Regulation And Study Of Small Molecules On Molecularly Imprinted Electrochemistry Of Pyrrole Pathogenic Bacteria

Food safety is one of the issues of concern to people all over the world and has received widespread attention.Foodborne pathogenic bacteria cause serious diseases and social and economic losses in the world,so the molecular diagnosis of foodborne toxic pathogens at an early stage is crucial to prevent excessive damage.Electrochemical detection techniques are most suitable for the detection of foodborne pathogens because of their high sensitivity and fast detection speed.The recognition element of the sensor is also crucial.Traditionally,the recognition element is antigen-antibody recognition,and the antibody as a recognition receptor has disadvantages such as high cost and perishability and difficulty in coupling with the electrode.We use an"artificial antibody"molecularly imprinted polymer,which has a similar specific recognition function as the antibody,as the recognition element.Electrochemical sensors based on molecularly imprinted polymers are widely used for the detection of foodborne pathogens because of their simplicity and sensitivity.The matrix and structure of the sensing material are key factors in the performance of the sensor.Pyrrole,a popular conductive polymer monomeric substance,is a good candidate for the study of high-performance electrochemical sensors.Most studies on the synthesis of molecularly imprinted polymers based on polypyrrole use bulk imprinting or direct synthesis of molecularly imprinted polymers on the electrode surface,which typically yields low imprint cavity utilization and slow adsorption rates.The preparation of molecularly imprinted sensors for pathogenic bacteria using cyclic voltammetric electrochemical polymerization is cavity-free and improves the speed and efficiency of pathogen identification.Bacterially imprinted polymer sensors still face the challenges of difficult complete template removal,low affinity and poor sensitivity.To further improve their performance,it is crucial to control the morphology and modulate the chemistry of the imprinted polymers using doping engineering.The preparation of pyrrole molecularly imprinted electrochemical sensing by doped nanomaterials significantly improves the elution time of the template.However,due to the high price of nanomaterials,it is difficult to obtain them in commercial mass production.Therefore,this thesis uses the addition of small molecules doped with pyrrole molecules and pathogenic bacteria molecules to electrochemically prepare molecularly imprinted sensors to improve the performance of conventional pyrrole pathogenic bacteria sensors.Here we introduced D-tartaric acid（D-TA）as a dopant to construct D-TA/polypyrrole（PPy）-based bacteria imprinting polymer（DPBIP）sensor for sensitive and label-free detection of Vibrio parahaemolyticus（VP）.Polypyrrole can strongly bind with negatively charged cell surfaces through electrostatic interaction,and D-TA as a dopant can improve the conductivity of polypyrrole,D-tartaric acid can regulate the interaction between pyrrole and bacteria and provide certain active sites for the presence of pathogenic bacteria.It is demonstrated that D-TA doping can synergistically accelerate the removal of template bacteria from imprinted polymers（1.5 h）,improve bacteria affinity of imprinted sites（the recognition time of 30 min）,and enhance the sensitivity of DPBIP sensor(a detection limit of 19 CFU·m L^-1).The DPBIP sensor had a linear range of 10²～10⁶ CFU·m L^-1 and exhibited high selectivity and good repeatability.Moreover,a recovery of 94.8%～105.3%was achieved in drinking water and oyster samples.Therefore,functional small molecule doping opens a new avenue to engineering bacteria imprinting polymer sensors with high performance,holding potential applications in securing food safety.To further enhance the performance of the pathogenic bacteria sensor and reduce the elution time and identification time.In Chapter 3 we used the bifunctional monomers 3-aminophenyl boronic acid and pyrrole,Listeria monocytogenes as polymeric templates,using cyclic voltammetric electrochemical polymerization,followed by elution of the template bacteria using HAc/Me OH mixture（7:3,v/v）as eluent with an elution time of only 20 min.The prepared sensors were identified by oscillatory incubation with the template bacteria,using 3-amin The presence of the boronic acid group improves the adhesion to the pathogenic bacteria and greatly reduces the identification time to 20 min.The corrected linear equation is△R/R=10.437 Log10c-1.377 with a minimum detection limit of 1 CFU·m L^-1.The sensor showed good recoveries in drinking water and oyster samples.In addition,the sensor showed excellent reproducibility.The prepared sensor showed good stability with 100 cycles of cyclic voltammetric scanning.In the presence of several interfering bacteria,the sensor showed high specificity for the target bacteria.The sensor prepared by this method can be applied to the detection of other foodborne pathogenic bacteria,providing a promising test method for food detection technology.