The Construction And Applications Of Near Infrared Responsive Photoelectrochemical Sensor Based On Defectengineered TiO₂ Electrode Arrays

Photoelectrochemical?PEC?sensing is a novel analytical technique for biomolecules? detection.Stemming from optical and electrochemical detection techniques with unique signal conversion model,the PEC sensing has implemented sensitive detection of target molecules,in addition,after coupling with the specific biological recognition units,the PEC sensing also achieved selective detection.Compared with optical and electrochemical detections,the PEC analysis not only has presented convenient readout model,easy miniaturization,but also has showed low background noise and high sensitivity.Therefore,the PEC analysis has achieved great development in the field of biological and environmental analysis due to its desirable advantages and economic potential for biomolecule detection.In recent years,most efforts in PEC analysis have been made with ultraviolet and visible light?UV-Vis?as light source.However,this is not the perfect choice because the high energy of UV-Vis light is detrimental to biomolecules,and its short penetration depth limits its detection activity to the top surface of the organism.In contrast,near-infrared?NIR?light is a superior option with better biocompatibility and deeper penetration depth for biological tissues.The NIR light have been successfully employed to induce in vivo photothermal therapy,to control drug release at a specific time and location,and to probe analytes through NIR fluorescent images.Therefore,NIR PEC analysis will be a powerful tool for biomolecule detection and is expected to obtain abundant detection information in biological analysis.However,to the best of our knowledge,very surprisingly,NIR PEC analysis works are rarely published.After careful deliberation,we believe that can be ascribed to the scarcity of stable and proper photoelectrode materials in NIR region.Therefore,the exploration of desirable NIR-responsive photoelectrode materials is still a big challenge.In this paper,three NIR-responsive PEC sensors were designed based on TiO₂ nanoarrays,and implemented sensitive detection of dopamine molecules and antibiotictetracycline.Chapter 1.IntroductionIn this chapter,we first introduce the mechanism of PEC sensor and corresponding recent researches,and then introduce the advantages,properties and appilcations of TiO₂ nanoarrays and NIR photoelectric materials.At the end of this chapter,we highlight the purpose and significance of our researches.Chapter 2.Defect-engineered TiO₂ nanoarrays electrode achieved highly sensitive detection of dopamine under near-infrared illuminationIn this work,the defect-engineered TiO₂ nanoarrays electrode was modified to realize NIR light absorption and implemented highly sensitive detection of dopamine molecules.The TiO₂ nanoarrays electrode with top-photonic crystal layer was prepared by an anodization method with high-purity Ti foil as based material.The TiO₂ nanoarrays were annealed in a sealed glass tube with high-vacuum to obtained the defect-engineered NIR responsive photoelectrodes.Finally,through the unique covalent bonds between dopamine and TiO₂,the selective detection of dopamine was as well as realized.Chapter 3.NIR PEC detection of dopamine based on phosphorus doped defect-engineered TiO₂ nanoarray electrodesIn this study,we fabricated phosphorus doped defect-engineered TiO₂ nanoarrays,which presented high NIR response.The TiO₂ nanoarray electrodes with top-photonic crystal layer were prepared by a two-step anodization method,then the electrode was sealed in a glass-tube with an appropriate amount of Na HPO2 in high-vacuum.After annealing with high temperature,the phosphorus was doped into the lattice of TiO₂ and the defect of oxygen vacancies were also formed.The fabricated materials were utilized to assemble NIR responsive PEC sensors and implemented sensitive and selective detection of dopamine molecules.Chapter 4.Construction of NIR PEC sensor based on gold nanoparticles modified defect-engineered TiO₂ photonic crystal materialsIn this work,the gold nanoparticles with surface plasmonic resonance were modified on the surface of defect-engineered TiO₂ photonic crystal,and presented NIR PEC response.The gold nanoparticles were decorated onto the TiO₂ with an ion sputtering method,which not only guaranteed uniform distribution of gold nanoparticles,but also produced further oxygen vacancies in TiO₂.Furthermore,with the help of unique Au-S bond,the aptamers were covalently connected with the gold nanoparticles,and implemented sensitive and selective detection of tetracyclines.