The Exploration About Photoelectrochemical Biosensor Based On TiO₂ Mesocrystal

As a new kind of chemical analysis method,photoelectrochemical biosensors could rapidly and sensitively monitor biomolecules,which possess remarkable significance in clinical and environmental fields.The photoelectrochemical detection method has the advantages of high sensitivity,low cost,simple equipment,and easy to miniaturization,etc.It shows the unique superiority in analysis field.At present,it is very important to explore new photoactive materials and construct new sensing analysis principles and strategies to expand the application of photoelectrochemical biosensors.In this thesis,we mainly focus on TiO₂ mesocrystal,a new kind of semiconductor material with excellent photoelectric activity to build photoelectrochemical sensor.TiO₂ mesocrystal has a series of advantages,such as the high photoelectric conversion efficiency,good stability and non-toxicity,which plays a vital role in the development of solar cells,and has a favourable application prospect in photoelectrochemical sensing platform.Therefore,the study of TiO₂ nanomaterials has become a hotspot in many fields.In this thesis,three new methods of photoelectrochemical detection based on TiO₂ mesocrystal were developed,and their sensitivities were studied and how to enhance the sensitivities.In first chapter,the work designed a photoelectrochemical biosensing method for concanavalin A assay through graphene-sensitived quasi-octahedral TiO₂ mesocrystal?QOTM?accompanied with non-enzyme labeling.Meanwhile,the preliminary application of TiO₂ mesocrystal was also explored in this work.In second chapter,we created a novel photoelectrochemical sensor for ultrasensitively detecting aflatoxin B1.This strategy was based on the all-carbon nanohybrids as the basic transducer scaffold,and QOTM absorbed dentritic Si phthalocyanines as the bioprobe.A versatile approach for highly sensitive detection of small molecule was supplied in this competitive immunosensor.In third chapter,a PEC immunosensing platform for zearalenone determination was established based on polydopamine sensitized rutile TiO₂ mesocrystals as the self-enhanced PEC matrix.And the signal amplification element was constructed by utilizing the ordered mesoporous cobalt oxide?OMCO?conjugated signal antibodies as the bioprobe.Under optimal conditions,this proposed sandwich-type immunosensor had submitted a fine linear relationship for zearalenone detection ranging from 10-6 to 20 ng/mL.The specificity,precision,and reproducibility were satisfactory for this biosensor,which provided a valuable and versatile protocol in photoelectrochemical bioassay development.