Sunlight-induced rapid and efficient biogenic synthesis of silver nanoparticles using aqueous leaf extract of Ocimum sanctum Linn. with enhanced antibacterial activity.

Goutam Brahmachari,Shyamal K Jash,Bubun Banerjee,Narayan C Mandal,Soma Barman,Sajal Sarkar,Rajiv Roy,Ranjan Ghosh

doi:10.1186/s13588-014-0018-6

Goutam Brahmachari, Shyamal K Jash + Show 6 more

Open Access

https://doi.org/10.1186/s13588-014-0018-6

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Abstract

BackgroundNanotechnology is now regarded as a distinct field of research in modern science and technology with multifaceted areas including biomedical applications. Among the various approaches currently available for the generation of metallic nanoparticles, biogenic synthesis is of increasing demand for the purpose of green nanotechnology. Among various natural sources, plant materials are the most readily available template-directing matrix offering cost-effectiveness, eco-friendliness, and easy handling. Moreover, the inherent pharmacological potentials of these medicinal plant extracts offer added biomedical implementations of the synthesized metal nanoparticles.ResultsA robust practical method for eco-friendly synthesis of silver nanoparticles using aqueous leaf extract of Ocimum sanctum (Tulsi) as both reducing and capping agent, under the influence of direct sunlight has been developed without applying any other chemical additives. The nanoparticles were characterized with the help of UV-visible spectrophotometer and transmission electron microscopy (TEM). The prepared silver nanoparticles exhibited considerable antibacterial activity. The effects were more pronounced on non-endospore-forming Gram-positive bacteria viz., Staphylococcus aureus, Staphylococcus epidermidis, and Listeria monocytogenes than endospore-forming species Bacillus subtilis. The nanoparticles also showed prominent activity on Gram-negative human pathogenic Salmonella typhimurium, Escherichia coli, Pseudomonas aeruginosa, and plant pathogenic Pantoea ananatis. A bactericidal mode of action was observed for both Gram-positive and Gram-negative bacteria by the nanoparticles.ConclusionsWe have developed a very simple, efficient, and practical method for the synthesis of silver nanoparticles using aqueous leaf extract of O. sanctum under the influence of direct sunlight. The biosynthesis of silver nanoparticles making use of such a traditionally important medicinal plant without applying any other chemical additives, thus offers a cost-effective and environmentally benign route for their large-scale commercial production. The nanoparticles dispersed in the mother solution showed promising antibacterial efficacy.Graphical Sunlight-induced rapid and efficient biogenic synthesis of silver nanoparticles using aqueous leaf extract of Ocimum sanctum Linn. with enhanced antibacterial activity.Electronic supplementary materialThe online version of this article (doi:10.1186/s13588-014-0018-6) contains supplementary material, which is available to authorized users.

Highlights

Nanotechnology is regarded as a distinct field of research in modern science and technology with multifaceted areas including biomedical applications
Bioproduction of AgNPs was studied with different concentrations (3%, 5%, 7%, and 10%) of aqueous leaf extract of O. sanctum with 10−3 M AgNO3 solution
UV-visible spectra (Figure 2) indicated the formation AgNPs using these different concentrations of plant leaf extracts on exposure to direct sunlight for a time span of 60 min, and 7% plant leaf extract yielded the best result exhibiting the highest absorption band at 430 nm as a result of surface plasmon resonance (SPR) of silver nanoparticles

Summary

Introduction

Nanotechnology is regarded as a distinct field of research in modern science and technology with multifaceted areas including biomedical applications. Useful application of nanotechnology in medicinal purposes is currently one of the most fascinating areas of research. When cells or tissues get exposed to AgNPs, the active surface area of the nanoparticles become significantly large compared to that of the ordinary silver compounds. Such enhanced surface area of metallic nanoparticles is supposed to be responsible for exhibiting remarkably unusual physicochemical properties and biological activities [17]. Silverembedded fabrics are used in textile industry in manufacturing sporting equipments [18]

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