Emerging Trends in Advanced Translational Applications of Silver Nanoparticles: A Progressing Dawn of Nanotechnology.

Nanoscience has emerged as a fascinating field of science, with its implementation in multiple applications in the form of nanotechnology. Nanotechnology has recently been more impactful in diverse sectors such as the pharmaceutical industry, agriculture sector, and food market. The peculiar properties which make nanoparticles as an asset are their large surface area and their size, which ranges between 1 and 100 nanometers (nm). Various technologies, such as chemical and biological processes, are being used to synthesize nanoparticles. The green chemistry route has become extremely popular due to its use in the synthesis of nanoparticles. Nanomaterials are versatile and impactful in different day to day applications, resulting in their increased utilization and distribution in human cells, tissues, and organs. Owing to the deployment of nanoparticles at a high demand, the need to produce nanoparticles has raised concerns regarding environmentally friendly processes. These processes are meant to produce nanomaterials with improved physiochemical properties that can have significant uses in the fields of medicine, physics, and biochemistry. Among a plethora of nanomaterials, silver nanoparticles have emerged as the most investigated and used nanoparticle. Silver nanoparticles (AgNPs) have become vital entities of study due to their distinctive properties which the scientific society aims to investigate the uses of. The current review addresses the modern expansion of AgNP synthesis, characterization, and mechanism, as well as global applications of AgNPs and their limitations.

Antibacterial efficacy of facile cyanobacterial silver nanoparticles inferred by antioxidant mechanism.

Nanoparticles (NPs) have gained importance in technological advances owing to their user friendly enhanced and efficient physical, chemical, and biological characteristics compared to their bulk counterparts. Biological synthesis of NPs by using a microorganism, enzymes, or plant extracts offers a greener and eco-friendly approach besides many advantages over physical or chemical approaches. This study reports the biosynthesis of silver nanoparticles (AgNPs) using Nostoc muscorum NCCU 442 aqueous extract as the reducing and capping agent for AgNPs synthesis. The synthesized nanoparticles were characterized by UV-VIS spectrum, SEM, EDS, TEM, AFM, DLS and XRD. Results showed distinguishing polycrystalline nature of synthesized AgNPs with surface plasmon significant band in the size range of 6-45nm with average 30 size nm. FT-IR study revealed the role of secondary metabolites present in aqueous extract for the synthesis of AgNPs. Biological activities of purified AgNPs as antioxidant and antibacterial potential showed the highest antibacterial activity against Staphylococcus aureus MTCC 902.

Facile green bio-fabricated silver nanoparticles from Microchaete infer dose-dependent antioxidant and anti-proliferative activity to mediate cellular apoptosis.

With the rapid development of nanotechnology, much has been anticipated with silver nanoparticles (AgNPs) due to their extensive industrial and commercial applications. However, it has raised concerns over environmental safety and human health effects. In this study, AgNPs were bio-fabricated using aqueous extract of Microchaete and their medical applications like antioxidant, anti-proliferative, and apoptosis were done. The biosynthesis of AgNPs was continuously followed by UV-vis spectrophotometric analysis. The physiochemical properties like shape, size, crystallinity, and polydispersity of the nanoparticles were determined by Scanning Electron Microscopy (SEM) along with EDX, Transmission Electron Microscope (TEM), Atomic Force Microscope (AFM), dynamic light scattering (DLS), and X-Ray Diffraction (XRD). Biosynthesized 7.0 nm sized AgNPs with the crystalline structure (crystalline size 4.8 nm) having a hydrodynamic diameter of 38.74 ± 2.6 nm was achieved due to the involvement of reducing agents present in the cyanobacterial extract. The IC50 values of the AgNPs were evaluated as 75 µg/ml and 79.41 µg/ml with HepG2 and MCF-7 cell lines. Different in-vitro cellular assays investigated in the present study exhibited antioxidant, anti-proliferative, and apoptotic activities. Probably delayed apoptosis in HepG2 and MCF-7 is due to better antioxidant activities of Microchaete based AgNPs.

Cyanobacteria as a bioreactor for synthesis of silver nanoparticles-an effect of different reaction conditions on the size of nanoparticles and their dye decolorization ability.

The green synthesis of metallic nanoparticles has paved the way for improving and protecting the environment by decreasing the use of toxic chemicals and eliminating biological risks in biomedical applications. Biological synthesis of metal nanoparticles is gaining more importance due to simplicity, rapid rate of synthesis and eco-friendliness. In the present investigation cyanobacterial (Microchaete NCCU-342) cell free aqueous extract has been used for optimizing biosynthesis of silver nanoparticles (AgNP). The optimized reaction parameters for efficient synthesis of AgNP were: biomass quantity of 80 µg/ml, pH 5.5, 60 °C temperature, duration of 60 min UV light exposure and 1 mM AgNO3 concentration. AgNP was characterized by UV-Visible Spectrophotometery, Transmission Electron Microscopy and Dynamic light scattering. The smallest nanoparticles (obtained from biomass parameter were spherical, polydisperessed and in the range of 60-80 nm) were characterized further in a degradation study of azo dye methyl red. Degradation of methyl red within 2 h was more with AgNP (84.60%) as compared to cyanobacterial extract (49.80%).

Screening of cyanobacterial extracts for synthesis of silver nanoparticles.

Improvement of reliable and eco-friendly process for synthesis of metallic nanoparticles is a significant step in the field of application nanotechnology. One approach that shows vast potential is based on the biosynthesis of nanoparticles using micro-organisms. In this study, biosynthesis of silver nanoparticles (AgNP) using 30 cyanobacteria were investigated. Cyanobacterial aqueous extracts were subjected to AgNP synthesis at 30 °C. Scanning of these aqueous extracts containing AgNP in UV-Visible range showed single peak. The λ max for different extracts varied and ranged between 440 and 490 nm that correspond to the "plasmon absorbance" of AgNP. Micrographs from scanning electron microscope of AgNP from cyanobacterial extracts showed that though synthesis of nanoparticles occurred in all strains but their reaction time, shape and size varied. Majority of the nanoparticles were spherical. Time taken for induction of nanoparticles synthesis by cyanobacterial extracts ranged from 30 to 360 h and their size from 38 to 88 nm. In terms of size Cylindrospermum stagnale NCCU-104 was the best organism with 38 and 40 nm. But in terms of time Microcheate sp. NCCU-342 was the best organism as it took 30 h for AgNP synthesis.