Therapeutic efficacy of bovine serum albumin-gold nanocluster against antibiotic-resistant bacterial susceptibility

Biofilm formation is one of the most vital risk factors for antimicrobial resistance in bacteria. In the present study we investigated the effect of bovine serum albumin-gold nanoclusters (BSA-GNCs) against antibiotic-resistant bacterial susceptibility. BSA-GNCs was synthesized by adding HAuCl ₄ and BSA as a capping agent. BSA-GNCs were characterized by UV-Visible spectrophotometer, FTIR, Zeta sizer, SEM-EDX and TEM analysis. Antibacterial activity from antibiotic-resistant bacterial strains Klebsiella pneumoniae, Streptococcus aureus , and non-resistant bacterial strains Pseudomonas aeruginosa and Enterococcus faecalis were assessed using the disc diffusion method. The pellets of the control and BSA-GNCs treated bacteria were procured for transmission electron microscopy. The ultrastructural images of the bacteria were captured using a bottom mounted 15-megapixel Quemesa camera with iTEM software. A peak at λmax = 550nm from UV-Visible spectrophotometer spectrum was confirmed the formation of gold nanoclusters. FTIR peaks were found at 598.33, 1102.79, 1261.21, 1637.84, 2923.54 & 3430.76cm ^− 1 , and average hydrodynamic particle size distribution peaks were 22.72nm. BSA-GNCs were homogenous as well as cluster nature. BSA-GNC (20µL/disc) treatment inhibited the growth zone of the bacteria ( KP 13.17 ± 1.32, SA 16.67 ± 1.46, PA 23.17 ± 1.82 and EF 25.67 ± 1.93 mm) at 24 hours. The BSA-GNCs treated bacteria accommodating shrunken, stranded and degenerated cytoplasm. The degeneration of the bacteria was more severe in antibiotic susceptible bacteria than antibiotic resistant bacteria. BSA-GNCs attenuate the transport of essential elements to the bacteria leading to the degeneration of the cytoplasm followed by the disintegration of the plasma membrane, cell walls and extinguishing the bacteria.