Stretch-stowage-growth strategy to fabricate tunable triply-amplified electrochemiluminescence immunosensor for ultrasensitive detection of pseudorabies virus antibody.

Triply amplified electrochemical biosensors have attracted particular attention in the detection of low-abundance biomarkers. The universal construction routes for nonenzymatic triply amplified and even multiply amplified biosensors are extremely desirable but remain challenging. Here, we proposed a "stretch-stowage-growth" strategy to tunably fabricate a nonenzymatic triply amplified or multiply amplified electrochemiluminescence (ECL) immunosensor for ultrasensitive determining pseudorabies virus (PrV) antibody. Based on the matrix role of gold nanoparticle-graphene nanosheet (Au-GN) hybrids, carrier role of silicon nanoparticles (SNPs) and bridge role of "biotin-streptavidin-biotin" (B-SA-B) structure, the establishment processes were defined as "stretch", "stowage", and "growth", respectively. Relying on the interaction of antigen-antibody and of B-SA, the "Au-GN/PrV (Ag)/PrV antibody (Ab1)/biotinylated IgG (B-Ab2)/SA/biotinylated Ru(bpy)3(2+)-encapsulated SNPs (B-Ru@SNPs)" triply amplified biosensor could be fabricated and exhibited better analytical performance not only toward monoclonal PrV antibody with a linear detection range from 50 ng mL(-1) to 1 pg mL(-1) and a detection limit of 0.40 pg mL(-1), but also toward actual serum samples when compared with enzyme-linked immunosorbent assay and fluorometry. Furthermore, multiply amplified biosensors could be conveniently fabricated by controllably repeating the combination of B-Ru@SNPs and SA to form the B-SA-B structure. After it was repeated three times, the multiply amplified biosensor stretched to the maximum of signal amplification and achieved a luminescence quantum efficiency about 23.1-fold higher than the triply amplified biosensor. The tunable biosensor exhibits good stability, acceptable reproducibility and accuracy, suggesting its potential applications in clinical diagnostics.