Synergistic Effect of Bovine Serum Albumin–Gold Nanoclusters Against Antibiotic‐Resistant Bacterial Sustainability and Biofilm Fabrication

This study evaluated the antimicrobial and antibiofilm effects of bovine serum albumin-gold nanoclusters (BSA-GNCs) against planktonic and antibiotic-resistant bacteria. BSA-GNCs were synthesized and characterized using UV spectrofluorimetry, Fourier transform infrared spectroscopy (FTIR), zeta sizing, scanning electron microscopy (SEM)-energy-dispersive x-ray (EDX), and transmission electron microscopy (TEM) analyses. Cytotoxicity was evaluated using the MTT assay. Antimicrobial and antibiofilm activities were assessed against four bacterial strains: Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus faecalis. A characteristic UV absorption peak at 500 nm, along with a visible color change, confirmed successful GNC formation. FTIR spectra showed prominent functional groups at 598.33, 1102.79, 1261.21, 1637.84, 2923.54, and 3430.76 cm^-1, and the mean hydrodynamic diameter measured 22.72 nm. BSA-GNC exposure induced moderate cytotoxicity in HaCaT cells at concentrations above 40 µg/µL. Treatment with 40 µg/µL BSA-GNCs significantly enhanced bacterial growth inhibition zones (KP: 28 ± 2.44 mm; SA: 27.5 ± 2.45 mm; PA: 31.5 ± 1.91 mm; EF: 29.75 ± 2.5 mm) after 24 h. TEM imaging of BSA-GNC-treated bacteria revealed shrunken, disrupted cells with degenerated cytoplasm. Additionally, BSA-GNC treatment markedly reduced biofilm formation at both 24 and 48 h compared with untreated controls. These findings indicate that BSA-GNCs enhance reactive oxygen species (ROS) accumulation, leading to impaired bacterial growth and biofilm formations.