| Since the outbreak of COVID-19,COVID-19 has brought a serious threat to global public health.Therefore,people are paying more and more attention to biological related detection and research,including:（based drugs,salts;viruses,bacteria;markers,mirco RNA,etc.）.Two-dimensional materials with unique properties are ideal materials for constructing a new generation of biosensors.Two-dimensional materials have good electrochemical activity,large specific surface area and biocompatibility.Its special structure can make the deposition orientation of biological molecules such as proteins more free,effectively avoid the aggregation of biological molecules,and maximize the biological activity and stability of proteins.Electrochemical biosensors constructed from two-dimensional materials have become a research hotspot in the fields of material chemistry,electronic science and life science.In addition,introducing two-dimensional materials into the electrode interface will accelerate charge transfer,promote redox reaction and enhance the interaction between protein and substrate.This thesis makes full use of the unique properties of two-dimensional materials and their composites to design and prepare a variety of two-dimensional composite materials and their use in modifying electrodes to achieve the detection of nitrite,influenza virus H9N2,and liver cancer marker PIVKA-II.The specific research contents include the following three parts:（1）Spherical Co VO was synthesized by secondary hydrothermal method using cobalt nitrate,urea,ammonium fluoride and sodium vanadate as raw materials,The sea urchin-like Co VO/Ti2C3Tx composite was synthesized by electrostatic self-assembly with the etched two-dimensional Ti2C3Tx MXene and made into an electrochemical nitrite sensor.The results show that the sensor has a wide linear range of 0.5–2000μM)with detection limit is 0.1μM.It also has good selectivity and stability.In addition,its good electrocatalytic activity was investigated by first-principles calculation,and the calculation results were consistent with the experiment.The sensor was evaluated with actual samples（milk and drinking water）and also showed good detection effect.Finally,the sensing mechanism was analyzed by X-ray photoelectron spectroscopy（XPS）of the materials before and after the reaction.（2）Two-dimensional Sn S2 nanocrystals were grown on fluorine-doped Sn O2conductive glass（FTO）by chemical vapor deposition（CVD）,and then the Sn S2/Ag2S heterojunction was prepared by chemical bath deposition（CBD）.Using thioglycolic acid（TAA）for functionalization and EDC/NHS activation,H9N2 antibody was covalently linked to Sn S2/Ag2S heterojunction to construct a photoelectric chemical sensor for influenza virus H9N2.At the same time,a series of experiments were carried out to explore the growth conditions of Sn S2.Under the optimal conditions,the influenza virus sensor based on Sn S2/Ag2S heterojunction can detect H9N2 in the range of 500 fg/m L–10 ng/m L,and the detection limit is as low as 80 fg/m L.The sensor also has excellent H9N2 specificity.（3）In order to further explore the application of bioelectrochemical sensing in human health monitoring,based on the previous research work,an integrated microfluidic photoelectrochemical sensor based on Sn S2/Zn In2S4 heterojunction is proposed in this study for the detection of abnormal prothrombin（PIVKA-II）,a marker of liver cancer.In the experiment,the Sn S2/Zn In2S4 heterojunction prepared by the secondary hydrothermal method was used as the active material,and the microfluidic photoelectrochemical sensor was prepared by laser etching,photolithography and other techniques.The X-ray diffraction analysis of the Sn S2/Zn In2S4 sensitive material was carried out,and the X-ray photoelectron spectroscopy proved that the material was successfully prepared.Under the optimal conditions,the PIVKA-II sensitive response test proved that the sensor can achieve accurate and reliable quantitative detection of liver cancer marker PIVKA-II in the range of 0.1pg/m L-500 ng/m L.It is worth mentioning that this method integrates two-dimensional materials,electrodes and reaction channels on FTO,providing a new detection idea. |
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