title: Enhanced Cellular Internalization: A Bactericidal Mechanism More Relative to Biogenic Nanoparticles than Chemical Counterparts.
abstract: Biogenic synthesis of silver nanoparticles for enhanced antimicrobial activity has gained a lot of momentum making it an urgent need to search for a suitable biocandidate which could be utilized for efficient capping and shaping of silver nanoparticles with enhanced bactericidal activity utilizing its secondary metabolites. Current work illustrates the enhancement of antimicrobial efficacy of silver nanoparticles by reducing and modifying their surface with antimicrobial metabolites of cell free filtrate of Trichoderma viride (MTCC 5661) in comparison to citrate stabilized silver nanoparticles. Nanoparticles were characterized by visual observations, UV-visible spectroscopy, zetasizer, and transmission electron microscopy (TEM). Synthesized particles were monodispersed, spherical in shape and 10-20 nm in size. Presence of metabolites on surface of biosynthesized silver nanoparticles was observed by gas chromatography-mass spectroscopy (GC-MS), energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The antimicrobial activity of both silver nanoparticles was tested against Shigella sonnei, Pseudomonas aeruginosa (Gram-negative) and Staphylococcus aureus (Gram-positive) by growth inhibition curve analysis and colony formation unit assay. Further, it was noted that internalization of biosynthesized nanoparticles inside the bacterial cell was much higher as compared to citrate stabilized particles which in turn lead to higher production of reactive oxygen species. Increase in oxidative stress caused severe damage to bacterial membrane enhancing further uptake of particles and revoking other pathways for bacterial disintegration resulting in complete and rapid death of pathogens as evidenced by fluorescein diacetate/propidium iodide dual staining and TEM. Thus, study reveals that biologically synthesized silver nanoarchitecture coated with antimicrobial metabolites of T. viride was more potent than their chemical counterpart in killing of pathogenic bacteria.
authors.affiliation: CSIR-National Botanical Research Institute , Rana Pratap Marg, Lucknow, 226 001, India.
authors.forename: Madhuree
authors.initials: M
authors.lastname: Kumari
authors.affiliation: CSIR-Indian Institute of Toxicology Research , Vishvigyan Bhawan 31, Mahatma Gandhi Marg, Lucknow, 226 001, India.
authors.forename: Shatrunajay
authors.initials: S
authors.lastname: Shukla
authors.affiliation: CSIR-National Botanical Research Institute , Rana Pratap Marg, Lucknow, 226 001, India.
authors.forename: Shipra
authors.initials: S
authors.lastname: Pandey
authors.affiliation: CSIR-National Botanical Research Institute , Rana Pratap Marg, Lucknow, 226 001, India.
authors.forename: Ved P
authors.initials: VP
authors.lastname: Giri
authors.affiliation: CSIR-National Botanical Research Institute , Rana Pratap Marg, Lucknow, 226 001, India.
authors.forename: Anil
authors.initials: A
authors.lastname: Bhatia
authors.affiliation: CSIR-National Botanical Research Institute , Rana Pratap Marg, Lucknow, 226 001, India.
authors.forename: Tusha
authors.initials: T
authors.lastname: Tripathi
authors.affiliation: CSIR-Indian Institute of Toxicology Research , Vishvigyan Bhawan 31, Mahatma Gandhi Marg, Lucknow, 226 001, India.
authors.forename: Poonam
authors.initials: P
authors.lastname: Kakkar
authors.affiliation: CSIR-National Botanical Research Institute , Rana Pratap Marg, Lucknow, 226 001, India.
authors.forename: Chandra S
authors.initials: CS
authors.lastname: Nautiyal
authors.affiliation: CSIR-National Botanical Research Institute , Rana Pratap Marg, Lucknow, 226 001, India.
authors.forename: Aradhana
authors.identifier: http://orcid.org/0000-0002-3288-2736
authors.initials: A
authors.lastname: Mishra
mesh_terms: D000900:Anti-Bacterial Agents; D053768:Metal Nanoparticles; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts; D011550:Pseudomonas aeruginosa; D012834:Silver; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D012834:Silver
keywords: Trichoderma viride; bacterial disintegration; bactericidal activity; green synthesis; nanoparticles characterization; silver nanoparticles