title: Formation of surface traps on quantum dots by bidentate chelation and their application in low-potential electrochemiluminescent biosensing.
abstract: Bidentate chelation, meso-2,3-dimercaptosuccinic acid (DMSA), was used as a stabilizer for the synthesis of CdTe quantum dots (QDs). The bidentate chelate QDs, characterized with FT-IR, PL, and UV/Vis spectroscopy; element analysis; and high-resolution transmission electron microscope, exhibited surface traps due to the large surface/volume ratio of QD particle and the steric hindrance of the DMSA molecule. The unpassivated surface of the QDs produced a narrower band gap than the core and electrochemiluminescent (ECL) emission at relatively low cathodic potential. In air-saturated pH 7.0 buffer, the QDs immobilized on electrode surface showed an intense ECL emission peak at -0.85 V (vs. Ag/AgCl). H(2)O(2) produced from electrochemical reduction of dissolved oxygen was demonstrated to be the co-reactant, which avoided the need of strong oxidant as the co-reactant and produced a sensitive analytical method for peroxidase-related analytes. Using hydroquinone/horseradish peroxidase/H(2)O(2) as a model system, a new, reagentless, phenolic, ECL biosensor for hydroquinone was constructed, based on the quenching effect of ECL emission of QDs by consumption of co-reactant H(2)O(2). The biosensor showed a linear range of 0.2-10 μM with acceptable stability and reproducibility. This work opens new avenues in the search for new ECL emitters with excellent analytical performance and makes QDs a more attractive alternative in biosensing.
authors.affiliation: MOE Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Liu
authors.forename: Lingxiao
authors.initials: L
authors.lastname: Cheng
authors.forename: Jianping
authors.initials: J
authors.lastname: Lei
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.forename: Huangxian
authors.initials: H
authors.lastname: Ju
mesh_terms: D015374:Biosensing Techniques; D002104:Cadmium / Q000737:chemistry*; D002614:Chelating Agents / Q000138:chemical synthesis* / Q000737:chemistry; D004563:Electrochemistry; D008163:Luminescent Measurements; D015394:Molecular Structure; D045663:Quantum Dots; D013056:Spectrophotometry, Ultraviolet; D004113:Succimer / Q000737:chemistry*; D013691:Tellurium / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D002104:Cadmium; D004113:Succimer; D013691:Tellurium