Antimicrobial behavior of biosynthesized silica–silver nanocomposite for water disinfection: A mechanistic perspective

• Published in: Journal of hazardous materials Vol. 290; pp. 117 - 126
• Main Authors: Parandhaman, Thanusu, Das, Anisha, Ramalingam, B., Samanta, Debasis, Sastry, T.P., Mandal, Asit Baran, Das, Sujoy K.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-06-2015
• Subjects: Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Bacterial Load; Disinfection - methods; DNA damage; DNA Fragmentation; DNA, Bacterial - genetics; Escherichia coli; Escherichia coli - drug effects; Hypoxia; Nanocomposites - chemistry; Oxidative stress; Particle-specific activity; Plasmids - genetics; Proteomics; Pseudomonas aeruginosa; Pseudomonas aeruginosa - drug effects; Reactive Oxygen Species; Silicon Dioxide - chemistry; Silver Compounds - chemistry; Silver Compounds - pharmacology; Silver nanomaterial; Water disinfection; Oxidative stress; Particle-specific activity; Reactive oxygen species; DNA damage; Water disinfection; Silver nanomaterial
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2015.02.061

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•Fungal protein mediated green synthesis of silver nanocomposite has been developed.•The silver nanocomposite ruptured the bacterial cell membrane and released intracellular materials.•The silver nanocomposite inhibited the respiratory chain dehydrogenase and metabolic activity of the cells.•The silver nanocomposite fragmented the DNA and down regulated protein expression.•The silver nanocomposite exhibited ROS independent particle specific antibacterial activity.
The biosynthesis of nano-silica silver nanocomposite (NSAgNC) and it is as antibacterial effect on gram-negative bacteria viz.Escherichia coli and Pseudomonas aeruginosa has been investigated for disinfection of water. The as-synthesized NSAgNC exhibited antibacterial activity in a dose dependent manner and ∼99.9% of E. coli and P. aeruginosa were killed at a concentration of 1.5mg/mL of NSAgNC (5.1wt% Ag) within 5h. The NSAgNC showed similar antibacterial activities both in oxic and anoxic conditions. The results further demonstrated that NSAgNC exhibited reactive oxygen species (ROS) independent “particle specific” antibacterial activity through multiple steps in absence of leached out Ag+ ions. The initial binding of NSAgNC on the cell wall caused loss of cell membrane integrity and leakage of cytoplasmic materials. Inhibition of respiratory chain dehydrogenase by NSAgNC caused metabolic inactivation of the cells and affecting the cell viability. Genomic and proteomic studies further demonstrated the fragmentations of both plasmid and genomic DNA and down regulation of protein expression in NSAgNC treated cells, which leading to the cell death. Thus the biosynthesized NSAgNC has great potential as disinfectant for water purification while minimizing the toxic effects.