Enhanced Antibacterial Performance of PANI–CdS/Au Nanocomposites Synthesized by Chemical Routes

Polyaniline-cadmium sulfide-gold (PANI-CdS-Au) nanocomposites were synthesized with varying Au loadings (0.023, 0.046, 0.092)wt% to enhance antibacterial performance. Structural (FTIR, XRD) and morphological (FE-SEM) analyses confirmed successful formation, strong interactions among components, and homogeneous nanoparticle dispersion. UV–Vis spectra revealed gold surface plasmon resonance and polaronic transitions consistent with PANI emeraldine base. XRD results showed the expected wurtzite CdS and fcc Au phases. Agar well diffusion tests against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) demonstrated that the 0.092 wt% of Au composite produced the largest inhibition zones at 100 µg mL⁻¹ (E. coli: 36 mm; S. aureus: 24 mm), with the same trend at 25 µg mL⁻¹. These results position PANI-CdS-Au nanocomposites as promising antibacterial materials; additional cytotoxicity assays are recommended for biomedical translation.