Electrochemiluminescence Biobarcode Method Based on Cysteamine-Gold Nanoparticle Conjugates

The recently developed DNA gold nanoparticle (DNA-GNP) biobarcode assay provides polymerase chain reaction (PCR)-like sensitivity for nucleic acid and protein targets without a need for enzymatic amplification. However, application of the conventional assay is challenged by its complex, expensive, time-consuming, and labor-intense procedure. Herein, we present a new electrochemiluminescence (ECL) biobarcode method based on cysteamine GNP conjugates. In this strategy, an ECL nanoprobe is fabricated that relies on GNP that is modified with tris-(2,2'-bipyridyl) ruthenium (TBR) labeled cysteamine to boost ECL signals and single strand DNA for target recognition. Specifically, a sandwich complex that consists of a biotin labeled capture probe, target DNA, and cysteamine GNP conjugate is captured by magnetic microparticles (MMPs) and subsequently identified by the ECL signals from loaded TBR. With the use of the developed probe, a limit of detection as low as 100 fM can be achieved and the assay exhibits excellent selectivity for single-mismatched DNA detection even in human serum. The proposed ECL based method should have wide applications in diagnosis of genetic diseases due to its high sensitivity, simplicity, and low cost.