Microwave Accelerated Green Synthesis of Stable Silver Nanoparticles with Eucalyptus globulus Leaf Extract and Their Antibacterial and Antibiofilm Activity on Clinical Isolates.

Khursheed Ali,Quaiser Saquib,Sourabh Dwivedi,Javed Musarrat,Abdulaziz A Al-Khedhairy,Bilal Ahmed,Vipul Bansal

doi:10.1371/journal.pone.0131178

Khursheed Ali, Quaiser Saquib + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0131178

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Journal: PloS one	Publication Date: Jul 1, 2015
Citations: 180	License type: CC BY 4.0

Affiliation: King Saud University, Aligarh Muslim University

Abstract

A simple and rapid microwave assisted method of green synthesis of silver nanoparticles (AgNPs) was developed using aqueous leaf extract of Eucalyptus globulus(ELE), and their antibacterial and antibiofilm potential investigated. With this aim, the aqueous solutions of ELE and AgNO3(1 mM) were mixed (1:4 v/v), and microwave irradiated at 2450 Mhz, for 30 sec. The instant color change of the ELE-AgNO3 mixture from pale yellow to dark brown indicated ELE-AgNPs synthesis. The intensity of peak at 428 nm in UV-Vis spectra, due to the surface plasmon resonance of AgNPs, varied with the amount of ELE, AgNO3 concentration, pH and time of incubation. The biosynthesized ELE-AgNPs were characterized by UV-visible spectroscopy, XRD, TEM, SEM-EDX, FTIR and TGA analyses. The size of ELE-AgNPs was determined to be in range of 1.9–4.3 nm and 5-25 nm, with and without microwave treatment, respectively. SEM exhibited the capping of AgNPs with the ELE constituents, and validated by FTIR analysis. The FTIR data revealed the presence of plant organic constituents and metabolites bound to ELE-AgNPs, which contributes for their stability. The antimicrobial activity of ELE-AgNPs was assessed by growth and biofilm inhibition of extended spectrum β-lactamase (ESBL) producing Pseudomonas aeruginosa, Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) clinical bacterial isolates. The results demonstrated that S. aureus were more sensitive to ELE-AgNPs than E. coli and P. aeruginosa. MRSA exhibited higher sensitive than MSSA, whereas P. aeruginosa were more sensitive than E. coli to ELE-AgNPs treatment. Also, significant (83 ± 3% and 84 ± 5%) biofilm inhibition was observed in case of S. aureus and P. aeruginosa, respectively. The results elucidated environmentally friendly, economical and quick method for production of colloidal bio-functionalized ELE-AgNPs, for effectual clinical applications, as broad spectrum antibacterial agents and biofilm inhibitors.

Highlights

The phytochemicals present in plant extracts have been reported to cause reduction of metal ions to nanoparticles (NPs) and, eventually obliterate the use of toxic chemicals, high pressure, temperature, energy and maintenance of microbial cultures [1,2]
The bacterial isolates including E. coli-157, Pseudomonas aeruginosa620 (Extended-Spectrum β-Lactamases), Methicillin-resistant Staphylococcus aureus MR-6 (MRSA) and Methicillin-sensitive Staphylococcus aureus (MSSA) MS-6, and ESBL negative E. coli-255 and Pseudomonas aeruginosa-222 were obtained from the culture stocks of the Department of Microbiology, Jawaharlal Nehru Medical College, Aligarh Muslim University (AMU), Aligarh, India, and revalidated in our laboratory
The scheme-I shows that the aqueous solutions of Eucalyptus globulus extract (ELE) and AgNO3 when mixed in a ratio of 1:4, exhibited a gradual change in color from pale yellow to dark brown after 3 h at 37°C

Summary

Introduction

The phytochemicals present in plant extracts have been reported to cause reduction of metal ions to nanoparticles (NPs) and, eventually obliterate the use of toxic chemicals, high pressure, temperature, energy and maintenance of microbial cultures [1,2]. Followed by 30 min incubation at ambient temperature, resulted in instant change in color of the ELE-AgNO3 reaction mixture to dark brown, which is regarded as a preliminary indication of AgNPs synthesis.

Results

Conclusion