Please cite this article in press as: Muthukrishnan, S., et al., Biosynthesis, characterization and antibacterial effect of plant-mediated silver nanoparticles using Ceropegia thwaitesii – An endemic species. Ind. Crops Prod. (2014), http://dx.doi.org/10.1016/j.indcrop.2014.10.022 ARTICLE IN PRESS G Model INDCRO-7579; No. of Pages 6 Industrial Crops and Products xxx (2014) xxx–xxx Contents lists available at ScienceDirect Industrial Crops and Products jo ur nal home p age: www.elsevier.com/locate/indcrop Biosynthesis, characterization and antibacterial effect of plant-mediated silver nanoparticles using Ceropegia thwaitesii – An endemic species S. Muthukrishnan a , S. Bhakya b , T. Senthil Kumar c,∗ , M.V. Rao a a Department of Plant Science, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India b Department of Zoology, Rajah Serfoji Govt. College, Thanjavur 613 005, Tamil Nadu, India c Department of Industry University Collaboration, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India a r t i c l e i n f o Article history: Received 20 April 2014 Received in revised form 10 October 2014 Accepted 10 October 2014 Available online xxx Keywords: Ceropegia thwaitesii Green synthesis Silver nanoparticles X-ray diffraction Scanning electron microscopy (SEM) Human pathogens a b s t r a c t Leaf extract of in vitro raised plants of Ceropegia thwaitesii was assessed for the green synthesis of silver nanoparticles (AgNPs). The biosynthesized AgNPs were authorized by UV–vis spectrophotometer with surface plasmon resonance at 430 nm. The scanning electron microscope (SEM), dynamic light scattering (DLS) analysis confirmed the particle size 100 nm, and X-ray diffraction (XRD) confirmed the crystalline character of AgNPs. Further, Fourier transform infrared (FTIR) authorized the presence of triterpenoids and methoxy groups played an important reduction role in the synthesis process. It shows the significant antibacterial efficacy against Salmonella typhi, Shigella flexneri, Klbsiella pneumonia, Eschericia coli and others species. From the results, it is suggested that green synthesized AgNPs could be used effectively in future biomedical engineering. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Nanoparticles (NPs) are a group of materials with distinctive fea- tures and extensive applications in different fields of science and medicine (Matei et al., 2008). Moral metal nanoparticles have been extensively studied and different approaches have been engaged for the preparation of metal nanoparticles (Raveendran et al., 2003). Among them, silver nanoparticles (AgNPs) have much attention for their unique nature and advantage used on various experi- ments (Ghosh et al., 1996; Geddes et al., 2003). AgNPs released Ag + ions and they are interacting with the thiol groups in bacterial proteins and affect the DNA replication (Marini et al., 2007). Holt and Bard (2005) reported Ag + ions are uncouple the respiratory chain from oxidative phosphorylation and collapse the proton- motive force across the cytoplasmic membrane. AgNPs are the most fashionable functionalizing and commercializing nanoparticle due to their exclusive physicochemical properties such as electric, optical, catalytic and particularly antimicrobial properties (Tricoli and Pratsinis, 2010; Chen et al., 2011). The nanoparticles showed ∗ Corresponding author. Tel.: +91 4312407071 Ext. 130; fax: +91 4312407045. E-mail addresses: muthukrishnan1985@gmail.com (S. Muthukrishnan), senthil2551964@yahoo.co.in (T. Senthil Kumar). potential anti-bacterial activity and significantly higher synergistic effect with many antibiotics (Devi and Joshi, 2012). The interactions of AgNPs with bacteria are dependent on the size and structure of the nanoparticles (Panᡠcek et al., 2006; Pal et al., 2007). AgNPs as antibacterial agents are now used extensively different fields of medical such as molecular imaging, diagnosis and treatment of car- diovascular diseases and drug delivery (Kohl et al., 2011; Dar et al., 2013; El-Rafie et al., 2012). Nanoparticle synthesis is currently a significant area of research, searching for an eco-friendly approach and green materials for current scenario. Number of AgNPs has been developed by a phys- ical, chemical approach and recently developed biological method (Dipankar and Murugan, 2012). Latter it has emerged as a green alternative, because of its cost-effective, eco-friendly and easily scaled-up nature. It has great potential with natural reductants (Sivalingam et al., 2012) such as bacteria, fungus and plants extracts (Niraimathi et al., 2013; Kalimuthu et al., 2008; Ingle et al., 2008). Ceropegia species are store house of various and valuable phyto-constituents that are routinely used in traditional Indian ayurvedic drugs for the treatment of gastric disorders, diarrhoea, dysentery, urinary tract disorders, etc. (Kirtikar and Basu, 1935). The medicinally importance of the genus Ceropegia is mainly due to the presence of a pyridine alkaloid called ‘Cerpegin’ (Sukumar et al., 1995). It has various biological features, including http://dx.doi.org/10.1016/j.indcrop.2014.10.022 0926-6690/© 2014 Elsevier B.V. All rights reserved.