Antibacterial Effects of Biosynthesized Silver Nanoparticles on Surface Ultrastructure and Nanomechanical Properties of Gram-Negative Bacteria viz. Escherichia coli and Pseudomonas aeruginosa
| Autor: | Sujoy K. Das, Thanusu Parandhaman, Baskaran Ramalingam |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Silver
Gram-negative bacteria Materials science Rhizopus oryzae Analytical chemistry Metal Nanoparticles 02 engineering and technology 010402 general chemistry medicine.disease_cause 01 natural sciences Silver nanoparticle chemistry.chemical_compound Microscopy Electron Transmission Dynamic light scattering Escherichia coli medicine General Materials Science Cell-Free System biology 021001 nanoscience & nanotechnology biology.organism_classification Anti-Bacterial Agents 0104 chemical sciences Silver nitrate chemistry Pseudomonas aeruginosa Silver Nitrate 0210 nano-technology Antibacterial activity Rhizopus Bacteria Nuclear chemistry |
| Zdroj: | ACS Applied Materials & Interfaces. 8:4963-4976 |
| ISSN: | 1944-8252 1944-8244 |
| Popis: | Understanding the interactions of silver nanoparticles (AgNPs) with the cell surface is crucial for the evaluation of bactericidal activity and for advanced biomedical and environmental applications. Biosynthesis of AgNPs was carried out through in situ reduction of silver nitrate (AgNO3) by cell free protein of Rhizopus oryzae and the synthesized AgNPs was characterized by UV-vis spectroscopy, high resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), ζ-potential analysis, and FTIR spectroscopy. The HRTEM measurement confirmed the formation of 7.1 ± 1.2 nm AgNPs, whereas DLS study demonstrated average hydrodynamic size of AgNPs as 9.1 ± 1.6 nm. The antibacterial activity of the biosynthesized AgNPs (ζ = -17.1 ± 1.2 mV) was evaluated against Gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa. The results showed that AgNPs exhibited concentration dependent antibacterial activity and 100% killing of E. coli and P. aeruginosa achieved when the cells were treated with 4.5 and 2.7 μg/mL AgNPs, respectively for 4 h. Furthermore, the intracellular reactive oxygen species (ROS) production suppressed the antioxidant defense and exerted mechanical damage to the membrane. AgNPs also induced surface charge neutralization and altered of the cell membrane permeability causing nonviability of the cells. Atomic force microscopy (AFM) studies depicted alteration of ultrastructural and nanomechanical properties of the cell surface following interaction with AgNPs, whereas FTIR spectroscopic analysis demonstrated that cell membrane of the treated cells underwent an order-to-disorder transition during the killing process and chemical composition of the cell membrane including fatty acids, proteins, and carbohydrates was decomposed following interaction with AgNPs. |
| Databáze: | OpenAIRE |
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