BIOGENIC NANOPARTICLES: SYNTHESIS, CHARACTERIZATION AND ITS APPLICATIONS

Abstract

The Chapter 1 presents elaborated introduction of nanoscience and nanotechnology along with the historical prospects of the proposed work. Detailed information on synthesis of nanoparticles and various factors affecting the synthesis of metallic nanoparticles has been discussed followed by the therapeutic applications of biogenically synthesized nanoparticles. Additionally, in this chapter, the toxic effects of metallic nanoparticles on the biological system has also been discussed by highlighting the importance of toxicological assessment. This chapter also describes the detailed literature review of biogenically synthesized metallic nanoparticles along with their therapeutic applications. The Chapter 2 describes the biogenic synthesis of Chlorella minutissima silver nanoparticles (CmAgNPs) and analysed it's in vitro antioxidant and antineoplastic efficacy against Hepatocellular Carcinoma Cell Lines (HePG2) and Human Embryonic Kidney Cells (HEK-293). Cell-free supernatant of C. minutissima was utilized for the synthesis of biogenic silver nanoparticles (CmAgNPs). Synthesized biogenic CmAgNPs were characterized using several biophysical techniques (UV-Vis spectroscopy, HR-TEM, EDX, FE-SEM, XRD and AAS analysis). Estimation of carbohydrate and protein content in the C. minutissima aqueous extract (CmAe) showed them to be the key reducing and stabilizing agents for CmAgNPs formation. Electron microscopic visualization showed that synthesized CmAgNPs were spherical in shape with mean diameter ranging from 10 to 30 nm. Results obtained in this study emphasis that CmAgNPs exhibit maximum free radical scavenging activity proving it to be a more potent antioxidant agent as compared to CmAe. The mortality rate of HepG2 cells treated with CmAgNPs was observed to be 91.8 % at 120 μg/ml with IC50 value of 12.42 ±1.096 μg/ml after 48 h while no effects were detected on HEK-293 cells. Fluorescent images of HepG2 cells treated with CmAgNPs revealed the formation of apoptotic bodies, condensed nuclei and cell shrinkage indicating their effectiveness against the cancer cells. The Chapter 3 describes the use of Pterospermum acerifolium leaf extract (PALE) as a novel reducing agent for the synthesis of biogenic silver nanoparticles. These PALE silver nanoparticles (PaAgNPs) were characterized by ultraviolet-visible (UV-Vis) spectroscopy and high-resolution transmission electron (HR-TEM) analysis which indicated nanoparticles to be spherical in shape and the particle size ranging from 10-20 nm. Fourier-transform infrared spectroscopy (FTIR) analysis showed that the betulinic acid (pentacyclic triterpene) vii may be responsible for surface functionalization and has a role in PaAgNPs formation. Synthesized PaAgNPs exhibited excellent antioxidant potential when tested using antiradical (DPPH) assay. Twofold enhanced anti-inflammatory activity of PaAgNPs was observed showing a dose-dependent reduction in rats paw edema. Further, antineoplastic effects of PaAgNPs on HepG2 cells were monitored by MTT assay, DAPI, and AO-EB staining. The mortality rate of up to 94.6% was observed at 250 μg/ml with IC50 value 4.76 ± 1.1 μg/ml after 48 h. However negligible effect was detected on HEK-293 cells. Fluorescence imaging analysis revealed shrinked and condensed nuclei along with the fragmentation and formation of apoptotic bodies in PaAgNPs treated HepG2 cells. Additionally, PaAgNPs showed antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Shigella flexneri and Candida albicans using well diffusion assay. The synthesized PaAgNPs were found to be highly stable after six months as well as biocompatible for antineoplastic potential against HepG2 cell lines and exhibited lesser toxicity against normal HEK-293 cells. The investigation unveils that biogenic PaAgNPs could be exploited as effective antioxidant, anti-inflammatory, antineoplastic and antimicrobial agents. The Chapter 4 describes the therapeutic effectiveness of other biogenically synthesized Woodfordia fruticosa nanoparticles (WfAuNPs) in preventing microbial adhesion and enhanced wound healing potential on Wistar albino rats. The synthesized WfAuNPs were observed in the size range of 10–20 nm and used to develop 1% Carbopol® 934 based nano gold formulation (WfAuNPs-Carbopol®934). The WfAuNPs-Carbopol® nanoformulation was evaluated using viscosity and spreadability measurements. The in-vivo wound healing potential of WfAuNPs-Carbopol® 934 was evaluated on Wistar albino rats up to12 days and confirmed by percentage wound contraction, epithelialization period and histopathological studies. Further, the effect of WfAuNPs on microbial adhesion leading to biofilm formation was also evaluated against C. albicans and Cryptococcus neoformans. Results showed the effectiveness of WfAuNPs-Carbopol®934 nanoformulation in preventing microbial adhesion and in rapid aggregation of collagen fibrils, granular tissue formation and rejuvenation of epithelial lining, leading to quick healing and closures of wounds as compared to the standard marketed drug (5% Povidone iodine) and control. The Chapter 5 describes the therapeutic effectiveness of biogenically synthesized Woodfordia fruticosa nanoparticles (WfAuNPs) for the treatment of psoriasis. Heat shock proteins (HSPs) emerged as a therapeutic target and it was observed that inhibition of viii HSP70-1 plays a pivotal role in the management of psoriasis. In-silico investigation involving techniques like molecular docking and molecular dynamics (MD) simulation analysis was performed against HSP70-1. Further, anti-psoriatic activity of bioactive immunomodulatory compounds present in ethanolic extract of Woodfordia fruticosa flowers (Wffe) using combination of bioinformatics together with ethnopharmacological approach has been explored in this study. Myricetin (- 8.024), Quercetin (- 7.368) and Ellagic acid (- 7.311) were the top three compounds with minimum energy levels as well as high therapeutic value/ADMET as compared to currently available marketed anti-psoriatic drug Tretinoin (- 7.195). ADMET prediction was used to screen ligands for drug-likeness and efficacy. Further, biogenically Woodfordia fruticosa gold nanoparticles (WfAuNPs) were synthesized and characterized by UV-Visible Spectroscopy (UV-vis), Dynamic Light Scattering (DLS), Zeta Potential, X-Ray Diffraction (XRD) and High Resolution Transmission Electron Microscopy (HRTEM) techniques. Synthesized WfAuNPs observed in the size range of 10-20 nm and were used to develop WfAuNPs-Carbopol® 934 ointment gel. Subsequently, the therapeutic efficacy of WfAuNPs-Carbopol® 934 was checked against 5 % Imiquimod-induced psoriasis. WfAuNPs-Carbopol® 934 was found to be better therapeutic effect in reducing the mean DAI score (0.63 ± 0.08), IL-22 level (18.15 ± 0.30 pg/ml) along with reduced epidermal thickness, parakeratosis and marked decrease in the hyperproliferation of keratinocytes. Results of the study revealed that the WfAuNPs- Carbopol® 934 could be an effective alternative treatment for psoriasis in near future.