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Open Access Nano Express

Green synthesis of silk sericin-capped silver nanoparticles and their potent anti-bacterial activity

Pornanong Aramwit1*, Nipaporn Bang1, Juthamas Ratanavaraporn2 and Sanong Ekgasit3

Author Affiliations

1 Bioactive Resources for Innovative Clinical Applications Research Unit and Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Chulalongkorn University, 254 PhyaThai Road, Patumwan, Bangkok 10330, Thailand

2 Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, 254 PhyaThai Road, Patumwan, Bangkok 10330, Thailand

3 Sensor Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, 254 PhyaThai Road, Patumwan, Bangkok 10330, Thailand

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Nanoscale Research Letters 2014, 9:79  doi:10.1186/1556-276X-9-79

Published: 17 February 2014

Abstract

In this study, a ‘green chemistry’ approach was introduced to synthesize silk sericin (SS)-capped silver nanoparticles (AgNPs) under an alkaline condition (pH 11) using SS as a reducing and stabilizing agent instead of toxic chemicals. The SS-capped AgNPs were successfully synthesized at various concentrations of SS and AgNO3, but the yields were different. A higher yield of SS-capped AgNPs was obtained when the concentrations of SS and AgNO3 were increased. The SS-capped AgNPs showed a round shape and uniform size with diameter at around 48 to 117 nm. The Fourier transform infrared (FT-IR) spectroscopy result proved that the carboxylate groups obtained from alkaline degradation of SS would be a reducing agent for the generation of AgNPs while COO and NH2+ groups stabilized the AgNPs and prevented their precipitation or aggregation. Furthermore, the SS-capped AgNPs showed potent anti-bacterial activity against various gram-positive bacteria (minimal inhibitory concentration (MIC) 0.008 mM) and gram-negative bacteria (MIC ranging from 0.001 to 0.004 mM). Therefore, the SS-capped AgNPs would be a safe candidate for anti-bacterial applications.

Keywords:
Green synthesis; Silver nanoparticle; Silk sericin; Alkaline degradation; Anti-bacterial activity