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Enzyme catalytic amplification of miRNA-155 detection with graphene quantum dot-based electrochemical biosensor

Hu, Tianxing, Zhang, Le, Wen, Wei, Zhang, Xiuhua, Wang, Shengfu
Biosensors & bioelectronics 2016 v.77 pp. 451-456
DNA, biosensors, catalytic activity, color, detection limit, electrochemistry, electrodes, gold, graphene, hydrogen peroxide, microRNA, oligodeoxyribonucleotides, oxidation, peroxidase, quantum dots
A specific and sensitive method was developed for quantitative detection of miRNA by integrating horseradish peroxidase (HRP)-assisted catalytic reaction with a simple electrochemical RNA biosensor. The electrochemical biosensor was constructed by a double-stranded DNA structure. The structure was formed by the hybridization of thiol-tethered oligodeoxynucleotide probes (capture DNA), assembled on the gold electrode surface, with target DNA and aminated indicator probe (NH2-DNA). After the construction of the double-stranded DNA structure, the activated carboxyl groups of graphene quantum dots (GQDs) assembled on NH2-DNA. GQDs were used as a new platform for HRP immobilization through noncovalent assembly. HRP modified biosensor can effectively catalyze the hydrogen peroxide (H2O2)-mediated oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB), accompanied by a change from colorless to blue in solution color and an increased electrochemical current signal. Due to GQDs and enzyme catalysis, the proposed biosensor could sensitively detect miRNA-155 from 1fM to 100pM with a detection limit of 0.14fM. High performance of the biosensor is attributed to the large surface-to-volume ratio, excellent compatibility of GQDs. For these advantages, the proposed method holds great potential for analysis of other interesting tumor makers.