Preparation Of Anthocyanin Sensitized Polyindole Photoelectric Active Materials And Their Biosensor Applications

Photoelechemical（PEC）detection is a detection method that combines the advantages of photochemistry and electrochemistry.It has the advantages of easy operation,low background signal,high sensitivity,portability,and speed analysis.Photoelectric materials are an indispensable component of photoelectric chemical sensors,which determine the sensitivity of the sensor.Polyindole materials in polymer conductive polymers have good photoelectric activity and can display stable photoelectric signals under light conditions.At the same time,it also has the advantages of large specific surface area,good stability,and easy modification,especially in the field of photoelectric chemical sensors.Due to its advantages of low cost,no pollution,and easy availability,natural dye molecules have become an attractive sensitizer instead of organic dyes.Anthocyanins are a natural dye sensitizer with good performance,which has the advantages of simple extraction,low extraction cost,non-toxic,pollution-free,and good stability.They can be used as natural sensitizers for dye sensitized solar cells.Anthocyanin sensitized polyindole materials and heterojunction composite materials formed from polyindole may have better photoelectric activity.In this paper,a series of photoelectric chemical sensors with high photoelectric activity and good sensitivity have been prepared by combining anthocyanin sensitized polyindole with other inorganic materials as a basic photoelectric active material.The main contents are as follows:1.Detection of competitive photoelectric chemical sensors based on anthocyanin sensitized La₂Ti₂O₇/P5FIn heterojunctionsα-fetoproteinIn this work,a PEC sensor based on anthocyanin sensitized La₂Ti₂O₇/P5FIn p-n heterojunction has been constructed,which can achieve the sensitive detection ofα-fetoprotein（AFP）.The composite material formed by sensitizing La₂Ti₂O₇and P5FIn with anthocyanins has excellent photoelectric properties.Homogeneous cadmium selenide quantum dots（Cd Se QDs）were synthesized by wet chemical method.AFP and glucose oxidase（GOD）were combined with cadmium selenide quantum dots to form AFP-Cd Se-GOD composite materials used as markers.AFP and AFP-Cd Se-GOD complexes were combined on anthocyanin sensitized La₂Ti₂O₇/P5FIn electrodes and applied to the detection of AFP.Cd Se QDs can catalyze the production of hydrogen peroxide from glucose as an electron donor,eliminate photogenerated electron holes in the valence band of cadmium selenide quantum dots,and reduce the recombination of electrons and holes in cadmium selenide quantum dots.The effective energy level matching between cadmium selenide quantum dots and the conduction band of La₂Ti₂O₇expands the light absorption range,allowing the cadmium selenide quantum dots excited by visible light to inject electrons into La₂Ti₂O₇,thereby enhancing the photocurrent.The addition of AFP-Cd Se-GOD will compete with AFP,again enhancing the sensitivity of the sensor,and ultimately achieving sensitive detection of AFP.The results show that the constructed AFP competitive photoelectric chemical sensor has a large linear detection range of 0.0001-100 ng ml^-1,and a detection limit of 0.033 pg m L^-1.It has good sensitivity and stability,and also exhibits good performance in practical applications.This work provides a feasible method for achieving excellent photoelectric chemical biosensors for detecting AFP and other proteins.2.Detection of carcinoembryonic antigen using a signal enhancement photoelectric chemical sensor based on anthocyanin sensitized polyindole materialIn this work,a signal enhancement photoelectric immunosensor based on anthocyanin sensitized P5ICA was constructed.P5ICA is an organic polymer with the CEA is detected,In₂S₃@TiO₂ heterojunctions are compounded with anthocyanin sensitized P5 ICA materials.This behavior can accelerate the electron transfer efficiency of the material,making the photoelectric signal larger.The photocurrent intensity the PEC sensor improve after the functionalized by avidin-In₂S₃@TiO₂ marking,and achieves a signal on state.In addition,the fixation process of avidin related to biotin involves only a single attachment point of a biological molecule.The introduction of avidin allows the sensor to complete the recognition of markers and antigens through specific recognition of biotin proteins and avidin,which is conducive to immune response and further improves the sensitivity of the PEC sensor.After testing,it was found that the constructed PEC immunosensor not only has high sensitivity,but also has good stability,high selectivity,and good repeatability.The immunosensor used to detect CEA has a linear range of 0.01-500 ng mL^-1 and a detection limit of 0.0033 ng mL^-1.This study has also shown good performance in practical testing,providing a new approach for the detection of substances such as CEA.3.Detection of CYFRA21-1 using a sandwich type photoelectric chemical sensor based on anthocyanin sensitized ZnO/P5FIn heterojunctionIn this work,a sandwich type PEC immunosensor based on anthocyanin sensitized ZnO/P5FIn p-n heterojunction was designed for the quantitative detection of cytokeratin-19 fragments（CYFRA21-1）in serum.In this study,two materials,anthocyanin sensitized P5FIn and ZnO,form p-n type heterojunctions,which make anthocyanin sensitized ZnO/P5FIn composite materials have better photoelectric activity compared to a single material.This is due to the absorption of visible light by anthocyanins and the effective energy level matching between zinc oxide and P5FIn,accelerating the transfer efficiency of photogenerated electrons in the material and effectively inhibiting the recombination of electron hole pairs,Thereby enhancing the photoelectric signal of the composite material.Quantum dots（QDs）are a new type of zero dimensional nanomaterials with excellent optical and physical properties,which have been widely used in the field of biomarkers and sensors.The introduction of B,N-QDs has the following effects;on the one hand,as an effective hole extractor,it enhances the carrier separation on the surface of anthocyanin sensitized ZnO/P5FIn heterojunction materials,reduces the efficiency of hole trapping,and enables the materials to provide more light energy;on the other hand,B,N-QDs bind to polydopamine（PDA）and antibodies（Ab2）,formed the second antibody marker PDA@B,N-QDs@Ab2 which further improves the sensitivity of the sensor.And based on PDA@B,N-QDs@Ab2,a sandwich type photoelectric chemical sensor with good detection performance has been constructed.The linear range of the sensor is 0.01-100 ng mL^-1,and the detection limit is 0.0033 ng mL^-1.In addition,the sensor has good selectivity,repeatability,and stability,providing a feasible method for the detection of tumor markers.