Studies On All-solid-state Potentiometric Sensor Based On Peptide Recognition In Bacterial Detection

Bacterial infection has caused many problems closely related to human life,such as food safety,water pollution and so on.Rapid,sensitive and accurate bacterial detection,especially distinguishing different bacterial species in mixed samples,is essential to guide the treatment of bacterial infections.Currently,sensors based on different recognition mechanisms have been developed for bacterial recognition based on differences in physical and chemical properties caused by different surface structures of bacteria and differences in metabolites that can be targeted.Nuclear magnetic resonance(NMR)and chromatographic separation techniques combined with mass spectrometry(MS)methods have been used to identify bacteria,but they require expensive equipment and specialized operations.Optical diagnostic platforms for pathogenic bacteria are emerging,providing highly sensitive detection tools for clinical or immediate diagnosis.As most optical sensors are susceptible to interference from the detection environment,the detection capability is reduced.All-solid-state potentiometric sensing technology has developed rapidly in recent years due to its advantages of low energy consumption,low cost and easy array.Peptides have the advantages of being more stable in harsh environment and suitable for large-scale production,and have been widely used in the recognition and detection of various target objects,such as ions,molecules,proteins,bacteria and cells.Peptides can be attached to bacteria through electrostatic and hydrophobic interactions.Based on this principle,biosensors for bacterial determination have been developed.In this paper,we developed an all-solid-state potentiometric sensor based on peptide recognition to realize quantitative detection of Staphylococcus aureus.At the same time,through the introduction of internal calibration system,a self-calibrating potential sensor array was developed to realize the simultaneous detection of E.coli O157:H7 and Staphylococcus aureus.The concrete content are as follows:Chapter One:IntroductionThis chapter first introduces the significance of bacteria detection and identification strategy;Then,the application of different new recognition molecules,especially peptides in bacterial detection is introduced.Finally,the research progress of fluorescence,surface-enhanced raman spectroscopy and surface plasmon resonance technology in bacterial detection was introduced,and the principle and application of all-solid-state potentiometric sensing technology were emphasized.Chapter Two:Determination of Staphylococcus aureus by all-solid-state Potentiometric biosensor based on peptide recognitionIn this chapter,a novel all-solid-state potentiometric sensor based on peptide recognition is developed for the detection of Staphylococcus aureus.First,the electrode surface was modified with a dendritic gold nanostructured material(DenAu)to increase the effective area and response stability of the electrode.Then,the positively charged peptides interacts with the negatively charged carboxyl group in anionic conducting polymer polythiophene 3-acetate(PTAA)and is self-assembled and modified on the electrode to prepare an all-solid-state potentiometric sensor.As the peptides can specifically recognize S.aureus and cause conformational change,the effective charge number on the electrode surface changes,resulting in the corresponding potential response.Under optimal conditions,the sensor showed a linear response to S.aureus in the concentration range of 1.0×10~2CFU/mL-1.0×10~6CFU/mL,and the detection limit was 20 CFU/mL.The excellent reliability and reproducibility demonstrated by the sensor developed in this study creates an effective approach for bacterial monitoring.Chapter Three:Simultaneous detection of Staphylococcus aureus and Escherichia coli O157:H7 using the self-calibrated potentiometric sensors arrayIn this chapter,we develop a new self-calibrating potentiometric sensor array based on a 4-channel screen-printed carbon electrode,which includes two sensing channels modified with specific peptides for simultaneous detection of Staphylococcus aureus and Escherichia coli O157:H7,and two calibration channels modified with a scrambled peptide to eliminate the influence of background substrate on detection,which improve the accuracy of detection.The results showed that under optimal conditions,the sensor array can effective identify Staphylococcus aureus and Escherichia coli O157:the detection limits were 38 CFU/mL and 241 CFU/mL,and the linear response ranges were 1.0×10~2-1.0×10~6CFU/mL and 1.0×10~3-1.0×10~5CFU/mL,respectively,with high specificity.The sensor array was used to detect Staphylococcus aureus and Escherichia coli O157:H7 in milk,which provided an effective way for simultaneous detection of multiple objects in actual samples.