Synthesis, characterization and biocompatibility of “green” synthesized silver nanoparticles using tea polyphenols

Abstract

Since ancient times, people have taken advantage of the antimicrobial effects of colloidal silver particles. Aside from the medical prospects, silver nanoparticles are found in a wide range of commercially available consumer products ranging from cosmetics to household cleansers. Current synthetic methods for creating silver nanoparticles typically call for potentially hazardous chemicals, extreme heat, and produce environmentally dangerous byproducts. Therefore, it is essential that novel "green" synthesis of nanoparticles becomes a reality, and it is imperative to fully analyze the potential toxic effects of these nanoparticles. In this study, we have shown that by reducing silver nitrate in solutions of tea extract or epicatechin of varying concentrations, spherical silver nanoparticles were formed that had controllable size distributions depending on the concentration of tea extract or epicatechin in the samples. Our ultra-resolution microscopy demonstrated that the nanoparticles were in fact interacting with the keratinocytes. Furthermore, evaluation of mitochondrial function (MTS) to assess cell viability and membrane integrity (LDH) in human keratinocytes showed that the silver nanoparticles were nontoxic. These results demonstrated that these nanoparicles are potentially biocompatible and warrant further evaluation in other biological systems.

Natural reducing agents for electroless nanoparticle deposition: Mild synthesis of metal/carbon nanostructured microspheres

“…Our methodology shows that this mild and environmentally benign reductant can be used for the synthesis of surface supported metal nanoparticles, thus expanding its use beyond solution based nanoparticle synthesis [31,32]. Both Ag/C and Pd/C composite microspheres were tested in order to assess their activity as heterogeneous catalysts for organic synthesis.…”

“…Recently Varma and co-workers reported on the use of coffee or tea as a reducing agent for green synthesis of metal nanoparticles [31,32]. In this work we report on the use of coffee as a low-cost, green reagent for electroless deposition at room temperature.…”

“…2a and 2b show the result of silver and palladium reduction using coffee at CM surfaces; metallic clusters can be clearly seen in the SEM images. Varma and co-workers [31,32] have shown that coffee solutions can be used to reduce M n+ to form nanoparticles; the exact identity of the reducing agent in coffee remains unclear, although it has been hypothesized that either caffeine [31] or polyphenols [32,40] could be responsible for metal reduction. In fact, previous work has shown that other components of coffee that are unrelated to caffeine have a reduction potential sufficiently negative to spontaneously reduce PdCl 4 2-and Ag(NH 3 ) 2 + ions in solution [41].…”

Safety and efficacy of composite collagen–silver nanoparticle hydrogels as tissue engineering scaffolds

“…9,10 More recently, therefore, silver nanoparticles (AgNPs) have been evaluated as a safer alternative to ionic silver. 1,[11][12][13][14][15][16][17][18][19][20] The recent work from our team showed that in comparison with silver, biomolecule-coated, photochemically-produced AgNPs can have both bactericidal and bacteriostatic properties with almost negligible cytotoxic effects. 12 We also showed that oxidation of Ag to AgO is most likely the cause of the cytotoxic effects observed with AgNPs.…”

Green Synthesis of Gold Nanoparticles Using Barberry and Saffron Extracts

“…Among them, plants are more suitable and compatible due to optimal environmental preservation, fast, simple production and high stability of particles (12,13). In addition, these organic nanoparticles can be used for molecular medicine as well as modern care in future.…”