Electrochemical synthesis of silver nanoclusters on electrochemiluminescent resonance energy transfer amplification platform for Apo-A1 detection

Herein, a novel electrochemiluminescence resonance energy transfer (ERET) strategy between in situ electro-generated silver nanoclusters (AgNCs) as the donor and Ru(bpy)(2)(5-NH2-1,10-phen)Cl-2 (Ru(II)) as the acceptor was reported, which was applied for the construction of a ultrasensitive immunosensor for the determination of apolipoprotein-A1 (Apo-A1). Notably, the Ag NCs were in suit electro-reducted on glassy carbon electrode (GCE) based on a simple, fast and controllable electrochemical technique, which acted as not only biocompatible ECL emitters, but also protein immobilization platform via Ag-N or Ag-S bond. Subsequently, the acceptor probe was constructed by modifying Ru(II) and secondary antibody on the nanocarriers of carboxyl-functionalized MWCNTs. Based on the sandwiched immunoassay method, the ECL signals declining at 449 nm (Ag NCs) and the increasing at 650 nm (Ru(II)) both reflect the amount of Apo-A1. By measuring the ratio of ECL650 nm/ECL449 nm, we could accurately quantify the concentration of Apo-A1 in range from 1.0 pg/mL to 1.0 ng/mL and limit of detection down to 0.33 pg/mL, which opened up a new research direction for ultrasensitive ECL bioanalysis based metal NCs.