Using personal uric acid meter and enzyme-DNA conjugate for portable and quantitative DNA detection

A simple and distinctive assay for quantitating target DNA was developed based on personal uric acid meter (PUAM) and xanthine oxidase modified DNA (xanthine oxidase-DNA). Capture DNA was assembled on the Au film by the formation of AuS bond. When target DNA was added, it was complementary to capture DNA at one-half of the segment and complementary to the xanthine oxidase-DNA at the other half-segment, resulting in the formation of a stable duplex complex. As a result, the xanthine oxidase was dragged to the Au film. Since xanthine oxidase could catalyze hydrolysis of xanthine to uric acid, the concentration of target DNA in the sample could be quantified by monitoring uric acid using PUAM. Since the signal was amplified based on the enzymatic turnovers, this enzyme-based assay made it possible that 10 pM p53 DNA or 4 pM HBV DNA could be detected using PUAM. This assay also showed excellent selectivity toward mismatches, and demonstrated its applicability for the target detection in human serum. Furthermore, this protocol showed a new strategy to detect non-uric acid targets using PUAM.