Fabrication of a polycarbonate microdevice and boronic acid-mediated surface modification for on-chip sample purification and amplification of foodborne pathogens

In this study, we integrated sample purification and genetic amplification in a seamless polycarbonate microdevice to facilitate foodborne pathogen detection. The sample purification process was realized based on the increased affinity of the boronic acid-modified surface toward the cis -diol group present on the bacterial outer membrane. The modification procedure was conducted at room temperature using disposable syringe. The visible color and fluorescence signals of alizarin red sodium were used to confirm the success of the surface modification process. Escherichia coli O157:H7 containing green fluorescence protein (GFP) and Staphylococcus aureus were chosen as the microbial models to demonstrate the nonspecific immobilization using the microdevice. Bacterial solutions of various concentrations were injected into the microdevice at three flow rates to optimize the operation conditions. This microdevice successfully amplified the 384-bp fragment of the eae A gene of the captured E. coli O157:H7 within 1 h. Its detection limit for E. coli O157:H7 was determined to be 1 × 10 3 colony-forming units per milliliter (CFU mL −1 ). The proposed microdevice serves as a monolithic platform for facile and on-site identification of major foodborne pathogens.