Chattoraj Shyamtanu, Amin Md Asif, Mohapatra Saswat, Ghosh Surajit, Bhattacharyya Kankan
Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700 032, India.
Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, 700 032, India.
Chemphyschem. 2016 Jan 4;17(1):61-8. doi: 10.1002/cphc.201500731. Epub 2015 Oct 23.
In situ generated fluorescent gold nanoclusters (Au-NCs) are used for bio-imaging of three human cancer cells, namely, lung (A549), breast (MCF7), and colon (HCT116), by confocal microscopy. The amount of Au-NCs in non-cancer cells (WI38 and MCF10A) is 20-40 times less than those in the corresponding cancer cells. The presence of a larger amount of glutathione (GSH) capped Au-NCs in the cancer cell is ascribed to a higher glutathione level in cancer cells. The Au-NCs exhibit fluorescence maxima at 490-530 nm inside the cancer cells. The fluorescence maxima and matrix-assisted laser desorption ionization (MALDI) mass spectrometry suggest that the fluorescent Au-NCs consist of GSH capped clusters with a core structure (Au8-13). Time-resolved confocal microscopy indicates a nanosecond (1-3 ns) lifetime of the Au-NCs inside the cells. This rules out the formation of aggregated Au-thiolate complexes, which typically exhibit microsecond (≈1000 ns) lifetimes. Fluorescence correlation spectroscopy (FCS) in live cells indicates that the size of the Au-NCs is ≈1-2 nm. For in situ generation, we used a conjugate consisting of a room-temperature ionic liquid (RTIL, [pmim][Br]) and HAuCl4. Cytotoxicity studies indicate that the conjugate, [pmim][AuCl4], is non-toxic for both cancer and non-cancer cells.
原位生成的荧光金纳米簇（Au-NCs）通过共聚焦显微镜用于对三种人类癌细胞进行生物成像，这三种癌细胞分别是肺癌细胞（A549）、乳腺癌细胞（MCF7）和结肠癌细胞（HCT116）。非癌细胞（WI38和MCF10A）中Au-NCs的含量比相应癌细胞中的含量少20 - 40倍。癌细胞中大量存在的谷胱甘肽（GSH）封端的Au-NCs归因于癌细胞中较高的谷胱甘肽水平。Au-NCs在癌细胞内部的荧光最大值在490 - 530 nm处。荧光最大值和基质辅助激光解吸电离（MALDI）质谱表明，荧光Au-NCs由具有核心结构（Au8 - 13）的GSH封端簇组成。时间分辨共聚焦显微镜表明细胞内Au-NCs的寿命为纳秒级（1 - 3 ns）。这排除了形成聚集的金硫醇配合物的可能性，聚集的金硫醇配合物通常具有微秒级（≈1000 ns）的寿命。活细胞中的荧光相关光谱（FCS）表明Au-NCs的尺寸约为1 - 2 nm。对于原位生成，我们使用了由室温离子液体（RTIL，[pmim][Br]）和HAuCl4组成的共轭物。细胞毒性研究表明，共轭物[pmim][AuCl4]对癌细胞和非癌细胞均无毒。
