Phyto-Synthesis, Characterization and Biological Applications of Gold Nanoparticles (AuNPs) Using Toxicosis Mediated Plant Nicotiana glauca Graham

Nanotechnology is a newer branch of material science that thrives in the interdisciplinary fields including biomedical, therapeutics, diagnostics etc. Among the metallic nanoparticles, gold nanoparticles (AuNPs) in particular are known for their versatile biological applications in several scientific fields in general and specifically the biomedical field. The current article accounts for an environmentally safe method for AuNPs synthesis using the chloroauric acid and ethanolic leaf extract of Nicotiana glauca (NG), for the first time. Various analytical techniques identified properties of synthesized AuNP to include UV-Vis absorption spectroscopy, Fourier-Transform Infrared Radiation (FT-IR), and scanning electron microscopy (SEM) for surface morphology. The average diameter of synthesized AuNP was about 100 nm. Antimicrobial activity of AuNPs was investigated on Gram-positive (Staphylococcus aureus), Gram-negative (Escherichia coli, Proteus mirabilis, and Shigella flexneri) and fungi (Candida albicans) using well diffusion method. Cytotoxic action on Hela/HepG2 tumor cell lines and normal rat splenic cells were tested through cell viability. Furthermore, Larvicidal toxicity was performed on 4th instar larvae of Culex pipens. NG extract (NGEx) alone exerted significantly lower (6-7 mm) antimicrobial activity than that of NG extract with AuNPs (14-15 mm). Cytotoxicity screening revealed that both preparations were growth inhibitory on both cell lines and splenic cells. For larvicidal properties, the extract and gold nanoparticles (NGExAu) showed larvicidal effect against 4th instar larvae of Culex pipiens. NGExAu was more lethal (LC50 = 164.4072 ppm; LC90 = 613.366 ppm) against Cx. pipiens under exposure for 24 h with lesser lethal content compared to NGEx of only (LC50 = 752.865 ppm; LC90 = 4455.726 ppm).