Construction Of Photoelectrochemical Aptasensor And Its Application In Environmental Detection

In recent years,with the advancement of agriculture,aquaculture,and medicine,a considerable number of antibiotic pollutants have been released into the aquatic environment,causing environmental harm and endangering human health and safety.As a result,timely and sensitive detection of antibiotics in water is critical.Due to the benefits of quick reaction time,easy operation,no pretreatment,and low cost,photoelectrochemical analysis technology based on photoelectrochemical aptasensor has received a lot of attention in recent years.In light of this,integrating photoelectrochemical sensors with aptamer-specific identification technology improves the selectivity,sensitivity,and stability of detection.Here,two simple hydrothermal methods and in situ deposition techniques were used to create two three-dimensional heterojunction semiconductor materials with various polarity（three-dimensional flower-like CdSe@SnS₂and three-dimensional self-supporting Ag I@Ag/MIL-101（Cr））with different polarities were prepared by simple hydrothermal method and in situ deposition method as photoelectric conversion electrodes.The photoelectrochemical aptamer sensors for the detection of Sulfamethazine（SMZ）and Erythromycin（Ery）were constructed by aptamer as identification elements,which realized the sensitive detection of antibiotics in the aqueous environment.The research content and related results are as follows:（1）A"Ⅱ-type"high-efficiency photoelectrochemical（PEC）aptasensor based on three-dimensional flower-like CdSe@SnS₂nanocomposite has been developed to detect SMZ.The introduction of CdSe into SnS₂displayed an amplified PEC signal,which was higher than pure CdSe and SnS₂,attributable to its enhanced light harvesting capacity and promoted PEC energy conversion efficiency.Due to the formation of specific non-covalent bonds,SMZ-binding aptamer（SBA）has significant specificity and sensitivity.When SMZ was incubated on a CdSe@SnS2 modified electrode fixed with aminated SBA,the formation of the SMZ/SBA complex increased the space resistance of electron transfer and hindered the electronic migration between the electrodes,resulting in a decrease in photocurrent.The greater the adsorption amount on the SBA,the lower the photocurrent produced.After the condition optimization test,the photocurrent response of MCH/SBA/CdSe@SnS₂/FTO was inversely proportional to the SMZ concentration in the range of 0.1 p M to 100 p M,with a detection limit（3S/N）of 0.025 p M（at 0V vs.Hg/Hg Cl）.The recoveries ranged from95.8～104%with relative standard deviations（RSDs）?<?6.3%（n?=?3）in actual water sample.This PEC aptasensor which shows great potential in SMZ detection applications has high selectivity,reproducibility,and good stability.（2）The determination of Ery was investigated using a"Z-type"PEC aptasensor with Ag I@Ag/MIL-101（Cr）/FTO as the photocathode.This new method consists of three major components:（1）A three-dimensional self-supporting structure is successfully designed based on the morphological properties of MIL-101（Cr）and Ag I@Ag,which effectively improves the stability of the material load on the electrode surface,greatly improves the photoelectric conversion efficiency,and significantly amplifies the photocurrent.（2）The use of Ag I@Ag/MIL-101（Cr）/FTO in conjunction with aptamer recognition technology effectively ensures sensor selectivity and accuracy.（3）The photogenerated electron-hole pair separation was inhibited and the transport efficiency was improved by effectively constructing the photogenerated carrier transport mode between MIL-101（Cr）and Ag I@Ag.The transfer of photogenerated electrons and holes is hampered due to the inherent insulating properties of biological matrices,resulting in a decrease in the photocurrent signal.The cathodic detection limit（3S/N）of PEC aptasensor for Ery was 0.1 n M（0V vs.Hg/Hg Cl）under optimal conditions.1～150 n M is the linear range.When analyzing real samples,the developed PEC aptasensor demonstrates acceptable stability and sensitivity.The actual water sample recovered at a rate of 95.2%～107%,with a relative standard deviation（RSD）of 2.3～4.9%（n=3）.In the future,sensors built with PEC and aptamer technology may be able to detect antibiotics.Based on this,two three-dimensional heterojunction photoactive materials are designed to construct a new photoelectrochemical aptamer sensor with high sensitivity,high selectivity,high sensitivity,low cost and high sensitivity.Through the research of this project,it is expected to establish a new method for the detection of environmental pollutants.