Integration of phosphate functionalized Pt/TiO and Ru(bpy) sensitization for ultrasensitive assay of adenosine deaminase activity on a novel split-typed PEC aptasensor.

To date, it is still a challenge for high-performance photoelectrochemical (PEC) assay of low-abundance adenosine deaminase (ADA) in fundamental research and clinical diagnosis. Herein, phosphate-functionalized Pt/TiO (termed PO/Pt/TiO) was prepared as ideal photoactive material to develop a split-typed PEC aptasensor for detection of ADA activity, coupled by a Ru(bpy) sensitization strategy. We critically studied the effects of the PO and Ru(bpy) on the detection signals, and discussed the signal-amplified mechanism. Specifically, hairpin-structured adenosine (AD) aptamer was splited into single chain via ADA-induced catalytic reaction, and subsequently hybridized with complementary DNA (cDNA, initially coating on magnetic beads). The in-situ formed double-stranded DNA (dsDNA) was further intercalated by more Ru(bpy) to amplify the photocurrents. The resultant PEC biosensor showed a broader linear range of 0.05-100 U L and a lower limit of detection (0.019 U L), which can fill the blank for analysis of ADA activity. This research would provide some valuable insights for building advanced PEC aptasensors in ADA-related research and clinical diagnosis.