researcher, National Research Centre
Green Approach Synthesis of Ag Nanorod via Cellulose Nanocrystal and their Cytotoxicity assessment
Since the last decades, building small structures for advanced materials design and devices with high performance became one of the basic goals of nanoscience and nanotechnology. In this regard, anisotropic inorganic nanostructured materials are particularly attractive great interest as building blocks for such purposes, due to their unique optical, biological, electronic, magnetic, and catalytic properties. Herein, this research addresses a new innovative approach for one-pot rapid synthesis of highly stabilized silver nanorods in powder form at concentration as high as feasible to be proposed in large-scale production via novel mediator, viz., cellulose nanocrystals (CNC). the best of our knowledge, this paper is the ﬁrst contribution in utilization of CNC without modification in preparation of nanoparticles, in particular, silver nanorods. CNC is considered as a green biopolymer extracted from renewable sources which is biodegradable and non-toxic to humans and environment. For the first time, CNC without any surface modification in the presence of alkali is acting as both reducing and stabilizing agent for assembling of Ag nanorods. Extraction of CNC from cotton is carried out as per to acid hydrolysis (H2SO4 60% w/w) technique. Three different concentrations of silver nitrate are used in the assembling of Ag nanorods. Thorough assessments of Ag nanorods formation, structural and morphological characteristics of Ag nanorods were investigated by making use of UV–vis spectroscopy, TEM, DLS, AFM and X-ray diffraction(XRD) analysis. Also, the antibacterial activity and cytotoxicity of Ag nanorod were investigated. Research outputs signify that, Ag nanorods has been successfully prepared through an effectively approach by virtue of the textural feature of CNC as a mediator. Results revealed the great tendency of CNC toward reducing and stabilizing the as formed Ag nanorods even at high concentration. Regardless to concentration of AgNO3 used, the average sizes of Ag nanorods formed are in the range of 10-30nm higher concentration. Results also demonstrated that Ag nanorods have not merely remarkably antibacterial activity towards Gram-positive and Gram-negative bacteria, but safe for using in human life, which exhibited no effect on eukaryotic cells. Comparing these findings to conventual methods, CNC mediator provided Ag nanorod in powder form with facile, rapid, environmentally safe and industrial feasible for quick handling and transportation.
Abstract: Metallic nanoparticles (such as gold and silver) have been intensely studied for wound healing applications due to their ability to be easily functionalized, possess antibacterial properties, and their strong potential for targeted drug release. In this study, rod-shaped silver nanorods (AgNRs) and gold nanorods (AuNRs) were fabricated by electron beam physical vapor deposition (EBPVD), and their cytotoxicity toward human skin fibroblasts were assessed and compared to sphere-shaped silver nanospheres (AgNSs) and gold nanospheres (AuNSs). Results showed that the 39.94 nm AgNSs showed the greatest toxicity with fibroblast cells followed by the 61.06 nm AuNSs, ∼556 nm × 47 nm (11.8:1 aspect ratio) AgNRs, and the ∼534 nm × 65 nm (8.2:1 aspect ratio) AuNRs demonstrated the least amount of toxicity. The calculated IC50 (50% inhibitory concentration) value for the AgNRs exposed to fibroblasts was greater after 4 days of exposure (387.3 μg mL(-1)) compared to the AgNSs and AuNSs (4.3 and 23.4 μg mL(-1), respectively), indicating that these spherical metallic nanoparticles displayed a greater toxicity to fibroblast cells. The IC50 value could not be measured for the AuNRs due to an incomplete dose response curve. The reduced cell toxicity with the presently developed rod-shaped nanoparticles suggests that they may be promising materials for use in numerous biomedical applications.
Pub.: 09 Jun '15, Pinned: 28 Jul '17
Abstract: Dental caries is a widespread disease mainly caused by the anaerobic oral pathogen Streptococcus mutans (S. mutans). Ag/ZnO nanocomposite is an efficient antibacterial agent because of its high antibacterial activity and low cytotoxicity. In this study, rod-like Ag/ZnO nanocomposite was synthesized through a deposition-precipitation method and characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The activity of Ag/ZnO nanocomposite against S. mutans was evaluated by determining the minimal inhibitory concentration, minimum bactericidal concentration and growth inhibition curve. The results showed that Ag/ZnO nanocomposite displayed higher activity against S. mutans compared with pure ZnO nanorods. Moreover, the antibacterial mechanism was investigated by determining the bacterial membrane potential, release of K(+), intracellular reactive oxygen generation and lipid peroxidation. Disruption of membrane function and oxidation of biomacromolecules played important role in the antibacterial action of Ag/ZnO nanocomposite. This work proposes a potentially effective dental antibacterial agent against the dental caries-causing S. mutans.
Pub.: 04 Jan '17, Pinned: 28 Jul '17
Abstract: Poly(lactic-co-glycolic acid)/Ag/ZnO nanorods coating were successfully prepared on the surface of Ti metallic implants using a hydrothermal method and subsequent spin-coating of mixtures of poly(lactic-co-glycolic acid) and silver nanoparticles. The poly(lactic-co-glycolic acid)/Ag/ZnO nanorods coating exhibited excellent antibacterial efficacy of over 96% against both Staphylococcus aureus and Escherichia coli when the initial content of Ag nanoparticles was over 3wt%. In addition, the release of both silver and zinc could last for over a hundred days due to the enwrapping of poly(lactic-co-glycolic acid). Proliferation of mouse calvarial cells exhibited minimal cytotoxicity on the poly(lactic-co-glycolic acid)/Ag/ZnO coating with an initial content of Ag nanoparticles of 1wt% and 3wt%, while it inhibited cell proliferation once this value was increased to 6wt%. The results revealed that this poly(lactic-co-glycolic acid)/Ag/ZnO composite could provide a long-lasting antibacterial approach and good cytocompatibility, thus exhibiting considerable potential for biomedical application in orthopedic and dental implants with excellent self-antibacterial activity and good biocompatibility.
Pub.: 21 Jun '17, Pinned: 28 Jul '17