| As a kind of important substance that regulates life activities,highly sensitive detection and analysis of signal molecules will contribute to reveal some rules in the life system,and thus have great significance for early detection and diagnosis of many human diseases.Therefore,there is an urgent need for getting a portable,fast,and specific detection method.Photoelectrochemistry?PEC?is a technology that brings photochemistry and electrochemistry together,which has the characteristics of low cost,easy operation and high sensitivity.The photoelectrochemical process refers to the active materials such as semiconductors and metals that cause electrons to be excited by absorption of photons under light conditions,causing carriers separation and charge transfer to form photocurrent,thereby achieving conversion between light energy and electric energy.At present,the application of wide band-gap semiconductor materials represented by SnO2 in the field of photoelectrochemistry is still a hot focus at home and abroad.This is because materials such as SnO2 and TiO2 exhibit excellent performance in photodegradation of organic pollutants,hydrogen production by photolysis of water,and photoelectrochemical sensors.However,SnO2 has a wide band gap?Eg=3.6 eV?and can only absorb about 5%of ultraviolet rays in sunlight,which greatly limits the utilization of solar energy.Another reason for limiting the widespread application of SnO2 is its strong recombination ability of photo-generated carriers,which shortens the lifetime of photo-generated electrons and reduces photoelectric conversion efficiency.In view of these problems,this subject sensitized SnO2 by kinds of methods such as electrodeposition,spin coating,and one-step synthesis,so that the constructed PEC sensor can directly use visible light.The simplest and most straightforward method is to modify them with precious metal nanoparticles and organic dye molecules,which speed up the carrier separation rate,increase the sensitivity of the PEC sensor and widen the application range.During the research,we explored a one-step synthesis method to optimize the stability of the composite materials.Ingenious sensing modes are also designed according to different disease-related markers,which improve the specificity and sensitivity of PEC biosensors.The specific work contents include the following three parts:1.A 3D network structure based on SnO2-AuNPs for PEC determination of NO2-in urineA three-dimensional?3D?network nanocomposite is constructed by electrospinning tin dioxide nanofibers?SnO2 NFs?on the surface of indium tin oxide?ITO?and then in-situ electrodepositing gold nanoparticles?AuNPs?.With the aid of large surface area of SnO2 NFs and the surface plasmon resonance?SPR?effect of AuNPs,the novel 3D architecture is beneficial to the mass transfer and the separation efficiency of photogenerated electrons and holes.In the presence of photosensitizer of Ru?bpy?32+(tris?2,2'-bipyridyl?dichlororuthenium?II?hexahydrate?Ru?bpy?3?PF6?2?,the ITO/SnO2-AuNPs electrode shows good photoelectrochemical?PEC?response to nitrite?NO2-?under visible light irradiation.The linear range for NO2-determination is from 10-99 to 10-55 mol·L-11 with a low detection limit?LOD?of 4.8×10-1010 mol·L-1.The ITO/SnO2-AuNPs photoanode based PEC sensor is also successfully applied to analyze trace NO2-in human urine,showing excellent anti-interference and stability.This work may pave the way for designing noble metal-semiconductor heterogeneous materials with tailored properties for the field of biosensor design.2.One-step synthesis of SnO2@AuNPs for detection of calprotectin,a marker related to inflammatory bowel diseaseThis work synthesizes metal-semiconductor heterogeneous materials?SnO2@AuNPs?in one step,which has high photoelectric conversion efficiency and shows good photoelectric performance.AuNPs-sensitized SnO2 semiconductor not only broaden the material's absorption range for visible light,increase the light absorption intensity,but also easily form Schottky barrier at heterogeneous interface,effectively promoting the separation of photogenerated electrons and holes.Based on the uniform and strong characteristics of this composite,the identification layer can be modified on its surface.Alkaline phosphatase?ALP?can be used as a signal label to catalyze L-ascorbic acid-2-phosphate trisodium salt?AAP?,resulting in Ascorbic acid?AA?used as a donor.As the amount of Calprotectin?CP?increases,the photocurrent increases.The dual-antibody sandwich-structure“signal-on”biosensor is skillfully constructed to improve the specificity of photoelectrochemical detection.This sensor has been successfully used for the analysis and determination of CP,a marker related to trace inflammatory bowel disease.The linear range is 0.01-20?g·mL-1,the detection limit is as low as 3.2 ng·mL-1,and the specificity and stability are good.The detection of CP in actual samples?blood sample?has also obtained the expected recovery rate.3.Preparation of new SnO2@PtNPs material and development of PEC sensor for detecting endocrine disruptor BPSAt present,bisphenol S?BPS?,as a substitute for restricted bisphenol A?BPA?,is widely used in the production of plastic products such as baby bottles,plastic wrap,and food packaging.However,due to the similar chemical structure between the two,BPS retains similar estrogen activity and can disrupt the human immune system and reproductive system.This work,we synthesized a new hybrid material SnO2@PtNPs using the one-step method explored in Work 2,and found that its photoelectric conversion efficiency was higher than SnO2@AuNPs.And the BPS was dried on the electrode surface and enriched,which further improves the sensitivity of the sensor.The photoelectrochemical?PEC?,electrochemical impedance spectroscopy?EIS?,solid ultraviolet diffuse reflectance?UV-vis diffuse?,and fluorescence spectrum?PL?methods were used to characterize the construction process of the sensor and its performance.Experimental results show that the PEC response of the sensor to BPS is linear in concentration range of 10-7-10-33 mol·L-1,with LOD of 0.047?mol·L-1,and the sensor has good selectivity and stability. |
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