PVDF-based molecularly imprinted ratiometric fluorescent test paper with improved visualization effect for catechol monitoring

Various methods have been proposed for the determination of catechol (CT), however, the actual applications of these methods were restricted by instrument dependence, complex operations and difficulty of the on-site monitoring. In this work, a molecularly imprinted ratiometric fluorescent test paper based on hydrophobic polyvinylidene difluoride (PVDF) membrane was successfully prepared for facile and on-site monitoring of CT. Firstly, a uniform core–shell molecularly imprinted ratiometric fluorescence sensor ([email protected]2@Si QDs-MIPs) was successfully synthesized. Then the test paper was fabricated by facilely coating [email protected]2@Si QDs-MIPs on a PVDF membrane by the vacuum filtration method. Ultimately, under optimal conditions, [email protected]2@Si QDs-MIPs exhibited excellent stability and a relatively lower limit of detection (LOD) of 0.11 μM, satisfied recovery rates of 97.73%-102.30% and relative standard deviations of 2.01%-2.34%. Moreover, the selective study and ions inference experiment synergistically proved that the polymer has good anti-interference ability. Afterwards, the PVDF membrane was eventually selected to be the optimal substrate due to the uniform distribution of fluorescent substances on its surface, thus, greatly improved the accuracy of detection. The resultant test paper hugely improved the practicability and provided a reference for water quality testing. The facile and efficient strategy reported here opens a window for the rapid, visual and on-site detection of CT in river water samples.