b\u003e We determined 91.20% degradation of CR using \u003cem\u003eSc\u003c/em\u003e-ZnO NPs shown in \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e10\u003c/span\u003e; \u003cb\u003eB)\u003c/b\u003e. Molecular modifications in the structure of molecules during photocatalysis deviates functionally with the time of degradation \u003cb\u003e(\u003c/b\u003eHitkari et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). One major peak at 494 nm and one minor peak at 343 nm was observed from the start of the experiment, that corresponded to presence of azo bond of CR, benzene and naphthalene ring respectively \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e10\u003c/span\u003e; \u003cb\u003eA)\u003c/b\u003e. All three peaks pointedly reduced as the photocatalytic degradation progressed during initial 20 min in sunlight. The cleavage in azo bond was maximally observed in absorption after 60 min. The first order rate constant from the photocatalysis was calculated as -0.0398 min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e10\u003c/span\u003e; \u003cb\u003eD)\u003c/b\u003e. The possible mechanism of photocatalytic degradation of CR can be explained through the stochiometric gain of photon-generated e\u003csup\u003e\u0026minus;\u003c/sup\u003e to oxygen \u003cb\u003e(Fig.\u0026nbsp;9)\u003c/b\u003e that develops to superoxide anion (O\u003csub\u003e2\u003c/sub\u003e\u0026bull;\u0026minus;), though not that reactive, rather a precursor to highly reactive hydrogen peroxide and hydroxyl radicals, (OH\u0026bull;), enhances the oxidizing activity between the bonds present in CR during the photocatalytic reaction in presence of incident sunlight. The identified pattern of the mass fragment was of ringed-benzene, aromatic ring cleaved-off C-S bonds, disruption of N\u0026thinsp;=\u0026thinsp;N bonds and cleaved-off C-N and C-C bonds from the chromophore \u003cb\u003e(\u003c/b\u003eFowsiya et. al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn this investigation, zinc oxide nanoparticles were biogenically synthesized by the leaf aqueous extract of \u003cem\u003eSolidago canadensis\u003c/em\u003e L. which proves that the phytochemicals present in plant extract have significant reducing property to synthesize nanoparticles. UV, FTIR, XRD, HR-TEM, SEM and DLS revealed different characteristics of the fabricated \u003cem\u003eSc\u003c/em\u003e-ZnO NPs. The nanomaterial had significant potential of an operative antioxidant and an antibacterial agent against both Gram-positive and Gram-negative bacterial strains. The minimal inhibitory concentration of the synthesized nanoparticles was determinative about the concentrations to be used in practical applications. The photocatalytic degradation of Congo red using \u003cem\u003eSc-\u003c/em\u003eZnO NPs was measured spectrophotometrically and signifies the capability to reduce Congo red di-azo dye in an hour time-period. Consequently, the usage of \u003cem\u003eS\u003c/em\u003e. \u003cem\u003ecanadensis\u003c/em\u003e extract capped nanoparticles may find value-added applications in photocatalysis and biomedical research.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthors Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLokesh Kumar Tripathi\u003c/strong\u003e, conceptualization, investigation, analysis, writing original draft and editing; \u003cstrong\u003eRishendra Kumar\u003c/strong\u003e; editing and reviewing.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement:\u0026nbsp;\u003c/strong\u003eThe datasets generated during and/or analysed during the current study are available from the correseponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003eNot Applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Declaration:\u0026nbsp;\u003c/strong\u003eNot Applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Publish declaration\u003c/strong\u003e:\u0026nbsp;Not Applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent To Participate Declaration:\u0026nbsp;\u003c/strong\u003eNot Applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors proclaim no conflict of financial interest for this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe highly acknowledge the help of the Malaviya National Institute of Technology (MNIT), Jaipur, India for SEM- EDX, XRD, HR-TEM and DLS analysis.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAlamdari S, Sasani Ghamsari M, Lee C, Han W, Park HH, Tafreshi MJ, Ara MHM (2020) Preparation and characterization of zinc oxide nanoparticles using leaf extract of Sambucus ebulus. 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Notes Records: Royal Soc J History Sci 70(1):65\u0026ndash;81. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1098/rsnr.2015.0020\u003c/span\u003e\u003cspan address=\"10.1098/rsnr.2015.0020\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Photocatalysis, Antibacterial, Antioxidation, MIC, XRD, HR-TEM, FTIR, SEM-EDS","lastPublishedDoi":"10.21203/rs.3.rs-7267346/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7267346/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn this study, biogenically mediated \u003cem\u003eSc\u003c/em\u003e-ZnO nano-sized particles were produced via leaf extract of \u003cem\u003eS. canadensis\u003c/em\u003e L. of the \u003cem\u003eAsteraceae\u003c/em\u003e Family and characterized through sophisticated techniques. Optical analysis through UV-\u003cem\u003evis\u003c/em\u003e. spectroscopy revealed formation of \u003cem\u003eSc\u003c/em\u003e-ZnO NPs with peak at 372 nm with calculated bandgap of 3.42 eV. Further, FTIR produced clear signals of participation of phytochemicals. Morphologically, aggregated flaky-structures and elemental composition was revealed through FESEM\u0026thinsp;+\u0026thinsp;EDS and the average size was deduced by TEM. XRD fallouts determined crystal structure of zinc oxide and the average crystallite size of 20.94 nm was deduced. The antibacterial potential and MIC against bacterial pathogens were analysed employing disc-diffusion method and micro-broth dilution assay respectively. Antioxidant potential and IC\u003csub\u003e50\u003c/sub\u003e of the fabricated ZnO was analysed using DPPH assay. Furthermore, the application of fabricated nanoparticles was studied for the photocatalytic degradation of Congo-red. We observed 91.2% degradation efficiency with a first-order rate of reaction of -k = -0.0398. The fabricated Sc-ZnO nanoparticles proved effective degradation of hazardous textile effluents with potential antibacterial nature.\u003c/p\u003e","manuscriptTitle":"Photocatalytic remediation of Congo red and Pharmacological properties of Solidago canadensis L.mediated biogenic synthesis of ZnO Nanoparticles","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-10 13:10:03","doi":"10.21203/rs.3.rs-7267346/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e56ebb31-37e6-4bc6-90ad-01acb4ee13cf","owner":[],"postedDate":"September 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-26T09:24:18+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-10 13:10:03","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7267346","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7267346","identity":"rs-7267346","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}