Ultrasensitive serological digoxin fluorescence sensor based on cascade amplification of entropy-driven DNA nanomachine and proximity ligation assay

Abstract

A nanobiosensor was prepared by DNA nanomachine based on proximity ligation assay (PLA) for the detection of digoxin (DIG) in serum. In this sensor the DNA nanomachine releases a large number of signal probes (SP) after addition of DIG, which participate in PLA as the connector strand, initiating real-time quantitative polymerase chain reaction (qPCR) and producing fluorescence signals. For the benefit of clinical therapeutics, we determined the detection range of 0.1 ∼ 5 ng/mL. Under the optimal experimental conditions, the cycle threshold (Ct) value showed a good linear relationship with DIG concentrations, and the detection limit was as low as 0.06 ng/mL (3σ). This method achieved the ultrasensitive detection of DIG by signal amplification and was successfully used for the detection of DIG in real serum, which has a good potential for application in the field of therapeutic drug monitoring.