High-throughput immunosensor chip coupled with a fluorescent DNA dendrimer for ultrasensitive detection of cardiac troponin T.

A novel fluorescence (FL) imaging platform was established for ultrasensitive and rapid detection of cardiac troponin T (cTnT), based on a high-throughput immunosensor chip and a DNA dendrimer capped with a large number of fluorescent dyes (FDD@Cy5). Through an enzyme-free and step-by-step strategy, FDD@Cy5 was self-assembled facilely. After the formation of a sandwich immunocomplex and biotin-streptavidin conjugation, FDD@Cy5 could be captured on the chip. FL signals emerged from Cy5 under external light and the enrichment of Cy5 on the dendrimer led to signal amplification. A FL image containing 90 spots could be collected instantaneously by laser confocal scanning microscopy and the brightness of all the spots corresponded to the concentrations of target cTnT. Under optimal conditions, the immunosensor chip coupled with FDD@Cy5 exhibited an excellent detection limit of 0.10 pg L, a wide linear range from 0.20 pg L to 2.0 ng L, a sample consumption down to 3.0 μL and a maximum throughput of 45 tests per h. The proposed approach was also applied to cTnT quantitation in serum samples with acceptable accuracy, providing a new avenue for early diagnosis and the prognosis evaluation of acute myocardial infarction.