Ultrasensitive electrochemiluminescence biosensors based on programmable aptazyme-induced hybridization chain reaction for detecting adenosine triphosphate and quinine

Abstract

Biosensors with programmability and universal applicability that simplify the detection of biomolecules are highly valuable. Herein, a programmable-component electrochemiluminescence biosensor based on an aptazyme-induced hybridization chain reaction and DNA-templated silver nanoclusters has been developed. An aptazyme-induced hybridization chain reaction system was designed, wherein aptazymes composed of a split aptamer and RNA-cleaving DNAzyme could recognize the target and regulate the activity of DNAzyme. Aptazymes activated by the target cyclically cleaved the substrate to produce short-ssDNA as converted signals, which were captured by engineering tetrahedral-DNA to trigger hybridization chain reaction, hence forming long dsDNA with nicks on the surface electrode. These dsDNA molecules were pre-programmed with cytosine (C)-rich sequences at the nick site, and silver nanoclusters could be synthesized in situ, generating an amplified electrochemiluminescence signal. Thus, the constructed multilevel-amplified adenosine triphosphate (ATP) electrochemiluminescence aptasensor showed good sensitivity, selectivity, and reconfiguration with a linear range from 0.1 pM to 10 nM and a limit of detection of 38.2 fM. Subsequently, an electrochemiluminescence biosensor for the detection of quinine was constructed using the same design, by replacing the ATP aptamer of aptazymes with the quinine aptamer. The quinine electrochemiluminescence biosensor was also significantly sensitive with a linear range from 10 pM to 1 μM and a limit of detection of 3.7 pM, indicating flexibility of the proposed strategy, which can be extended to fabricate other aptasensors.