Green synthesis of polydopamine-functionalized silver nanoparticles conjugated with Ceftazidime: in silico and experimental approach for combating antibiotic-resistant bacteria and reducing toxicity

The environmental and clinical burden of antibiotic-resistant bacteria necessitates innovative and sustainable antimicrobial strategies. In this study, silver nanoparticles (AgNPs) were synthesized using Agastache rugosa (A. rugosa) leaf extract, a green synthesis approach that aligns with environmental sustainability. Surface modifications of AgNPs were carried out using poly(vinylpyrrolidone) (PVP) and polydopamine (PDA), followed by conjugation with the antibiotic Ceftazidime (Cfz) to enhance antibacterial efficacy. Comprehensive characterization through UV–Vis spectroscopy, FT–IR, and TEM confirmed well-defined nanostructures with average sizes of 18.52 nm (AgNPs) and 25.3 nm (PDA@AgNPs). The PDA@AgNPs-Cfz nanocomposite exhibited superior antibacterial and antibiofilm activity against Pseudomonas aeruginosa (P. aeruginosa), achieving significantly improved minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values compared to AgNPs or Cfz alone. Toxicity assays indicated reduced cytotoxicity of PDA@AgNPs-Cfz relative to unmodified AgNPs towards zebrafish embryos. Molecular docking studies further elucidated the interactions of bioactive compounds from A. rugosa with key bacterial proteins, providing insights into their antibacterial mechanisms. This research highlights a synergistic antimicrobial approach that combines green synthesis, advanced nanomaterial engineering, and molecular insights. The findings underscore the potential of PDA@AgNPs conjugated with Cfz as a promising strategy to address antibiotic resistance and bacterial infections in an environment-friendly manner. This study contributes to the development of sustainable, innovative solutions for environmental and clinical challenges associated with microbial contamination.