Enzyme-doped polyester thread coated with PVC membrane for on-site urea and glucose detection on a thread-based microfluidic system

This study presents a novel method to produce enzyme-doped thread with polyvinylchloride (PVC) membrane coating for on-site urea and glucose detection. The enzyme can be directly applied on the thread without delicate pretreatment or surface modification process. The passing biomolecules are digested by the enzymes and then electrochemically detected downstream. With this approach, liquid transportation, biocatalytic reaction and CE-EC detection of biosamples can be simply achieved on a low-cost thread device. The thin PVC membrane on the enzyme-doped thread can further prevent from the rapid evaporation of the running buffer caused by Joule heat during CE separation. Results show that the PVC coated thread can be operated at a higher separation electric field of 500 V/cm. Successful on-site enzyme digestion, CE separation and EC detection of urea and glucose samples in a single test run is demonstrated. The measured results also indicate that the developed system exhibits good linear dynamic range for detecting urea and glucose samples with the concentration of 0.1 mM~10.0 mM (R²=0.9850) and 0.1 mM~13.0 mM (R²= 0.9668), which is suitable for detecting blood urea nitrogen (1.78~7.12 mM) and glucose in serum (3.89~6.11 mM).