Aggregation of thermally activated delayed fluorescence molecules to boost solid electrochemiluminescence efficiency for biosensing of protein-specific glycoforms

Low quantum yield and insufficient exciton utilization of nanoemitters are great obstacles to achieving their practical electrochemiluminescence (ECL) applications. Here an aggregation strategy of thermally activated delayed fluorescence molecules was designed to reduce the energy gap between the lowest excited singlet and triplet states, and accelerate the reverse intersystem crossing of triplet excitons to the excited singlet state, which increased the exciton utilization, leading to longer delayed fluorescence lifetime and greatly boosted the quantum yield up to 87.5%, using a previously reported DMAC-TRZ as a model. The aggregation could be conveniently performed by increasing the water content in the tetrahydrofuran solution of DMAC-TRZ. Benefiting from the high quantum yield, the solid ECL efficiency was broken through to 62.9%, much higher than the limit of 25%, and a sensitive ECL imaging method was thus proposed for simultaneous high-throughput detection of mucin1-specific sialic acid and fucose on cells by combining a Nt.BbvCI-aided cleavage recycling to obtain the detection samples, and a DNA array to capture the detection samples and then recognize the ECL probes. This method showed good reliability and could be expanded to detect the glycans on different proteins by altering the protein aptamer sequence. This work charts a fresh course for exploiting highly efficient ECL emitters and extends their applications in ECL bioanalysis.