Rapid detection of apparent amylose in rice using microfluidic paper-based analytical devices based on Ce-UiO66 with high oxidase-like activity.

Apparent amylose content is a key determinant of rice flavor quality, yet traditional detection methods are often costly and time-consuming. To address this, we developed Ce-UiO66 nanozyme-based microfluidic paper-based analytical devices (μPADs) for the rapid quantification of apparent amylose. The sensing mechanism relies on the formation of a blue-purple apparent amylose-iodine complex via in situ catalytic oxidation, which is quantified through smartphone-based grayscale analysis. Mechanistic studies reveal that the catalytic activity of Ce-UiO66 is driven by O2- and H2O2 intermediates. The tri-zonal design of the μPADs (droplet, reaction, and detection zones) effectively minimizes in situ reaction interference. Under optimized conditions, the method achieved a linear range of 0-40% within 15 min, showing excellent agreement with flow injection analysis. This Ce-UiO66@μPAD platform demonstrates significant potential as a low-cost, portable tool for rapid monitoring of apparent amylose in rice.