A Hand-held Electrochemical Biosensor with Glucose Oxidase-Polydopamine Based Polymeric Nanocomposites and Prussian Blue Modified Screen-printed Interdigitated Microelectrodes for the Detection of E. coli O157:H7 in Foods

Introduction: The possible presence of pathogenic bacteria in foods has always been a great threat to the wellbeing of people and the revenue of food manufactures. Therefore, the demanding for advanced detection methods that can rapidly and sensitively detect these pathogens using a portable device for on-line or in-field applications has been of great importance.

Purpose: In this study, a handheld electrochemical biosensor for the detection of E. coli O157:H7 was developed with the integration of glucose oxidase (GOx)-polydopamine (PDA) based polymeric nanocomposites (PMNCs) for carrying and labeling the target bacteria and Prussian blue (PB) modified screen-printed interdigitated microelectrodes (SP-IDMEs) for electrochemical measurement. 

Methods: The PMNCs consisting of MBs and abundant GOx in the matrix of PDA were first synthesized by the self-polymerization of dopamine (DA) under alkaline condition. Gold nanoparticles (AuNPs) were immobilized on the surface of PDA-GOx-MBs PMNCs through biochemical synthesis to achieve further high efficient adsorption of antibodies (Abs) and GOx. The final product of Abs/GOx_out/GOx-MBs@PDA PMNCs was used to capture target bacteria and separate them from food matrix. The PMNCs-cells conjugates were then filtered through a filter paper, and the free PMNCs were collected after filtration. The collected PMNCs were transferred into glucose solution to allow the enzymatic reaction. The amperometric detection can be measured with a handheld electrochemical detector using PB-modified SP-IDME.

Results: The constructed biosensor had been proved to be able to detect E. coli O157:H7 in pure culture and the detection limit was achieved about10² CFU/ml. Ongoing research has focused on the validation of the biosensor with food sample like ground beef.

Significance: The developed biosensor exhibited high load of enzyme through PMNCs for efficient amplification of signals and applied a portable device for easy and rapid measurement in detection of foodborne pathogens.