Cytotoxicity and fluorescence studies of silica-coated CdSe quantum dots for bioimaging applications
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The toxicological effects of silica-coated CdSe quantum dots (QDs) were investigated systematically on human cervical cancer cell line. Trioctylphosphine oxide capped CdSe QDs were synthesized and rendered water soluble by overcoating with silica, using aminopropyl silane as silica precursor. The cytotoxicity studies were conducted by exposing cells to freshly synthesized QDs as a function of time (0–72 h) and concentration up to micromolar level by Lactate dehydrogenase assay, MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide] assay, Neutral red cell viability assay, Trypan blue dye exclusion method and morphological examination of cells using phase contrast microscope. The in vitro analysis results showed that the silica-coated CdSe QDs were nontoxic even at higher loadings. Subsequently the in vivo fluorescence was also demonstrated by intravenous administration of the QDs in Swiss albino mice. The fluorescence images in the cryosections of tissues depicted strong luminescence property of silica-coated QDs under biological conditions. These results confirmed the role of these luminescent materials in biological labeling and imaging applications.
KeywordsQuantum dots Cytotoxicity Semiconductors Luminescence Silica-coating Health safety EHS
We gratefully acknowledge Department of Biotechnology, Ministry of Science and Technology, Govt. of India, New Delhi, for the financial assistance as research grant (Order No.BT/PR9904/NNT/28/63/2007) given to Dr. Annie Abraham, Principal Investigator, DBT project; Dr. K. George Thomas, Scientist, National Institute of Interdisciplinary Science and Technology (CSIR), Trivandrum, India for supplying nanomaterials; UGC, Govt. of India for the research fellowship to Vinayakan R; Dr. Jamuna, Institute of English, University of Kerala, India for proof reading.
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