Optical and cytotoxicity properties of water soluble type II CdTe/CdSe nanoparticles synthesised via a green method
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Optical and cytotoxicity properties of water soluble type II CdTe/CdSe nanoparticles synthesised via a green method Ncapayi Vuyelwa, Samuel. O. Oluwafemi, Sandile .P. Songca and Tetsuya. Kodama Vuyelwa Ncapayi1, Samuel. O. Oluwafemi2,3*, Sandile .P. Songca4 and Tetsuya. Kodama5 1
Department of Chemistry, Cape Peninsula University of Technology, P.O. Box 652, Cape Town, 8000, South Africa. 2 Department of Applied Chemistry, University of Johannesburg, P.O. Box 17011, Doornfontein 2028, Johannesburg, South Africa. 3 Centre for Nanomaterials Science Research, University of Johannesburg, Johannesburg, South Africa. 4 Department of Chemistry and Chemical Technology, Walter Sisulu University Mthatha campus, Private Bag XI, Mthatha, 5117, Eastern Cape, South Africa. 5 Graduate School of biomedical engineering, Tohoku University, 4-1 Seiryo, Aoba Sendai, Japan, 980-8575. ABSTRACT We herein report the optical and cytotoxicity properties of highly luminescent water soluble mercaptopropanoic acid (MPA) capped CdTe/CdSe core shell nanoparticles (NPs). The synthesis of the CdTe/CdSe NPs was carried out via a simple, one pot and economical route, involving the use of greener materials under ambient environment in the absence of an inert atmosphere. The temporal evolution of the size and optical properties of the nanomaterials was investigated by varying the reaction time and stability of the as-synthesised material at pH 12. The as-synthesised nanomaterials were characterised using UV-vis absorption and photoluminescence (PL) spectroscopy. The nanoparticles obtained were of high quality with high absorption and emission features. Addition of Se precursor to produce CdSe layer on the CdTe NPs core surface resulted in significant red shirt of both the absorption and emission maxima. The stability study showed that the emission maximum peak positions and FWHM remain the same with increase in emission intensity for all the NPs during the aging period. The cytotoxicity assay showed very high cell viability for the CdTe/CdSe NPs produced at 7 h compared with those produced at 30 mins as the concentration increased from 0.1 to 60 ug/ml. The lower cytotoxicity at the higher reaction time was attributed to the higher stability of the material and hence lower release of Cd2+.
INTRODUCTION Semiconductor nanoparticles (NPs) also known quantum dots (QDs) has emerged as potential and excellent materials for fluorescence imaging compared to traditional dyes. This has been attributed to their unique optical and electrical properties, good-photo and chemical stability which are unavailable in conventional fluorophores [1-4]. The size dependent properties of quantum dots (QDs) render them useful in many applications such as lasers, electronic devices, biological fluorescent labelling, to mention a few hence, tremendous effort has been devoted to their synthesis. Many synthetic methods have been reported in order to obtain high quality QDs and these can be broadly divided into two approaches namely, aqueous and organic approaches [3-8]. Nanoparti
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