A visible light photoelectrochemical sandwich aptasensor for adenosine triphosphate based on MgIn2S4-TiO2 nanoarray heterojunction

This work designed a MgIn 2 S 4 -TiONA heterojunction by growing MgIn 2 S 4 nanoplates on TiO 2 nanowire array (TiONA) for preparation of visible light photoelectrochemical (PEC) sensing platform. The heterojunction exhibited strong absorption of visible light, large surface area and high loading of biomolecules , leading to high sensing sensitivity. Using adenosine triphosphate (ATP), a marker of cell vitality, as the target model, a PEC sandwich aptasensor was constructed by immobilizing capture DNA 1 on MgIn 2 S 4 surface. In the presence of ATP and signal DNA 2 with terminal ferrocene as the electron donor , a sandwiched DNA 1 -ATP-DNA 2 complex could be formed on the PEC aptasensor. The aptasensor showed excellent performance with a wide linear range from 50 fM to 100 nM and a detection limit of 20 fM. The sensing performance including specificity, reproducibility, stability and practical use were also evaluated, showing promising application of the MgIn 2 S 4 -TiONA heterojunction in PEC biosensing.