Enhancement of the ssDNA probe anchoring capacity on photoelectrochemical biosensor by poly-adenine modified ssDNA probe/Au interface

Abstract

Semiconductor/bio-probe interface, which is very important for a photoelectrochemical (PEC) biosensor, because it supports the photocarrier transport process and specific probe anchoring. This paper presents a BiVO4/Au PEC biosensor, which a poly-adenine (poly-A) modified single stranded DNA (ssDNA) probe/Au interface is developed first time to solve the problems mentioned earlier. This PEC biosensor achieves a detection of limit (LOD) of 3 × 10−16 mol/L with a linear detection range of 1 × 10−15 mol/L ∼ 1 × 10−9 mol/L for tumor biomarker miRNA-155 detection. Density functional theory (DFT)calculation, chronoamperometry and surface photovoltage indicate that ploy-A added at the 5′-ssDNA presents a specific stable adsorption energy with the Au nanoparticles on the BiVO4 photoanode. Benefit of the robust interface, the photocarrier transport process from the BiVO4 to liquid and detection specificity of this PEC biosensor were enhanced largely. Thus, this work provides a feasible strategy to help developing efficient semiconductor/ssDNA probe interface on PEC biosensor.