Introduction
The development of antibiotics has played a significant role in controlling the number of bacterial infections. However, the improper use and the overuse of antibiotics led to the development of multidrug resistance in many bacteria species. Some strains have become resistant to practically all of the commonly available agents:beta-lactams, tetracyclie, aminoglycosides.
One of the promising method against drug-resistant bacteria can be surface modified materials with biocidal nanoparticles and nanocomposites. Herein, we present a nanocomposite with silver nanoparticles (Ag-NPs) on the surface of graphene oxide (GO), as a novel multifunctional antibacterial and antifungal material.
Methods
Ultrasonic technologies has been used as an effective method of coating polyurethane foils. Toxicity on Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis) and pathogenic yeast (Candida albicans) was evaluated by analysis of cell morphology, assessment of cell viability by Presto Blue assay, analysis of cell membrane integrity by LDH assay and reactive oxygen species production.
Results
Ag-NPs, GO and Ag-GO nanocomposites showed antibacterial activity that is stronger against Gram-negative bacteria (E. coli) than against Gram-positive bacteria, (S. aureus and S. epidermidis) and yeast (C. albicans). A disruption of membrane functionality from an interaction between released Ag nanoparticles/Ag+ ions and the cell membrane and extensive cell membrane damage caused by the formation of ROS ultimately causing damage to the cell due to oxidative stress. The synergistic effect between GO and Ag-NPs has reduced the Ag content without compromising the antibacterial performance.
Discusion
Silver nanoparticles can cause direct damage to the bacterial cell membrane. Bacteria may be killed by the combined bactericidal effects of the released Ag ions and Ag nanoparticles. Many studies have sought to establish a mechanism of action of antibacterial activity exhibited by silver in both its colloidal and ionic form. A disruption of membrane functionality from an interaction between released Ag+ ions and the cell membrane and extensive cell membrane damage caused by the formation of reactive oxygen species (ROS) ultimately causing damage to the cell due to oxidative stress. Foils coated with Ag-NPs and GO-Ag increased the ROS production of all tested microorganisms compared with the control group.
Carbon & graphene nanostructures , Biological & medical nanodevices and biosensors , Toxicology and risk assessment of nanomedicine systems
