title: Effect of metal oxidation state on FRET: a Cu(I) silent but selectively Cu(II) responsive fluorescent reporter and its bioimaging applications.
abstract: Copper(II) and copper(I) complexes of a newly designed and crystallographically characterized Schiff base (HL) derived from rhodamine hydrazide and cinnamaldehyde were isolated in pure form formulated as [Cu(L)(NO3)] (L-Cu) (1) and [Cu(HL)(CH3CN)(H2O)]ClO4 (HL-Cu) (2), and characterized by physicochemical and spectroscopic tools. Interestingly, complex 1 but not 2 offers red fluorescence in solution state, and eventually HL behaves as a Cu(II) ions selective FRET based fluorosensor in HEPES buffer (1 mM, acetonitrile-water: 1/5, v/v) at 25 °C at biological pH with almost no interference of other competitive ions. The dependency of the FRET process on the +2 oxidation state of copper has been nicely supported by exhaustive experimental studies comprising electronic, fluorimetric, NMR titration, and theoretical calculations. The sensing ability of HL has been evaluated by the LOD value towards Cu(II) ions (83.7 nM) and short responsive time (5-10 s). Even the discrimination of copper(I) and copper(II) has also been done using only UV-Vis spectroscopic study. The efficacy of this bio-friendly probe has been determined by employing HL to detect the intercellular distribution of Cu(II) ions in HeLa cells by developing image under fluorescence microscope.
authors.affiliation: Department of Chemistry, Burdwan University, Golapbag, Burdwan 713104, West Bengal, India. pabitracc@yahoo.com.
authors.forename: Siddhartha
authors.initials: S
authors.lastname: Pal
authors.forename: Buddhadeb
authors.initials: B
authors.lastname: Sen
authors.forename: Somenath
authors.initials: S
authors.lastname: Lohar
authors.forename: Manjira
authors.initials: M
authors.lastname: Mukherjee
authors.forename: Samya
authors.initials: S
authors.lastname: Banerjee
authors.forename: Pabitra
authors.initials: P
authors.lastname: Chattopadhyay
mesh_terms: D000171:Acrolein / Q000031:analogs & derivatives / Q000737:chemistry; D002470:Cell Survival / Q000187:drug effects; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D003300:Copper / Q000737:chemistry / Q000494:pharmacology; D031541:Fluorescence Resonance Energy Transfer; D006367:HeLa Cells; D006801:Humans; D006834:Hydrazines / Q000737:chemistry; D008856:Microscopy, Fluorescence; D010084:Oxidation-Reduction; D012235:Rhodamines / Q000737:chemistry; D012545:Schiff Bases / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology
chemical_list: D056831:Coordination Complexes; D006834:Hydrazines; D012235:Rhodamines; D012545:Schiff Bases; C543681:rhodamine B hydrazide; C071678:4-nitrocinnamaldehyde; D000171:Acrolein; D003300:Copper