A "signal-off" electrochemiluminescence biosensing platform based on high efficiency quenching effect of...

A "signal-off" Electrochemiluminescence (ECL) biosensing platform based on Glutathione-Au nanoclusters covered reduced graphene oxide (GSH-Au NCs@rGO) and Au nanoparticles functionalized copper oxide (Au@CuO) was fabricated. The GSH ligand protected Au NCs were spontaneously adsorbed on the rGO surface via Van der Waals force. As ECL emitters, GSH-Au NCs@rGO not only support more luminophores and immobilization of bioreceptor units also facilitates mass transfer, accelerating ECL excitation to obtain a higher ECL signal intensity. Remarkably, Au@CuO with good biocompatibility was first applied as a quenching probe. Au@CuO (acceptor)-dependent resonance energy transfers (RET) with GSH-Au NCs@rGO (donor) could effectively quenched the ECL intensity to a reasonable range for requirements of trace analysis. The proposed ECL biosensing platform was evaluated with cardiac troponin I (cTnI) as a model analyte, achieving a low detection limit of 54.95 fg/mL. This strategy may provide as new approaches for the sensitive detection of biomarkers in the early clinical diagnosis of diseases.