Chitosan-stabilized Ag–Ni bimetallic nanoparticles for quantitative antibacterial evaluation and prospective wound-coating applications

Abstract

Bimetallic silver–nickel nanoparticles (Ag–Ni BMNPs) stabilized with chitosan were synthesized and systematically characterized to evaluate their antibacterial properties and potential for proof-of-concept wound-coating applications. The synthesized nanoparticles were characterized using UV–Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), elemental mapping, dynamic light scattering (DLS), zeta-potential analysis, Brunauer–Emmett–Teller (BET) surface-area analysis, and thermogravimetric analysis (TGA). Additionally, X-ray photoelectron spectroscopy (XPS) confirmed the presence of Ag and Ni on the NP surface: mostly metallic Ag and both metallic Ni and Ni-oxide species. The NPs exhibited nanoscale morphology and moderate colloidal stability, with chitosan contributing to their stabilization. The antibacterial activity was tested against two Gram-positive ( Staphylococcus aureus and Bacillus subtilis ) and two Gram-negative ( Escherichia coli and Pseudomonas aeruginosa ) representative strains. Ag–Ni BMNPs exhibited considerably more antibacterial activity than the respective monometallic AgNPs and NiNPs based on zone of inhibition and minimum inhibitory concentration (MIC) analysis ( p  < 0.05). For proof-of-concept coating applications, Ag–Ni BMNPs were incorporated into chitosan-based coatings and evaluated for antibacterial performance, coating integrity, and Ag + /Ni 2+ release using inductively coupled plasma optical emission spectroscopy (ICP-OES). The coatings exhibited in vitro antibacterial activity, showed no loss of physical integrity during PBS exposure, and showed time-dependent metal-ion release under the tested conditions. The results presented herein confirm the coating’s potential as a proof-of-concept platform and chitosan-stabilized Ag–Ni BMNPs as a promising material for antibacterial applications. However, further investigation of in vitro and in vivo cytotoxicity, hemocompatibility, biocompatibility, and wound-healing efficacy is needed before considering biomedical or clinical applications.