Au-quantum dot nanocluster electrochemiluminescence coupled with cycling-amplification for sensitive microRNA detection

A novel polyamidoamine (PAMAM) dendrimer-Au nanocluster composite was synthesized, and used to fabricate a new amplified electrochemiluminescence (ECL) signal probe for sensitive detection of microRNA by multiple strand displacement amplification (SDA) strategy. The as prepared PAMAM-Au nanocluster with many amino groups could assemble a large number of quantum dots (QDs) to greatly amplify ECL of the probe. In addition, a new sliver nanocluster (NC) with excellent conductivity and many reactive carboxyl groups was prepared, and used to immobilize a large amount of capture (c1) DNA molecules on the electrode. Moreover, by using bifunctional DNA strand displacement reaction-mediated multiple cycling-amplification technique, a small number of target miRNA could induce to generate abundant DNA (t1) fragments, which was used as a linker to hybridize with c1 DNA on the electrode, and then conjugate many amplified QDs probe. Thus an amplified ECL analytical method for detecting target miRNA was designed, and highly sensitive detection of miRNA was achieved. This newly established strategy paves a new way for homogeneous microRNA detection, which hold great potential for application in early clinical diagnosis.