Ru(bpy)32+-Silica@Poly-L-lysine-Au as labels for electrochemiluminescence lysozyme aptasensor based on 3D graphene

In this work, the feasibility of a novel sensitive electrochemiluminescence aptasensor for the detection of lysozyme using Ru(bpy)32+-Silica@Poly-L-lysine-Au (RuSiNPs@PLL-Au) nanocomposites labeling as an indicator was demonstrated. The substrate electrode of the aptasensor was prepared by depositing gold nanoparticles (AuNPs) on 3D graphene-modified electrode. The lysozyme binding aptamer (LBA) was attached to the 3D graphene/AuNPs electrode through gold-thiol affinity, hybridized with a complementary single-strand DNA (CDNA) of the lysozyme aptamer labeled by RuSiNPs@PLL-Au as an electrochemiluminescence intensity amplifier. Thanks to the synergistic amplification of the 3D graphene, the AuNPs and RuSiNPs@PLL-Au NPs linked to Ru(bpy)32+-ECL further enhanced the ECL intensity of the aptasensor. In presence of lysozyme, the CDNA segment of the self-assembled duplex was displaced by the lysozyme, resulting in decreased electrochemiluminescence signal. Under the optimized conditions, the decrease in electrochemiluminescence intensity varied proportionally with the logarithmic concentration of the lysozyme from 2.25 × 10-12 to 5.0 × 10−8 mol L−1, and the detection limit was estimated to 7.5 × 10-13 mol L−1. The aptasensor was further tested in real samples and found reliable for the detection of lysozyme, thus holding great potential application in food safety researches and bioassay analysis.