Enzybiotic-mediated antimicrobial functionalization of polyhydroxyalkanoate nanoparticles

Background: Increasing antibiotic resistance is depleting the available arsenal of these conventional antimicrobials, thus making the development of alternative antibacterial agents a priority for biomedical research. This is the case for Streptococcus penumoniae , a severe respiratory pathogen which, upon colonization of the lung alveoli below the lung surfactant layer (LS), causes community-acquired pneumonia. One of the alternative approaches is the use of enzybiotics, phage-encoded peptidoglycan hydrolases that degrade the bacterial cell wall, thus leading to their death by osmotic shock. To meet therapeutic parameters such as longer in vivo half-life or targeted activity release, the design of enzybiotic formulations is required. Polyhydroxyalkanoates (PHAs) nanoparticles (NPs), present some ideal properties as biomedical nanocarriers such as their inherent biocompatibility, biodegradability, and ability to be vehiculized through hydrophobic barriers, including the lung surfactant (LS). Here, we develop PHA NPs as a platform for the immobilization of enzybiotics against S. pneumoniae via a minimal PHA affinity tag. Results In this study, we tagged the Cpl-711 enzybiotic, which specifically targets S. pneumoniae , with the minimal PHA affinity peptide MinP, resulting in the M711 protein. Then, a PHA nanoparticulate suspension with adequate physicochemical properties for pulmonary delivery was formulated, and M711 was immobilized on their surface. Finally, we assessed the antipneumococcal activity of the nanosystem against planktonic and sessile forms of the pathogen. The resulting pioneer nanosystem displayed sustained antimicrobial activity against free cells, and effectively disaggregated S. pneumoniae biofilms. Conclusions Our findings indicate tag-mediated immobilization of enzybiotics as an effective method for the antimicrobial functionalization of PHA NPs. This straightforward approach may be extrapolated to other enzybiotics (or cargo proteins) with other specificities, highlighting the versatility of the system