A general strategy for photoelectrochemical immunoassay using an enzyme label combined with a CdS quantum dot/TiO₂ nanoparticle composite electrode.
Photoelectrochemical (PEC) immunoassay has received increasing attention owing to its good analytical performance and attractive potential for future protein assay. This Letter represents a novel and general strategy for elegant PEC immunoassay of the important cardiac marker troponin T (cTnT) at neutral conditions. Specifically, we first developed an efficient CdS quantum dots (QDs)/TiO2 nanoparticles (NPs) photoelectrode, on the basis of which an exquisite β-galactosidase (β-Gal) catalytic system was integrated with sandwich immunobinding for probing cTnT. In pH 7.4, β-Gal could catalyze the conversion of p-aminophenyl galactopyranoside (PAPG) to p-aminophenol (PAP), which could be easily photo-oxidized to p-quinone imine (PQI). Because the resulting photocurrent was directly related with the target concentration, an innovative PEC immunoassay could be realized for cTnT detection. The neutral operating condition of this protocol would greatly contribute to its wide applicability for protein assay. This work provides the first PEC immunoassay toward cardiac marker and, more significantly, opens a different perspective for future PEC immunoassay development through a general sensing protocol.
State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, Jiangsu, China.
Wei-Wei
WW
Zhao
Ru
R
Chen
Pan-Pan
PP
Dai
Xiang-Ling
XL
Li
Jing-Juan
JJ
Xu
Hong-Yuan
HY
Chen
D055162:Biocatalysis; D019187:Cadmium Compounds / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D007118:Immunoassay / Q000379:methods*; D055668:Photochemical Processes; D045663:Quantum Dots; D013440:Sulfides / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D001616:beta-Galactosidase / Q000378:metabolism*
D019187:Cadmium Compounds; D013440:Sulfides; C034939:cadmium sulfide; C009495:titanium dioxide; D014025:Titanium; D001616:beta-Galactosidase