Green biosynthesis of silver nanoparticles with Eryngium caucasicum Trautv aqueous extract

Silver Nanoparticles Biosynthesis, Characterization, Antimicrobial Activities, Applications, Cytotoxicity and Safety Issues: An Updated Review

Rapid advances in nanotechnology have led to its emergence as a tool for the development of green synthesized noble metal nanoparticles, especially silver nanoparticles (AgNPs), for applications in diverse fields such as human health, the environment and industry. The importance of AgNPs is because of their unique physicochemical and antimicrobial properties, with a myriad of activities that are applicable in various fields, including the pharmaceutical industry. Countries with high biodiversity require the collection and transformation of information about biological assets into processes, associations, methods and tools that must be combined with the sustainable utilization of biological diversity. Therefore, this review paper discusses the applicable studies of the biosynthesis of AgNPs and their antimicrobial activities towards microorganisms in different areas viz. medicine and agriculture. The confirmed antiviral properties of AgNPs promote their applicability for SARS-CoV-2 treatment, based on assimilating the virus’ activities with those of similar viruses via in vivo studies. In this review, an insight into the cytotoxicity and safety issues of AgNPs, along with their future prospects, is also provided.

GC-MS based lemon grass metabolite analysis involved in the synthesis of silver nanoparticles and evaluation of photo-catalytic degradation of methylene blue

Silver nanoparticles (AgNPs) is of great importance to scientific community due to their plethora of applications. Several plant extracts have been reported for synthesis of AgNPs. In this study, lemon grass was used as a reducing and capping agent to prepare AgNPs. The formation of AgNPs was confirmed by using UV-Vis spectra as AgNPs show a characteristic peak around 400 nm. Effect of pH, temperature and lemon grass extract to silver nitrate ratio was optimized using response surface methodology (RSM). Characterization of AgNPs was done using X-Ray Diffraction (XRD), Energy Dispersive X-Ray spectroscopy (EDX), Trasmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). Gas Chromatography-Mass spectrometry (GC-MS), Energy Dispersive X-Ray spectroscopy and Fourier Transform-Infrared (FT-IR) spectroscopic analysis showed involvement of metabolites of lemon grass in the formation of AgNPs. Photo-catalytic activity of synthesized AgNPs was evaluated through degradation of organic pollutant methylene blue dye.

Synthesis of nanocomposite hydrogel based carboxymethyl starch/polyvinyl alcohol/nanosilver for biomedical materials

Treatment of infections using wound dressing integrated with multiple functions such as antibacterial activity, non-toxicity, and good mechanical properties has attracted much attention. In this study, carboxymethyl starch/polyvinyl alcohol/citric acid (CMS/PVA/CA) hydrogels containing silver nanoparticles (AgNPs) were prepared. The CMS, PVA and CA were used as polymer matrix and bio-based reducing agents for green synthesis of AgNPs. Silver nitrate (AgNO₃) concentrations of 50, 100, and 150 mM were used to obtain nanocomposite hydrogels containing different AgNPs concentrations (AgNPs-50, AgNPs-100 and AgNPs-150, respectively). The minimum inhibitory concentration against E. coli and S. aureus was observed in CMS/PVA/CA hydrogels containing AgNPs-50. Uniform dispersion of AgNPs-100 in the hydrogel provided the highest storage modulus at 56.4 kPa. AgNPs-loaded hydrogels showed low toxicity to human fibroblast cells indicating good biocompatibility. Incorporation of AgNPs demonstrated an enhancement in antibacterial properties and overall mechanical properties, which makes these nanocomposite hydrogels attractive as novel wound dressing materials.