Tris(2-carboxyethyl)phosphine-mediated immobilization of thiolated DNA on gold nanoclusters and its application in multiplex microRNA detection

Quick and efficient immobilization of DNAs on gold nanoclusters (AuNCs) has a substantial impact on nanoscale applications relative to molecular recognition and patterned assembly. We found that in the presence of tris(2-carboxyethyl)phosphine (TCEP), chemisorption of thiolated DNA on the AuNC surface could be accomplished within 1.5 h, which was dramatically shorter than the incubation time needed in the conventional thiolate exchange reactions. Based on this observation, a core-shell-satellite nanocomposite consisting of magnetic nanoparticle , silica coating, and AuNCs (Fe 3 O 4 NPs@SiO 2 @AuNCs) was fabricated, on which a fluorescent hairpin probe was anchored with the assistance of TCEP. Integrated with duplex-specific nuclease (DSN)-assisted target recycling strategy, the sensing platform could simultaneously detect microRNA-21 and microRNA-141 with detection limits of 0.020 and 0.017 pM, respectively. The feasibility of the developed immobilization approach might significantly advance the use of DNAs and AuNCs in analytical sciences and clinical research.