Preparation of multi-coloured different sized fluorescent gold clusters from blue to NIR, structural analysis of the blue emitting Au7cluster, and cell-imaging by the NIR gold cluster

Spectroscopy, Near-Infrared Cell Survival Ultraviolet Rays 02 engineering and technology Hydrogen-Ion Concentration Glutathione Microscopy, Fluorescence Cell Line, Tumor Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization Humans Quantum Theory Spectrophotometry, Ultraviolet Gold 0210 nano-technology
DOI: 10.1039/c4nr04338c Publication Date: 2014-11-28T17:36:24Z
ABSTRACT
Blue, green, orange-red, red and NIR emitting gold quantum clusters have been prepared in aqueous media by using a bioactive peptide glutathione (reduced) at physiological pH. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) analyses show that the core structure sizes of the five different gold clusters are Au7 (blue), Au16 (green), Au19 (orange-red), Au21 (red) and Au22 (NIR). The photo-stability and pH-stability of these quantum clusters have been measured, and these are photo-stable against continuous UV irradiation for a few hours. They also exhibit moderate to good pH-stability within the pH range of 5-12.5. A computational study reveals the organisation of gold atoms in the thiolate-protected blue quantum cluster and its several structural parameters, including the mode of interaction of ligand molecules with Au atoms in the Au7 cluster. Interestingly, it has been found that NIR emitting gold quantum cluster can easily be internalized into the adenocarcinomic human alveolar basal epithelial cell line (A549 cell line). Moreover, a MTT assay indicates that our NIR emitting gold quantum cluster show very low cytotoxicy to A549 cancer cells.
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