Plant-Extract-Assisted Green Synthesis of Silver Nanoparticles Using Origanum vulgare L. Extract and Their Microbicidal Activities

Mohammed Shaik,Adeem Mahmood,Anis Ahamed,Mufsir Kuniyil,Mohammed Siddiqui,Merajuddin Khan,Mujeeb Khan,Syed Adil,Hamad Alkhathlan,Abdulrahman Al-Warthan,Jilani Shaik

doi:10.3390/su10040913

Abstract

Plant-mediated green synthesis of nanomaterials has been increasingly gaining popularity due to its eco-friendly nature and cost-effectiveness. In the present study, we synthesized silver nanoparticles (AgNPs) by using an aqueous solution of Saudi Origanum vulgare L. plant extract as a bioreducing agent. The as-synthesized AgNPs were characterized using various microscopic and spectroscopic techniques. The results indicated the formation of crystalline face-centered cubic (fcc) AgNPs. Additionally, FT-IR study confirmed that the O. vulgare L. extract not only functioned as a bioreductant but also stabilized the surface of the AgNPs by acting as a capping agent. Moreover, the effect of the amount of the plant extract on the size and the antimicrobial activity of the NPs was also assessed. It was found that with increasing amounts of plant extract, the size of the NPs was decreased. Moreover, as-synthesized AgNPs as well as O. vulgare L. plant extract were separately tested to examine their antimicrobial activities. The activities were tested against various bacterial and fungal microorganisms including Shigella sonnei, Micrococcus luteus, Escherichia coli, Aspergillus flavus, Alternaria alternate, Paecilomyces variotii, Phialophora alba, and so on. These results evidently show that the inclusion of O. vulgare L. extracts improves the solubility of AgNPs, which led to a significant enhancement in the toxicity of the NPs against the assessed microorganisms.

Highlights

Due to their extraordinary physicochemical properties, metallic nanoparticles (NPs) have been effectively applied in numerous fields, including health care, synthetic biology, and cellular transportation [1]
The ecofriendly synthesis of AgNPs was performed under a reflux environment using Saudi O. vulgare L. extract
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Summary

Introduction

Due to their extraordinary physicochemical properties, metallic nanoparticles (NPs) have been effectively applied in numerous fields, including health care, synthetic biology, and cellular transportation [1]. Due to the dual nature of the phytomolecules, PE-based synthesis qualifies as a best methodology for preparing AgNPs for various biological applications, since the resultant NPs can be directly applied without any Sustainability 2018, 10, 913 post treatment [44] These types of reactions can be performed without using any sophisticated laboratory facilities and minimize the use of hazardous chemicals and stabilizers [45]. The NPs obtained from green methods can be more effective for biological applications when compared with those from chemical methods, and the green methods can be possibly exploited for large-scale synthesis of AgNPs [46] It is well established in the literature that the percentage composition of individual constituents of the different parts of the same plants may vary significantly [47]. The potential antimicrobial properties of the as-synthesized AgNPs were evaluated against various bacterial and fungal strains, such as Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27584), Salmonella typhimurium (ATCC 14028), Staphylococcus aureus (ATCC 29213), Staphylococcus epidermidis (MTCC 3615), Shigella sonnei (ATCC 11060), Methicillin-resistant Staphylococcus aureus (MRSA) (ATCC 12498), Micrococcus luteus (ATCC 4698), Aspergillus flavus (ATCC 9643), Alternaria alternate (ATCC 13963), Paecilomyces variotii (ATCC 3630), and Phialophora alba (ATCC 9625)

UV–Vis Spectral Analysis

Materials

Microbicidal Activity

Characterization

Conclusions and Future Implications