Construction Of Molecularly Imprinted Sensors Based On Titanium Dioxide And Composites And Their Applications In The Detection Of Salicylic Acid

Salicylic acid(SA)is the raw material of in a great many analgesics and anti-inflammatory drugs.It is the main component of most pain and antipyretic drugs.Abuse of SA would result in side effects to the health of human beings,and can cause poisoning symptoms,such as nausea,dizziness,tinnitus,diarrhea and mental problems,and even endanger life.Therefore,developing a new method for SA detection is necessary.In recent years,molecularly imprinted electrochemical and photoelectrochemical sensors have been widely used in analysis and detection due to their simple equipment,easy operation,high chemical stability and high sensitivity.Titanium dioxide(TiO2),as a traditional semiconductor nanomaterial,has always attracted the interest of scientific researchers,but its shortcomings such as large band gap and poor conductivity lead to low sensitivity and limit its application in the field of biosensors.Therefore,TiO2 nanomaterials have been improved by methods such as material recombination to enhance the performance of the sensor and improve the responsiveness of photoelectrochemistry.In this paper,a hydrothermal method is used to prepare functionalized TiO2 nanomaterials and composite nanomaterials,which are used to construct electrochemical and photoelectrochemical sensors for for the identification and detection of salicylic acid.The main contents are as followsPart One Construction of electrochemical sensor based on situ grown TiO2 NRAs by molecularly imprinted polymers for SA recognitionTitanium dioxide nanorods(TiO2 NRAs)were successfully grown in situ on the surface of fluorine-doped tin oxide glass(FTO)by a one-step hydrothermal reaction.Using salicylic acid(SA)as the template molecule,methacrylic acid(MAA)as the functional monomer,andazodiisobutyronitrile(AIBN)as the initiator,the MIPs imprinted film was formed on the surface of TiO2 NRAs@FTO by UV-initiated polymerization to construct MIPs/TiO2 NRAs@FTO electrochemical sensors.The MIPs/TiO2 NRAs@FTO electrode was studied by scanning electron microscopy(SEM)and other characterization methods.Under optimized conditions,the linear range of the differential pulse voltammetry(DPV)signal of the MIPs/TiO2 NRAs@FTO electrochemical sensor for the detection of SA was 1.0×10-7 to 5.0×10-5 mol·L-1.The detection limit was down to 3.9×10-8 mol·L-1.The results show that the MIPs/TiO2 NRAs@FTO electrochemical sensor is easy to construct and has been successfully applied to the detection of SA in aspirin tabletsPart Two Construction of photoelectrochemical sensor based on Sn3O4@TiO2@CFP by molecularly imprinted polymers for salicylic acid recognition and detectionBy a two-step hydrothermal synthesis method,firstly,TiO2 nanorods were grown in situ on carbon paper fibers(CFP),and then Sn3O4 nanosheets were successfully loaded on TiO2 nanorods.Using SA as the template molecule,MAA as the functional monomer,and 2,4-diethylthioxanthene-9-one as the photoinitiator,polymerization was initiated by ultraviolet light to prepare molecularly imprinted polymer film of salicylic acid on the surface of Sn3O4@TiO2@CFP to construct MIPs/Sn3O4@TiO2@CFP photoelectrochemical sensors.The MIPs/Sn3O4@TiO2@CFP electrode was characterized by SEM,XRD,DPV and EIS.The sensor can realize the sensitive determination of salicylic acid under the excitation of light.Under optimal conditions,the response signal of the MIPs/Sn3O4@TiO2@CFP photoelectrochemical sensor for the detection of salicylic acid molecules increases significantly,and the linear range of the sensor for the detection of SA was 1.0×10-10-1.0×10-5 mol·L-1,the detection limit was down to 3.21×10-11 mol·L-1.Experiments have proved that the MIPs/Sn3O4@TiO2@CFP photoelectrochemical sensor has high stability,high sensitivity and high selectivity,and can be successfully applied to the detection of salicylic acid in real samples.Part Three Construction of photoelectrochemical sensor based on Cu-MOFs@TiO2@FTO by molecularly imprinted polymers for salicylic acid recognition and detectionBy a simple two-step hydrothermal synthesis method,Cu-MOFs material was loaded on the surface of the TiO2@FTO electrode to form Cu-MOFs@TiO2 composite materials.Using SA as the template molecule,MAA as the functional monomer,and 2,4-diethylthioxanthene-9-one as the photoinitiator,polymerization was initiated on the surface of Cu-MOFs@TiO2@FTO by ultraviolet light to form a molecularly imprinted film.Then MIPs/Cu-MOFs@TiO2@FTO photoelectrochemical sensor was constructed and used for the detection of salicylic acid molecules.The MIPs/Cu-MOFs@TiO2@FTO electrode was characterized by SEM,XRD,DPV,and EIS.Due to the large specific surface area of the Cu-MOFs@TiO2 composite material and good visible light response of Cu-MOFs,the photocurrent response of the MIPs/Cu-MOFs@TiO2@FTO photoelectrochemical sensor was significantly enhanced.The linear detection range of the photoelectrochemical sensor for salicylic acid was 1.0×10-11-1.0×10-5 mol·L-1,and the detection limit was as low as 2.98×10-12 mol·L-1.The results show that the PEC sensor based on MIPs/Cu-MOFs@TiO2@FTO can establish the detection of salicylic acid,and demonstrat the excellent stability,sensitivity and selectivity.