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Formation of Surface Traps on Quantum Dots by Bidentate Chelation and Their Application in Low‐Potential Electrochemiluminescent Biosensing
Author(s) -
Liu Xuan,
Cheng Lingxiao,
Lei Jianping,
Liu Hui,
Ju Huangxian
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201001738
Subject(s) - quantum dot , biosensor , chelation , nanotechnology , denticity , chemistry , materials science , inorganic chemistry , metallurgy , metal
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 μ M 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.