Spectrochimica Acta Part A 79 (2011) 594–598 Contents lists available at ScienceDirect Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa Biosynthesis of silver nanoparticles using citrus sinensis peel extract and its antibacterial activity S. Kaviya a,∗ , J. Santhanalakshmi a , B. Viswanathan b , J. Muthumary c , K. Srinivasan c a Department of Physical Chemistry, University of Madras, Guindy Campus, Chennai 600 025, India b National Center for Catalysis Research, Department of Chemistry, Indian Institute of Technology, Chennai 600 036, India c Department of Center for Advanced Study in Botany, University of Madras, Guindy Campus, Chennai 600 025, India article info Article history: Received 4 December 2010 Received in revised form 12 March 2011 Accepted 16 March 2011 Keywords: Biosynthesis Silver nanoparticles Citrus sinensis Antibacterial activity abstract Biosynthesis of silver nanoparticles (AgNPs) was achieved by a novel, simple green chemistry procedure using citrus sinensis peel extract as a reducing and a capping agent. The effect of temperature on the synthesis of silver nanoparticles was carried out at room temperature (25 ◦ C) and 60 ◦ C. The successful formation of silver nanoparticles has been confirmed by UV–vis, FTIR, XRD, EDAX, FESEM and TEM analysis and their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa (Gram-negative), and Staphylococcus aureus (Gram-positive) has been studied. The results suggest that the synthesized AgNPs act as an effective antibacterial agent. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Nanotechnology is emerging as a rapidly growing field with its application in science and technology [1]. Noble metal nanopar- ticles such as gold, silver and platinum are widely applied in medicinal applications. There is a growing need to develop an environmentally friendly process for the synthesis of nanoparti- cles that does not employ toxic chemicals. Generally, nanoparticles are prepared by a variety of chemical and physical methods [2–5], which are not environmentally friendly. Nowadays, green chem- istry procedures using various biological systems such as yeast, fungi, bacteria and plant extract [6–8] for the synthesis of nanopar- ticles are commonly used. Among them, plant extract based biosynthesis of metal nanoparticles especially silver and gold with controlled physicochemical properties have been reported by many researchers [9–11]. The recent reports include the biosynthesis using Murraya koenigii leaf [12], Mangosteen leaf [13], Mangifera indica leaf [14], Tansy fruit [15], Jatropha curcas [16], Cinnamomum Zeylanicum leaf [17], Camellia sinensis [18], Aloe vera [19], Mush- room [20], Honey [21] and so on. Silver nanoparticles prepared using biological materials have the properties of a high surface area, smaller in size and high dispersion. These prepared nanomateri- als have many applications, including spectrally selective coatings for solar energy absorption, generation of intercalation materials ∗ Corresponding author. Tel.: +91 9786665493. E-mail address: kaviyahere@gmail.com (S. Kaviya). for storage batteries, optical receptors [22], catalysis in chemical reactions, biolabelling, and antibacterial agents. It is well known, that silver is an effective antibacterial agent and possesses a strong antibacterial activity against bacteria, viruses and fungi, although the mechanism and the manner of action are still not well known [23]. The high antibacterial activity of silver nanoparticles is a result of well-developed surface, provid- ing maximum contact with the environment [24]. To apply silver nanoparticles in these applications, the control over the size and shape as well as the stability of silver nanoparticles is important. In the present study, biological synthesis was adopted since it is ecofriendly. A novel approach was made using citrus sinensis peel. Citrus species contain a wide range of active ingredients and research is still underway in finding uses for them as they are rich in vitamin C, flavonoids, acids and volatile oils [25–27]. In the present investigation, unreported green chemistry route for the synthesis of silver nanoparticles using extract derived from citrus sinensis peels and their antibacterial activity are described. 2. Materials and methods 2.1. Chemicals The citrus sinensis were collected from agricultural field located at Erode, India. All the chemicals were obtained from Aldrich. All the experiments were done in triplicates. Double distilled water was used for the experiments. 1386-1425/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.saa.2011.03.040