Ficin-Functionalized Gold Nanoparticles for Selective UV-Vis Colorimetric Detection of Hg²⁺, Cu²⁺, and Cr⁶⁺: Optimization and RGB Image-Based Quantification

Ficin-Functionalized Gold Nanoparticles for Selective UV-Vis Colorimetric Detection of Hg²⁺, Cu²⁺, and Cr⁶⁺: Optimization and RGB Image-Based Quantification | 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 Ficin-Functionalized Gold Nanoparticles for Selective UV-Vis Colorimetric Detection of Hg²⁺, Cu²⁺, and Cr⁶⁺: Optimization and RGB Image-Based Quantification Asraf Alif Rashidi, Mohd Izuan Effendi Halmi, Mohd Rizal Arifin, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8904810/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 28 Apr, 2026 Read the published version in Chemical Papers → Version 1 posted 9 You are reading this latest preprint version Abstract Nowadays heavy metal pollution poses a critical environmental and public health challenge, making affordable detection methods for water quality monitoring urgently needed. To address this issue, we have developed a novel colorimetric detection system based on ficin-functionalized gold nanoparticles (F-AuNPs) evaluated through UV-Vis spectrophotometry and smartphone-based RGB image analysis for the detection of Hg²⁺, Cu²⁺, and Cr⁶⁺. Response Surface Methodology using Box-Behnken Design optimized the functionalization conditions of Ficin to AuNPs (0.2 mM AuNPs conc, 0.01 mM ficin conc, 72 h incubation at 14°C), resulting in an excellent model fit (R² = 0.9818, adequate precision = 26.992). The optimized F-AuNPs exhibited selective aggregation with Hg²⁺, Cu²⁺, and Cr⁶⁺ causing a visible color transition from red to blue gray but remained dispersed in the presence of nine other tested metal ions. Smartphone RGB image analysis yielded excellent linearity (R²≥0.90) with limits of detection (LOD) and limits of quantitation (LOQ) of 0.02 ppm and 0.06 ppm for Hg²⁺, 0.05 ppm and 0.17 ppm for Cu²⁺ and 0.10 ppm and 0.33 ppm for Cr⁶⁺ respectively. This indicates that the sensitivity of Smartphone RGB image is comparable to conventional UV-Vis spectrophotometry at wavelengths A626/A524. Real water samples testing confirmed F-AuNPs feasibility, with spiked samples validating the method's applicability for environmental monitoring. Thus, F-AuNPs colorimetric platform provides a low-cost operation-minimal sample preparation that functions as practical field-ready tool for future near real time monitoring of these heavy metals. Ficin Gold-nanoparticle Heavy metals Colorimetric Optimization UV-Vis spectrophotometry Digital Image Analysis Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 28 Apr, 2026 Read the published version in Chemical Papers → Version 1 posted Editorial decision: Revision requested 02 Mar, 2026 Reviews received at journal 01 Mar, 2026 Reviews received at journal 28 Feb, 2026 Reviewers agreed at journal 22 Feb, 2026 Reviewers agreed at journal 21 Feb, 2026 Reviewers invited by journal 20 Feb, 2026 Editor assigned by journal 18 Feb, 2026 Submission checks completed at journal 18 Feb, 2026 First submitted to journal 17 Feb, 2026 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-8904810","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":595130260,"identity":"0a2d7020-bcad-4fbd-ad66-598f75454a17","order_by":0,"name":"Asraf Alif Rashidi","email":"","orcid":"","institution":"University Putra Malaysia","correspondingAuthor":false,"prefix":"","firstName":"Asraf","middleName":"Alif","lastName":"Rashidi","suffix":""},{"id":595130261,"identity":"fde4aaf1-a5a2-48f2-837d-91979e7db2e0","order_by":1,"name":"Mohd Izuan Effendi 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To address this issue, we have developed a novel colorimetric detection system based on ficin-functionalized gold nanoparticles (F-AuNPs) evaluated through UV-Vis spectrophotometry and smartphone-based RGB image analysis for the detection of Hg\u0026sup2;⁺, Cu\u0026sup2;⁺, and Cr⁶⁺. Response Surface Methodology using Box-Behnken Design optimized the functionalization conditions of Ficin to AuNPs (0.2 mM AuNPs conc, 0.01 mM ficin conc, 72 h incubation at 14\u0026deg;C), resulting in an excellent model fit (R\u0026sup2; = 0.9818, adequate precision\u0026thinsp;=\u0026thinsp;26.992). The optimized F-AuNPs exhibited selective aggregation with Hg\u0026sup2;⁺, Cu\u0026sup2;⁺, and Cr⁶⁺ causing a visible color transition from red to blue gray but remained dispersed in the presence of nine other tested metal ions. Smartphone RGB image analysis yielded excellent linearity (R\u0026sup2;\u0026ge;0.90) with limits of detection (LOD) and limits of quantitation (LOQ) of 0.02 ppm and 0.06 ppm for Hg\u0026sup2;⁺, 0.05 ppm and 0.17 ppm for Cu\u0026sup2;⁺ and 0.10 ppm and 0.33 ppm for Cr⁶⁺ respectively. This indicates that the sensitivity of Smartphone RGB image is comparable to conventional UV-Vis spectrophotometry at wavelengths A626/A524. Real water samples testing confirmed F-AuNPs feasibility, with spiked samples validating the method's applicability for environmental monitoring. Thus, F-AuNPs colorimetric platform provides a low-cost operation-minimal sample preparation that functions as practical field-ready tool for future near real time monitoring of these heavy metals.\u003c/p\u003e","manuscriptTitle":"Ficin-Functionalized Gold Nanoparticles for Selective UV-Vis Colorimetric Detection of Hg²⁺, Cu²⁺, and Cr⁶⁺: Optimization and RGB Image-Based Quantification","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-24 10:30:31","doi":"10.21203/rs.3.rs-8904810/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-02T05:00:54+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-01T09:32:58+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-28T15:18:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"82448101623606075116420401743414026528","date":"2026-02-22T13:06:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"114073599749602472600137693912350468143","date":"2026-02-21T11:04:42+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-20T12:04:46+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-18T18:52:11+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-18T15:23:38+00:00","index":"","fulltext":""},{"type":"submitted","content":"Chemical Papers","date":"2026-02-18T00:10:58+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"chemical-papers","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"chpa","sideBox":"Learn more about [Chemical Papers](http://link.springer.com/journal/11696)","snPcode":"11696","submissionUrl":"https://www.editorialmanager.com/CHPA/default.aspx","title":"Chemical Papers","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"ecec3479-ab23-4a4c-9858-5585c6bde982","owner":[],"postedDate":"February 24th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-05-04T16:01:42+00:00","versionOfRecord":{"articleIdentity":"rs-8904810","link":"https://doi.org/10.1007/s11696-026-04886-3","journal":{"identity":"chemical-papers","isVorOnly":false,"title":"Chemical Papers"},"publishedOn":"2026-04-28 15:57:49","publishedOnDateReadable":"April 28th, 2026"},"versionCreatedAt":"2026-02-24 10:30:31","video":"","vorDoi":"10.1007/s11696-026-04886-3","vorDoiUrl":"https://doi.org/10.1007/s11696-026-04886-3","workflowStages":[]},"version":"v1","identity":"rs-8904810","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8904810","identity":"rs-8904810","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}