A Micro CE Chip for In-column Urea/Urease Reaction and Electrochemical Detection Utilizing Integrated Gold Nanoelectrode Ensemble (GNEE)

This paper proposes an innovative PMMA-based microchip with an integrated gold nanoelectrode ensemble (GNEE) for the electrochemical detection of in-column urea/urease reactions. The GNEE is fabricated using an electrodeless deposition process on a thin polycarbonate (PC) film and bonded directly onto a PMMA substrate to carry out high performance electrochemical detections. A low- temperature azeotropic solvent bonding process is utilized to seal the microfluidic channels with a high bonding quality. The experimental results show that the GNEE electrode provides a larger CV window for ammonia than a conventional planar gold electrode due to electro-catalytic effects. The in-column bioanalytical reaction of urea/urease is successfully demonstrated. The detection results demonstrate a satisfactory coefficient (R2 value) and high reproducibility with a detection limit of 14.8 muM when applied to the detection of NH4+, the product of the urea/urease biocatalytic reaction. These results confirm the capability of the proposed device for the high-resolution CE-EC detection of bioanalytical reactions.