Construction Of Self-powered Aptasensors Based On Bismuth-based Composite Photocatalysts

As an emerging analytical technique,the self-powered sensor based on a photocatalytic fuel cell（PFC）combines the advantages of photocatalysis and electroanalysis.The sensing process requires no external energy,which is conducive to the miniaturization and portable development of sensors.Hence,the self-powered sensing strategies have been used in biological analysis,environmental monitoring,food safety and other fields.In this thesis,the PFC was constructed by preparing bismuth-based photocatalytic materials and combined with nucleic acid aptamers that possess the function of specific selection,to achieve the self-powered detection of antibiotics in environment.In addition,a capacitor and a digital multimeter（DMM）were introduced in the sensing strategy to further improve the sensitivity of the self-powered detection method.The main research contents of this paper were shown below:（Ⅰ）.BiVO₄ was prepared by a simple solid-liquid reaction and doped with a certain amount of graphene to modify the photoelectrode as photocatalytic materials.The PFC was constructed by the graphene-Bi VO₄（G-Bi VO₄）photoanode and the Pt cathode,and the reaction of the PFC was based on the water-oxygen cycle.In order to improve the selectivity of the PFC sensor,kanamycin（KAN）aptamer was modified on the surface of the photoanode.Under optimal conditions,the maximum power density of the PFC has a linear relationship with the logarithm of the KAN solution concentration.The quantitative detection of KAN ranges from 10 n M to 500 n M,and the detection limit was 1.0 n M（S/N=3）.The self-powered sensing strategy exhibited good stability,selectivity,reproducibility,and can be applied to the determination of real samples.（Ⅱ）.To improve the sensitivity of self-powered sensor,a self-powered sensing strategy based on PFC/capacitor hybrid device was proposed for sensitive detection of streptomycin（STR）.The PFC was constructed with graphene-Bi₂WO₆（G-Bi₂WO₆）photoanode and Pt cathode,which was realized by the photocatalytic oxidation of ascorbic acid and the electrocatalytic reduction of oxygen.After modifying the aptamer of STR on the photoanode,the output performance of the PFC was declined with the increased STR concentration.In addition,the capacitor was charged by the PFC to accumulate the electric energy of the PFC.And then,the charged capacitor released the accumulated energy through the short circuit instantly,and the amplified electric signal was read by DMM.This signal was found to sensitively respond to STR concentration range from 0.2 n M to 200 n M,and the detection limit was 0.06 n M（S/N=3）.Moreover,the sensitivity was enhanced 8.7-fold compared to that without the amplification of capacitor.