A portable solar-driven ratiometric photo-electrochromic visualization biosensor for detection of ochratoxin A

Photoelectrochemical (PEC) biosensors have been widely studied and applied due to unique advantages. But the requirement of electrochemical workstation and light source limits the development of portable PEC biosensors. In this work, a portable solar-driven visualization PEC biosensor has been successfully developed to completely get rid of instruments requirement. This biosensor is fabricated onto a small ITO electrode which may be divided into two modules, one is the detection module and the other is the reference module. Each module is composed of two regions. Co, N-TiO2/3DGH (three-dimensional graphene hydrogel) nanocomposite is used to construct the photoelectric sensing region and the electrochromic material Prussian Blue (PB) is used in the visual region. The quantification is through the chromaticity ratio of visual regions on the two modules. Based on this, the proposed portable visual biosensor has been successfully applied to the detection of ochratoxin A (OTA). A good linear range (1 ng/mL-500 ng/mL) was obtained with a detection limit of 0.29 ng/mL. Due to its high accuracy and portability, the sensor will bring bright prospects for research in the fields of bioanalysis, food testing and so on.