A photoelectrochemical biosensor for o-aminophenol based on assembling of CdSe and DNA on TiO2 film electrode

• CdSe QDs and DNA were assembled on liquid phase deposited TiO2 film.
• CdSe and DNA effectively enhanced the absorption of TiO2 film to visible light.
• DNA improved the photoelectrochemical response of o-aminophenol (OAP).
• DNA–CdSe/TiO2 showed sensitive PEC response to OAP under visible light irradiation.

A novel photoelectrochemical (PEC) biosensing platform was constructed by assembling CdSe quantum dots (QDs) and DNA on liquid phase deposited TiO2 (DNA–CdSe/TiO2) film electrode. The transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis indicated that CdSe QDs were homogeneously assembled on TiO2 film. The UV–visible diffuse reflectance spectra (DRS) showed that CdSe and DNA could effectively enhance the absorption of TiO2 film to visible light. The obtained electrode showed a sensitive PEC response to o-aminophenol (OAP) under visible light irradiation. Due to the interaction between DNA and OAP, the response of OAP was improved by DNA immobilized on the sensing film. Under optimized conditions, the photocurrent was linearly proportional to OAP in the concentration range from 4.0×10−7 to 2.7×10−5 mol L−1, with a detection limit (3 S/N) of 8.0×10−8 mol L−1. The novel strategy could provide a fast and sensitive method for OAP determination.