Sun light mediated synthesis of gold nanoparticles as carrier for 6-mercaptopurine: Preparation, characterization and toxicity studies in zebrafish embryo model Moorthy Ganeshkumar a , Thotapalli Parvathaleswara Sastry b , Muniram Sathish Kumar c , Murugan Girija Dinesh d , Sudalyandi Kannappan e , Lonchin Suguna a, * a Department of Biochemistry, Central Leather Research Institute, Council of Scientific and Industrial Research, Chennai 600020, India b Bioproducts Laboratory, Central Leather Research Institute, Chennai 600020, India c Department of Pharmaceutics, Anna University, Trichy, Tamilnadu, India d Thanthai Hansroever College, Perambalur, Tamilnadu, India e Central Institute of Brackish Water Aquaculture, Chennai 600028, India 1. Introduction Nanotechnology mainly deals with the synthesis of nanopar- ticles of variable size, shape, surface charge and narrow size distribution. Nanoparticles are effectively synthesized by various chemical and physical methods which are quite expensive and the chemicals used for reduction and stabilization of the metal nanoparticles are potentially hazardous to the environment. To triumph over these problems, gold nanoparticles synthesis using green chemistry is one of the emerging areas in the recent past [1,2]. Gold nanoparticles have been successfully synthesized using numerous plant extracts like lemongrass [3], Cinnamommum camphora [4], neem [5], Aloe vera [6] and coriander leaf [7]. More recently, an economic and convenient method for the preparation of metal nanoparticles from metal ions is explained by Luo [8]. Gold nanoparticles (AuNPs) are being employed in many different bio-applications like cell labeling, cell imaging, enhanced magnetic resonance imaging, optical biosensors, electrochemical biosensor and drug delivery [9]. Recently, gold nanoparticles prepared using gum arabic has been used to reduce and stabilize AuNPs for X-ray contrast imaging study [10]. AuNPs are also used as a carrier for insulin for the treatment of diabetes [11]. Biopolymers are one of the most attractive options for surface coating as they contain various functional groups like carboxy, amino, thio and hydroxyl units on their backbone. These biopolymers when coated on gold nanoparticles facilitate conju- gation with drug molecules, fluorescent dyes and show biocom- patibility and colloidal stability in various buffers at physiological conditions [12]. Though AuNPs have various biomedical applications; prior to clinical application, they should be tested for their potential toxicity and health impact. In this work, we describe an eco- friendly method for the preparation of biocompatible AuNPs by exposing a nutrient agar–HAuCl 4 aqueous solution mixture to sunlight. In this process, sunlight acts as the radiation energy and nutrient agar acts both as a reducing agent and as a surface coating material for AuNPs. To check the toxicity of the prepared AuNPs, both in vitro cell culture model and in vivo animal model are being used. In this study, we have used zebrafish embryo as a model to evaluate the Materials Research Bulletin 47 (2012) 2113–2119 A R T I C L E I N F O Article history: Received 8 November 2011 Received in revised form 16 May 2012 Accepted 11 June 2012 Available online 19 June 2012 Keywords: A. Inorganic compounds A. Nanostructures A. Metals C. Electron microscopy C. Infrared spectroscopy A B S T R A C T The objective of this study is to synthesize green chemistry based gold nanoparticles by sun light irradiation method. The prepared gold nanoparticles (AuNPs) were modified using folic acid and then coupled with 6-mercaptopurine. These modified nanoparticles were used as a tool for targeted drug delivery to treat laryngeal cancer. In the present study, novel bionanocomposites containing nutrient agar coated gold nano particles (N-AuNPs) coupled with 6-mercaptopurine (drug) (N-AuNPs-Mp), folic acid (ligand) (N-AuNPs-Mp-Fa) and rhodamine (dye) (N-AuNPs-Rd), a fluorescent agent, were prepared and characterized by IR, UV, TEM, Particle size analysis and in vitro stability. The toxicity and fluorescence of N-Au was studied using zebrafish embryo model. The in vitro cytotoxicity of free Mp, N- Au-Mp and N-Au-Mp-Fa against HEp-2 cells was compared and found that the amount of Mp required to achieve 50% of growth of inhibition (IC 50 ) was much lower in N-Au-Mp-Fa than in free Mp and N-Au-Mp. ß 2012 Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: +91 44 24911386x7149; fax: +91 44 24911589. E-mail address: slonchin@yahoo.co.uk (L. Suguna). Contents lists available at SciVerse ScienceDirect Materials Research Bulletin jo u rn al h om ep age: ww w.els evier.c o m/lo c ate/mat res b u 0025-5408/$ – see front matter ß 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.materresbull.2012.06.015