title: Specific Reagent for Cr(III): Imaging Cellular Uptake of Cr(III) in Hct116 Cells and Theoretical Rationalization.
abstract: A new rhodamine-based reagent (L1), trapped inside the micellar structure of biologically benign Triton-X 100, could be used for specific recognition of Cr(III) in aqueous buffer medium having physiological pH. This visible light excitable reagent on selective binding to Cr(III) resulted in a strong fluorescence turn-on response with a maximum at ∼583 nm and tail of that luminescence band extended until 650 nm, an optical response that is desired for avoiding the cellular autofluorescence. Interference studies confirm that other metal ions do not interfere with the detection process of Cr(III) in aqueous buffer medium having pH 7.2. To examine the nature of binding of Cr(III) to L1, various spectroscopic studies are performed with the model reagent L2, which tend to support Cr(III)-η(2)-olefin π-interactions involving two olefin bonds in molecular probe L1. Computational studies are also performed with another model reagent LM to examine the possibility of such Cr(III)-η(2)-olefin π-interactions. Presumably, polar functional groups of the model reagent LM upon coordination to the Cr(III) center effectively reduce the formal charge on the metal ion and this is further substantiated by results of the theoretical studies. This assembly is found to be cell membrane permeable and shows insignificant toxicity toward live colon cancer cells (Hct116). Confocal laser scanning microscopic studies further revealed that the reagent L1 could be used as an imaging reagent for detection of cellular uptake of Cr(III) in pure aqueous buffer medium by Hct116 cells. Examples of a specific reagent for paramagnetic Cr(III) with luminescence ON response are scanty in the contemporary literature. This ligand design helped us in achieving the turn on response by utilizing the conversion from spirolactam to an acyclic xanthene form on coordination to Cr(III).
authors.affiliation: Organic Chemistry Division, CSIR-National Chemical Laboratory , Pune, Maharashtra 411008, India.
authors.forename: Firoj
authors.initials: F
authors.lastname: Ali
authors.affiliation: Analytical Science and Centralized Instrument Facility, CSIR-Central Salt & Marine Chemicals Research Institute , Bhavnagar, Gujarat 364002, India.
authors.forename: Sukdeb
authors.initials: S
authors.lastname: Saha
authors.affiliation: Organic Chemistry Division, CSIR-National Chemical Laboratory , Pune, Maharashtra 411008, India.
authors.forename: Arunava
authors.initials: A
authors.lastname: Maity
authors.affiliation: Chromatin and Disease Biology Lab, National Centre for Cell Science , Pune 411007, India.
authors.forename: Nandaraj
authors.initials: N
authors.lastname: Taye
authors.affiliation: Analytical Science and Centralized Instrument Facility, CSIR-Central Salt & Marine Chemicals Research Institute , Bhavnagar, Gujarat 364002, India.
authors.forename: Mrinal Kanti
authors.initials: MK
authors.lastname: Si
authors.affiliation: Analytical Science and Centralized Instrument Facility, CSIR-Central Salt & Marine Chemicals Research Institute , Bhavnagar, Gujarat 364002, India.
authors.forename: E
authors.initials: E
authors.lastname: Suresh
authors.affiliation: Analytical Science and Centralized Instrument Facility, CSIR-Central Salt & Marine Chemicals Research Institute , Bhavnagar, Gujarat 364002, India.
authors.forename: Bishwajit
authors.initials: B
authors.lastname: Ganguly
authors.affiliation: Chromatin and Disease Biology Lab, National Centre for Cell Science , Pune 411007, India.
authors.forename: Samit
authors.initials: S
authors.lastname: Chattopadhyay
authors.affiliation: Organic Chemistry Division, CSIR-National Chemical Laboratory , Pune, Maharashtra 411008, India.
authors.forename: Amitava
authors.initials: A
authors.lastname: Das
mesh_terms: D002460:Cell Line; D002857:Chromium / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D021241:Spectrometry, Mass, Electrospray Ionization; D013055:Spectrophotometry, Infrared
chemical_list: D002857:Chromium