Cell Imprinted Polymers Integrated with Microfluidic Biosensors for Electrical and Electrochemical Detection of Bacteria in Water.

There is a growing demand for sensors that enable rapid, cost-effective, and laboratory-free detection of microorganisms in clinical, food and environmental samples. Traditional methods are slow, expensive, and require specialized personnel. Biosensors offer a promising alternative but face challenges like instability, high cost, short lifespan, and complex synthesis of the biorecognition elements. Molecularly imprinted polymers (MIPs) provide a more robust, cost-effective solution by embedding the target analyte's imprint into a polymer matrix. While MIPs are effective for small molecules, designing them for biological cells is more complex due to their structural diversity. Noncovalent interactions, preferred in synthesizing cell-imprinted polymers (CIPs), enable easier binding and dissociation. Selecting suitable functional monomers is crucial, as their interactions with cell surface molecules determine imprinting success. However, the effects of CIP composition on the bacterial capture efficiency remain unexplored. Furthermore, integrating CIPs into microfluidic and electrochemical sensing platforms is vital for portable, real-time detection systems.

This research aimed to improve the understanding of the CIPs’ effectiveness in capturing bacteria to develop effective bacteria-sensing platforms using microfluidic devices. In Objective 1, we optimized a polymerization methodology for uniform functionalization of stainless steel microwires reproducible CIP coatings, imprinted with E. coli as the template. In Objective 2, we assessed E. coli rebinding performance which demonstrated 76±5 % uptake efficiency with the optimized composition. In Objective 3, we integrated CIPs into a conductometric-based microfluidic sensor. Resistance changes normalization and subsequent analysis of the dose-response curve revealed a dynamic range of 10^4 to 10^7 CFU/mL, with a limit of detection (LOD) of 2.1×10^5 CFU/mL. Specificity experiments demonstrated the specificity of the sensor towards imprinted E. coli cells. Further improvements were made by modifying the sensor design to a three-electrode configuration and employing electrochemical impedance spectroscopy (EIS). The charge-transfer resistance changes normalization and the subsequent analysis revealed an enhanced LOD of 2× 10^2 CFU/mL, with a broader dynamic range of 10^2 to 10^7 CFU/mL. The proposed sensor has the potential to offer a cost-effective, durable, portable, and real-time solution for the detection of waterborne pathogens. Future impacts include enhancing bacterial detection in environmental monitoring, food safety, and healthcare.