Shape-dependent significant physical mutilation and antibacterial mechanisms of gold nanoparticles against foodborne bacterial pathogens (Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus) at lower concentrations.

Gold nanoparticles (AuNPs) have been reported for their most desirable properties as compared to any other noble metal-based nanoparticles, which wider their applications in various fields including catalysis, bio-imaging, biosensors, medicine, biology, and material chemistry. In this study, the shape-dependent antibacterial activity of AuNPs: nanospheres (AuNSps), nanostars (AuNSts), and nanocubes (AuNCs) were investigated against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus at lower concentrations. The optical, crystallographic and morphological characterization of AuNPs was analyzed by UV-visible spectroscopy, X-ray diffraction spectroscopy, and transmission electron microscopy (TEM). Shape-dependent antibacterial qualitative and quantitative analyses revealed an effective bactericidal activity of AuNCs against the tested bacteria, followed by AuNSps and AuNSts. The study revealed that the AuNCs are effective bactericidal agents with 100% inactivation rate. The visual analysis confirmed the antibacterial activity of AuNCs and AuNSps by showing physical mutilated bacterial cells which involved cell loss, loosening of the cell wall, loss of flagella and cellular matrix. Finally, released nucleic acid was measured for the treated bacterial cells which support the physical mutilation by releasing 38 μg/mL (Pseudomonas aeruginosa) of cellular material after treating with AuNCs. It is concluded from this study that AuNPs showed the significant antibacterial property at lower concentrations. More applications can be explored including anti-infections, decontamination, and food safety.