Advanced characterization in molecularly imprinted Polypyrrole for potentiometric lactose sensing

Abstract

The motivation behind this study comes from the necessity to monitor lactose levels in milk for quality control and public health, as existing methods are often complex, time-consuming, and expensive. This research aims to develop a specific and sensitive potentiometric sensor for lactose detection using electropolymerised polypyrrole- based molecularly imprinted polymers (MIPs). MIP sensors were developed through chronoamperometric elec- tropolymerisation of pyrrole in the presence of lactose, creating specific binding sites. Raman spectroscopy, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM) were used to assess surface morphology confirming the presence of imprinted cavities and surface changes after lactose removal. The electrochemical performance of the sensors was evaluated by EIS spectroscopy demonstrating the influence of MIP cavities on the electron transfer of the sensor compared to non-imprinted polymer (NIP). Finally, open circuit potentials (OCP) in various lactose concentrations and real milk samples confirmed the high sensitivity and selectivity of the MIP sensors. Moreover, Principal Component Analysis (PCA), Partial Least Square Regression (PLS), and Support Vector Machine (SVM) models were satisfactorily employed to establish corre- lations between OCP measurements and lactose content, allowing its prediction in milk samples with an average error of 6 %. The results demonstrated that the MIP sensors exhibited high selectivity and sensitivity towards lactose, with improved responses compared to NIP sensors. The study concludes that polypyrrole-based MIPs provide a robust and effective approach for lactose detection and prediction in dairy products, offering a promising tool for quality control and ensuring consumer safety