title: Surface functionalized fluorescent CdS QDs: selective fluorescence switching and quenching by Cu(2+) and Hg(2+) at wide pH range.
abstract: Fluorescent CdS QDs surface functionalized with organic functional unit, N-(2-hydroxybenzyl)-cysteine (L), has been synthesized using simple wet chemical approach in a single step. The as-prepared L-CdS QDs showed good fluorescence at 542 nm. Fluorescence sensor studies of L-CdS QDs showed selective fluorescence switching (542-600 nm) for Cu(2+) ions and quenching for Hg(2+) ions in aqueous solution. High selectivity of L-CdS QDs for Cu(2+) ions have been confirmed by interference studies. Interestingly, L-CdS QDs showed enhancement in the fluorescence intensity (4-fold) upon reducing pH from 2.0 to 10.0 without changing λmax. Importantly, selective fluorescent switching and quenching for Cu(2+) and Hg(2+) was observed from 2.0 to 10.0 pH range. The practical application of L-CdS QDs fluorescence sensing for Cu(2+) and Hg(2+) have also been demonstrated in real samples such as river, pond, tap and ground water.
authors.affiliation: School of Chemical & Biotechnology, SASTRA University, Thanjavur 613401, Tamil Nadu, India.
authors.forename: S
authors.initials: S
authors.lastname: Akshya
authors.affiliation: School of Chemical & Biotechnology, SASTRA University, Thanjavur 613401, Tamil Nadu, India.
authors.forename: P S
authors.initials: PS
authors.lastname: Hariharan
authors.affiliation: School of Chemical & Biotechnology, SASTRA University, Thanjavur 613401, Tamil Nadu, India.
authors.forename: V Vinod
authors.initials: VV
authors.lastname: Kumar
authors.affiliation: School of Chemical & Biotechnology, SASTRA University, Thanjavur 613401, Tamil Nadu, India. Electronic address: philip@biotech.sastra.edu.
authors.forename: Savarimuthu Philip
authors.initials: SP
authors.lastname: Anthony
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008628:Mercury / Q000737:chemistry*; D045663:Quantum Dots / Q000737:chemistry* / Q000648:ultrastructure; D013050:Spectrometry, Fluorescence; D013440:Sulfides / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D019187:Cadmium Compounds; D013440:Sulfides; C034939:cadmium sulfide; D014867:Water; D003300:Copper; D008628:Mercury
keywords: CdS fluorescence sensor; CdS quantum dots; Cu(2+) sensor; Fluorescent quantum dots; Hg(2+) sensor