Construction Of Ion-selective Electrode Detection System For Lysozyme And Calcium And Its Application In Food Analysis

In recent years,electrochemical sensors have been widely used in the detection and analysis of substances,due to their attractive features of rapid response,high specificity,high selectivity and easy to manipulate.Polymer membrane and all-solid ion-selective electrode are commonly used in electrochemical analysis and have been widely used in environmental detection,biomedical,food analysis and other fields.In this paper,ion-selective electrode was applied to the detection of lysozyme and Ca²⁺,and two different ion-selective electrode detection systems were constructed,which realized realize the specificity,rapid and sensitive detection of target substances.The main contents include the following aspects:1.A potentiometric sensing strategy was proposed with assembly of peptidoglycan/dopamine on a polycation-sensitive membrane electrode for measurement of lysozyme.The one-step codeposition strategy was used to realize the codeposition of polydopamine and peptidoglycan on the surface of polycation sensitive membrane.The peptidoglycan modified on the surface of the sensor can be selectively hydrolyzed by lysozyme,which allows the indicator ions enter the polymer membrane and causes the potential response.The lysozyme was quantitatively analyzed according to the potential change of protamine.The content of dopamine-peptidoglycan,incubation time and protamine concentration were optimized.Under the optimized conditions,the sensor shows a good linear relationship（R²=0.992）in the range of lysozyme concentration of1–10μg·m L^-1,and the detection limit was 0.6μg·m L^-1（3σ）,which could be used for the detection of lysozyme in actual samples.2.A portable screen printing Ca²⁺-ISE detection system was reported based on double signal amplification readout.An integrated screen printing selective electrode system for detecting calcium ions was established by using the screen printed electrode as the substrate.Ca²⁺-ISE deposited with conductive layer PEDOT-PSS was used as the working electrode,while the SPC-Zn as the reference electrode.A dual amplification readout strategy for electrical signals is proposed,in which multiple working electrodes are connected in parallel with conductive tape and the electrical signals are collected and released instantaneously by a capacitive element.A miniaturized and portable analytical detection system was constructed by using the electrode detection system and a multimeter,which is beneficial to the rapid in-situ detection of analytes.Under the optimized conditions,the current intensity of the system shows a good linear relationship with the activity of Ca²⁺in the range of 10^-2–10^-6mol·L^-1.The system was applied to the analysis of water samples,and the results are basically consistent with those obtained by the traditional Ca²⁺-ISE potential analysis.