Hybridization chain reaction and gold nanoparticles dual signal amplification for sensitive glucose detection

Ultrasensitive electrochemical method was established for glucose detection coupling hybridization chain reaction (HCR) and positively charged gold nanoparticles ((+)AuNPs) dual signal amplification. Molecular beacon (MB) was initially assembled onto gold electrode surface in their folded states. Hybridization of MB with detection probe opened the stem-loop structure of it, then another exposed part of it opened two ferrocene (Fc) modified DNA hairpins (H-1 and H-2) and induced HCR, which produced a strong current signal due to the formation of numerous Fc on such double-helix. Meantime, (+)AuNPs were electrostatically adsorbed onto such double-helix to amplify electrochemical signal. However, if the detection probe was incubated with the mixture of glucose, glucose oxidase (GOD) and Fe2+ firstly, it would be cleaved into DNA fragments and could not open the stem-loop structure of MB, accordingly resulted in no HCR happen and (+)AuNPs adsorption. Upon optimal conditions, a low detection limit of 21 pM for glucose detection was obtained. Moreover, the practicability of the assay in glucose detection of human serums was studied as well. (C) 2015 Elsevier B.V. All rights reserved.