Photoelectrochemical Sensors Based On Composite Photoanodes And Their Biological Applications

In recent years,photoelectrochemical?PEC?sensors are a hot research field in sensor research,which mainly because the photoelectrochemical analysis method uses the energy convert between light energy,electrical energy,and chemical energy,and through the photoelectrochemical instruments collect the photocurrent by light excitation to come true the detection of objects.The photoelectrochemical sensors have the following advantages:a simple structure,low price,easy to miniaturize and so on.At present,in the field of the photoelectrochemical biosensors,most researchers focus their attention on the molecular recognition unit of the sensor,which use the increasingly complex amplification strategies to amplify the detected biomolecule for achieve a lower detection range,but to study the material aspects less.In order to solve these problems,this thesis studied a new type of electro-optically active materials and the preparation methods of TiO₂ photoelectric materials in order to obtain a simple preparation method with good stability and high sensitivity.The main research content are as follows:Firstly,we developed a new type of photoelectrically active material,MoS₂-AuNPs,for photoelectrochemical sensor detection.The study found that after MoS₂-AuNPs were annealed,the photoelectric conversion efficiency of the material has been greatly improved.In the molecular recognition unit,the biotin-avidin system is used,which is a simple amplification strategy to detect the signal.The experimental results show that the MoS₂-AuNPs become more stable after annealing,and the biocompatibility of the materials is becoming better.The molecular recognition unit strategy design is simple and effective,which can realize the detection of specific substances in a complex environment with high sensitivity.With its wide application prospects,it provides new options for follow-up researchers in the selection of active materials for photoelectrochemical sensors.Secondly,a simple,stable and high-efficiency photoelectrochemical enzyme sensor is constructed by using TiO₂ by spin coating and drop coating.The first method is to prepare TiO₂ layer by spin coating method and use nafion to fix Glucose Oxidase?GOx?.The second method is to prepare TiO₂ layer by dropping TiO₂ solution,and glutaraldehyde is used as cross-linker to fix GOx.Finally,both methods are found that can get a better detection range.Due to the difference in the surface area of the TiO₂ photoanode,the TiO₂ layer prepared by the spin coating method can measure a smaller detection range,and the method using the TiO₂ solution has a larger detection range.By comparison,the two sensors can be used for different occasions,providing a new solution for the detection of glucose.Thirdly,the composite photoanode materials TiO₂-AuNPs were prepared for photoelectron--chemical sensors.Five different methods for preparing TiO₂-AuNPs were compared.Finally,a method of preparing TiO₂ layer by spin coating tetraisopropyl titanate with a high degree of automation and an electrochemical deposition method for preparing Au NPs layer was chosen.The electrode uniformity obtained by this method is better,less disparate and can be used for future scale production.Later research found that after electrochemical deposition of the Au NPs layer and under annealing,the band gap of the material became narrower.Under the same light intensity conditions,the photoelectric conversion efficiency is greatly increased,a large photocurrent is generated,and the sensor performance could be further improved.In the biomolecule recognition unit,the photocurrent is further amplified using the exciton energy transfer?EET?effect of CdTe quantum dots and Au NPs,and a highly sensitive and selective photoelectrochemical sensor was obtained.In summary,the application of MoS₂-AuNPs,a new type of photovoltaic active material,and the re-expansion of TiO₂,a more mature active material,provide numerous options for the commercialization of photoelectrochemical biosensors in the future,and possess a good application prospects.