Introduction: The global rise of antibiotic-resistant and biofilm-forming pathogens necessitates the development of functional biomaterials with non-antibiotic antimicrobial mechanisms. Nano-enabled biomaterials combining biocompatible polymers and metallic nanoparticles offer promising strategies for inhibiting microbial growth, biofilm formation, and virulence without inducing cytotoxicity.
Methods: Gold nanoparticles were synthesized using maltol as a reducing agent and subsequently coated with fish gelatin to produce Mal-AuNPs-Gel. Different tools like UV–Vis spectroscopy, FTIR, XRD, FE-TEM, SAED, EDS, zeta potential analysis, and dynamic light scattering were used. Antimicrobial activity was evaluated against bacterial and fungal pathogens by determining MICs. Crystal violet and the CFU method were employed to quantify the single- and mixed-species biofilm. Antivirulence activity was assessed by analyzing hemolysis, siderophore production, protease activity, and motility. RT-PCR was used to check the gene expression, whereas in vitro cytotoxicity and in vivo phytotoxicity assays were used to check the biocompatibility.
Results: Physicochemical analysis confirmed successful NP synthesis with a distinct UV-Vis absorption peak at 555 nm, spherical-to-irregular crystalline morphology, and an average particle size of 111–113 nm. Gelatin coating reduced the zeta potential from −27.68 mV to −2.3 mV, indicating effective surface functionalization. Long-term stability studies showed only a slight increase in particle size after two months. The Mal-AuNPs-Gel demonstrated enhanced antimicrobial activity against Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Listeria monocytogenes, Escherichia coli, and Candida albicans. Mal-AuNPs-Gel significantly inhibited biofilm formation and suppressed virulence traits of P. aeruginosa, accompanied by the downregulation of genes involved in multiple virulence factors. Cytotoxicity/phytotoxicity assays confirmed good biocompatibility at effective concentrations.
Conclusion: This work highlights fish gelatin-based nanobiomaterials as multifunctional antimicrobial agents with strong potential for biomedical and surface-related applications to combat biofilm-forming antibiotic-resistant pathogens.
Funding: This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education (RS-2023-00241461 and RS-2025-00555808).
