Hybrid nanoparticles combining nanoselenium-mediated Carica papaya extract and trimethyl chitosan for combating clinical multidrug-resistant bacteria.

Multidrug-resistant bacterial infections pose a significant threat to human health, prompting the exploration of innovative solutions. In this study, a new series of antibacterial hybrid nanoparticles (HNPs) were developed. The HNPs are based on a combination of selenium nanoparticles (SeNPs), synthesized using Carica papaya leaf extract, and chitosan (CS/SeHNPs) or trimethyl chitosan (TMC/SeHNPs), respectively. Comprehensive characterization using UV-Vis, FTIR, XRD, SEM-EDX, DLS, TEM, and DSC confirmed the structure and properties of the developed HNPs. SeNPs, CS/SeHNPs, and TMC/SeHNPs showed average hydrodynamic size of 78.8, 91.3, and 122 nm, and zeta potentials of -6.35 mV, +32.8 mV, and +54.8 mV, respectively. Biological assessments were conducted, including antibacterial and antibiofilm assays against clinical strains (E. coli, S. aureus, and K. pneumoniae), along with antioxidant activity. TMC/SeHNPs demonstrated superior performance compared to SeNPs and CS/SeHNPs with the lowest minimum inhibition concentrations (MIC) against S. aureus and K. pneumoniae (3.9 μg/mL) and 62.5 μg/mL against E. coli in addition to robust antibiofilm activity. Furthermore, the TMC/SeHNPs exhibited potent DPPH free radical scavenging ability and demonstrated good biocompatibility, as evidenced by cell viability assays on HFB4 cells. Overall, TMC/SeHNPs emerged as promising candidates in nanomedicine, offering high antioxidant, antibacterial, and antibiofilm activities alongside excellent biocompatibility.