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In recent years, the green synthesis of gold (GNPs) and silver (SNPs) nanoparticles has gained great interest among chemists and researchers. The present study reports an eco-friendly, cost-effective, rapid and easy method for the synthesis of gold and silver nanoparticles using the seed extract of Embelia ribes (SEEr) as capping and reducing agent. The synthesised GNPs and SNPs were characterised using the following techniques: UV-vis spectroscopy, DLS, HR-TEM, FT-IR and XRD. The free radical scavenging potential of GNPs and SNPs was measured by DPPH assay and Phosphomolybdenum assay. Further, the antimicrobial activity against two micro-organisms were tested using disc diffusion method and cytotoxicity of GNPs and SNPs was determined against MCF-7 cell lines at different concentrations by MTT assay. Both the GNPs and SNPs prepared from E. ribes comparatively showed promising results thereby proving their clinical importance.

The chemical content of plant excerpts can be efficiently employed to reduce the metal ions to nanoparticles in the one-pot green production method. Here, green production of silver nanoparticles (AC-AgNPs) is performed by means of Allium cepa var. Aggregatum (shallot) extract as a stabilizer and reducer. The shape, size, and morphology of resultant AC-AgNPs are examined by optical spectroscopy analysis such as UV for nucleation and coalescence processes of the AC-AgNPs. Through FTIR functional group is determined and through DLS size is defined, it was confirmed that metallic AgNPs were successfully synthesized through the green synthesis route, and these results agreed well with the results obtained in the XRD pattern along with TEM spectroscopy, where the TEM images confirm the formation of sphere-like nanostructures along with SAED analysis. The chemical characterization is performed with XPS; the obtained molecular species in the materials are determined from the energy profile. Antioxidant activity of AC-AgNPs versus DPPH substrate is carried out. Antibacterial activity is well established against Gram-negative and Gram-positive organisms. Cell viability is accomplished, followed by an MTT assay, and a cytotoxicity assay of AC-AgNPs on MCF—7 cell lines is also carried out. Highlights: (1). This study highlights the eco-friendly synthesis of silver nanoparticles from Allium cepa var. Aggregatum Natural Extract. (2). The synthesized AC-AgNPs were characterized by UV-VIS, FT-IR, XRD, TEM, and XPS. (3). The synthesized nanoparticles were well dispersed in nature and the size range of 35 ± 8 nm. (4). The anti-candidal activity of biosynthesized silver nanoparticles was evaluated against the following Gram-Negative organisms: Escherichia coli (E. coli), and the following Gram-positive organisms: Staphylococcus aureus strains. The biosynthesized AC-AgNPs showed enhanced antiseptic features anti both Gram-positive and negative organisms. (5). Besides, the in vitro cytotoxic outcomes of AC-AgNPs were assessed versus MCF-7 cancerous cells, and the reduction in the feasibility of cancer cells was established via MTT assay, which suggests potential biomedical applications.

Nanotechnology is a branch of science and engineering dedicated to materials, having dimensions in the order of nanometer scale and it has been widely used for the development of more efficient technology. Nanoparticles offer many benefits to bulk particles such as increased surface-to-volume ratio, and increased magnetic properties. In recent years, nanotechnology has been embraced by industrial sectors due to its applications in the field of electronic storage systems, biotechnology, magnetic separation and pre concentration of target analytes, targeted drug delivery, and vehicles for gene and drug delivery. Over the year’s nanomaterials such as nanoparticles, nanoclusters, nanoreods, nanoshells, and nanocages have been continuously used and modified to enable their use as a diagnostic and therapeutic agent in biomedical applications. Thus, In this chapter, introduction to metal nanoparticles, synthesis (Chemical and green synthesis) and biomedical application silver nanoparticles are presented.

Silver nanoparticles (AgNPs), due to their interesting properties and many potential applications have attracted enormous interests in recent years. An attempt has been made in this present study to synthesize AgNPs through biological reduction of silver nitrate, with leaf extract of Hyptis suaveolens (L) Poit serving as a reducing agent. AgNPs formed were characterized with spectral (UV-Vis, XRD, FTIR) and electron microscopic investigations. Dispersed spherical nanosilver particles in the range of 2 nm-85 nm were observed through microscopic analysis and the crystalline nature was evidenced through XRD analyses. Anticandidal activity of biosynthesised AgNPs was evaluated against two Candida albicans strains. The minimum inhibitory concentration (MIC) values for AgNPs against the two clinical strains were 0.27 � 0.03 μg/ml and 0.97 � 0.13 μg/ml. AgNPs were found to be more effective than the amphotericin-B used as control against the strains of the test pathogens. Scanning electron microscopic (SEM) analyses of the Candida cells treated with AgNPs shows change in the surface morphology, suggesting cell wall disruption to be a potential mode of anticandidal activity. Based on our observations, AgNPs synthesized with leaf extract of Hyptis suaveolens could be potentially used in combating candidal infections.

An attempt was made to synthesize zinc oxide gum white nanoparticles (ZnO-GWNPs) by the greenway approach using Aegle marmelos (Bael fruit) juice extract as a capping and reducing agent. Synthesis of ZnO-GWNPs by greener approach is safer, more economical, more energy-efficient, eco-friendlier, and less toxic than chemically synthesized counterparts. The optical properties of the ZnO-GWNPs were ascertained through UV-Vis spectroscopy, Fourier Transform-Infrared (FT-IR), X-ray diffraction (XRD), High-resolution transmittance electron microscopy (HRTEM). A characteristic absorption peak at 385nm confirmed the presence of ZnO-GWNP using UV-Vis spectroscopy. FTIR spectrum revealed that the characteristic absorption peak of the Zn-O bond was observed at 467 cm-1. The XRD result for the ZnO showed the tendency of the three most intense diffraction peaks. The average crystallite size ZnO NPs at scattering angle (2θ) 22.89 and 32.15 was 39.14 and 26.08 nm and it showed the presence of miller indices of (100), (002), (101), (102) respectively. The EDX spectrum gave strong signals for zinc and oxygen indicating the occurrence of the nanoparticles in their oxide form rather than the pure zinc form. The SEM image showed the surface morphology of ZnO-GW NPs and the HR-TEM image showed the crystalline nature of ZnO-GW NPs. Cytotoxicity study of ZnO-GW NPs was determined against MCF-7 cell lines and the IC50 values were found to be 40 µg/mL and 60 µg/mL at 24 h and 48 h respectively.

Magnesium oxide nanoparticles (MgONPs) synthesized by efficient green approach have unique physiochemical properties. In this study, MgONPs are synthesized with bract extract of Musa acuminate, an agro waste. The surface plasmon resonance at 450 nm in UV spectrum and FTIR peaks at 601 and 890 cm−1 confirmed the presence of MgONPs. XRD pattern revealed high crystallinity of the nanoparticles with an intense orientation peak at 111, and the size was 13 nm. The particles were spherical with an average size of 24.85 nm. The elemental percentage of magnesium and oxygen were 68.55% and 31.45%. MgONPs had antibacterial activity against Bacillus subtilis, Escherichia coli, Vibrio harveyi, Vibrio parahemolyticus, and Staphylococcus aureus with MIC, 6 μg/mL. The IC50 value for MCF‐7 cell was 113.56 μg/mL, and the normal cell line was 785.69 μg/mL. The NPs also exhibited hemolytic features in a dose‐dependent manner. The MgONPs exhibited photocatalytic degradation of methyl violet, CBB G‐250, and malachite green in 60 min duration. MgONPs had promising antibacterial, cytotoxic, hemolytic, photocatalytic, and seed germination activity. They have the potential to serve as an additive in a variety of biological applications.

Novel coronavirus pneumonia (COVID-19) is a respiratory infection caused by infecting lungs and respiratory pathways which has rapidly spread to 216 countries. It is causing serious harm to the world’s entire population and a huge social burden, which can spread mainly by droplets produced during coughing and sneezing from animal to animal or human to human. There were no drugs or vaccines available as of May 2020. Though the severity and infectious behavior and mortality rate of COVID-19 led to the discovery of various vaccines and drugs that are available to control COVID-19 pandemic. India has two vaccines: Covishield and Covaxin approved by the Government of India on 2nd January 2021. Of this sudden and lethal disease, the traditional Indian siddha medicine was proficient as an alternative source, in performing differentiation with fewer side effects and better ability to prevent and control. In this article, we have comprehensively analyzed the case study and the efficacy of Indian Siddha medicine Kabasura Kudineer chooranam. Naturally occurring Indian Siddha medicinal (Kabasura Kudineer chooranam) compounds and its treatment as prevention measures so as to provide strategy and suggestions for the disease COVID-19 are discussed.