title: Cancer Cell Imaging Using in Situ Generated Gold Nanoclusters.
abstract: 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.
authors.affiliation: Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700 032, India.
authors.forename: Shyamtanu
authors.initials: S
authors.lastname: Chattoraj
authors.affiliation: Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700 032, India.
authors.forename: Md Asif
authors.initials: MA
authors.lastname: Amin
authors.affiliation: Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, 700 032, India.
authors.forename: Saswat
authors.initials: S
authors.lastname: Mohapatra
authors.affiliation: Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, 700 032, India. sghosh@iicb.res.in.
authors.forename: Surajit
authors.initials: S
authors.lastname: Ghosh
authors.affiliation: Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700 032, India. pckb@iacs.res.in.
authors.forename: Kankan
authors.initials: K
authors.lastname: Bhattacharyya
mesh_terms: D002460:Cell Line; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000633:toxicity; D005978:Glutathione / Q000378:metabolism; D006046:Gold / Q000737:chemistry*; D045325:HCT116 Cells; D006801:Humans; D007093:Imidazoles / Q000737:chemistry* / Q000633:toxicity; D061986:MCF-7 Cells; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000633:toxicity; D018613:Microscopy, Confocal; D013050:Spectrometry, Fluorescence
chemical_list: D005456:Fluorescent Dyes; D007093:Imidazoles; D006046:Gold; D005978:Glutathione
keywords: bio-imaging; cancer cells; glutathione; gold; nanoclusters