Paper-based Photoelectrochemical Biosensor Constructed With Zinc Oxide/quantum Dots Nanomaterials

Photoelectrochemical biosensor is a kind of analytical device which is based on the photoelectric conversion characteristics of substances and analyzes the substances to be detected through the process of chemical/biological recognition.Photoelectrochemical biosensor mainly includes photoelectric conversion unit and sensor recognition unit,in which the selection of photoelectric materials and the design of sensor recognition strategy are the key to the construction of highly sensitive photoelectrochemical biosensor.The photoelectrochemical analysis method takes light as the excitation signal and detects the electrical signal.Benefit from the separation between the optical signal and the electrical signal,the system has a lower background signal.Photoelectrochemical analysis has the advantages of rapid response,low cost,simple equipment,low background signal and high sensitivity,so it has attracted wide attention in early disease diagnosis,biological analysis and environmental detection.During the master’s degree,the main work is based on ZnO nanomaterials with different morphologies as basic optoelectronic materials and different kinds of quantum dot nanomaterials as photosensitive materials.Combined with different signal amplification strategies and laboratory research on microfluidic paper chip,two paper-based photoelectrochemical biosensors with high sensitivity and specificity were constructed for the detection of nucleic acid.It provides a basis for early diagnosis of cancer.The main research work is as follows:(1)The research of photoelectrochemical biosensor based on cascaded photoactive materials and triple helix molecular switch.Gold nanoparticles were grown on paper chips by in-situ growth method to enhance the conductivity and biocompatibility of paper substrates.The rod-like ZnO nanomaterials were sensitized by cadmium telluride quantum dots of different sizes with different groups to form a cascaded optoelectric layer to achieve a outstanding photocurrent signal amplification.The photoelectrochemical analysis is combined with the triple helix molecular switching strategy for the first time.When the target was existed,the change of the photocurrent response is caused by the change of the switching state of the triple helix molecule,and the sensitive and specific detection of HIV-1 is realized.(2)The research of the dual-mode photoelectrochemical biosensor based on cerium dioxide octahedron modified by gold nanoparticles as a multi-functional signal regulator.A paper-based analysis device with foldable and colorimetric region was designed independently.Firstly,zinc oxide nanoflowers were synthesized by hydrothermal method and modified on the paper chip,and low toxic indium silver selenide quantum dots were selected to sensitize zinc oxide nanoflowers,achieving an excellent initial photocurrent signal.In addition,cerium dioxide octahedron modified by gold nanoparticles was introduced into the electrode system by specific hybridization between DNA chains,and its multi-functional quenching effect was used to quench the photocurrent signal,which greatly improved the sensitivity of the biosensor.When the target DNA existed,the cerium dioxide octahedron modified by gold nanoparticles leaved the working electrode and transfered to the colorimetric region.On the one hand,it leaded to an increase in photocurrent response,on the other hand,it utilized the characteristics of its peroxidase-like enzyme to catalyze the formation of color reaction,thus realizing the visual detection of the target DNA.