Organic Dots Embedded in Mesostructured Silica Xerogel as High-Performance ECL Emitters: Preparation and Application for MicroRNA-126 Detection.

Unlike the organic micro/nanocrystals prepared using an emerging reprecipitation method, a novel method of embedding 1-pyrenecarboxaldehyde dots (PycDs) into a mesostructured silica xerogel (PycDs@MSX) for use as electrochemiluminescence (ECL) emitters was first proposed to achieve an extremely strong ECL response, with peroxydisulfate (S2O82-) used as a coreactant. In this method, (i) PycDs@MSX could ensure the reversal of the PycDs environment from hydrophobic to hydrophilic and (ii) PycDs@MSX could provide massive porous channels, allowing for access of hydrophilic reactive intermediates (i.e., sulfate anion radicals, SO4•-), which could accelerate the rate of mass transfer and electron transfer between S2O82- and PycDs. Using Ag nanoparticles as a coreaction accelerator and a 3D DNA nanomachine as a signal amplification strategy, the proposed ECL biosensing platform was constructed and achieved ultrasensitive detection of microRNA-126 with an excellent linear range (from 100 aM to 100 pM) and a low detection limit (13.0 aM). More importantly, this work not only developed an innovative avenue to improve the ECL efficiency of organic emitters in aqueous phases but also provided a powerful strategy for biochemical analysis and disease diagnosis applications.