Dual-Mode Fluorescent and Electrochemical Sensor with Dual-Emission Fluorescence Mediated by Host-Guest Interactions...

A dual-mode platform combining dual-emission fluorescence and electrochemical detection was developed for the isomer-selective sensing of p-nitrophenol (p-NP). Nitrogen-doped carbon quantum dots (N-CQDs) were functionalized with phosphate pillar[5]arene to produce P-CQDs, and host-guest assembly with acridine orange yielded P-CQDs@AO with dual emissions at 422 and 525 nm. p-NP selectively quenched both emissions, allowing fluorescence quantification over 0-60 μM with limits of detection of 0.265 μM (422 nm) and 0.476 μM (525 nm), while P-CQDs-modified electrodes enabled differential pulse voltammetric detection (10-200 μM, detection limit 3.58 μM). Tap water tests showed spiked recoveries of 97-103% with RSDs below 5% for both methods, confirming reliability for real-world applications. The orthogonal fluorescence/electrochemical readouts of the supramolecular host-guest-mediated dual-mode platform with improved selectivity among isomers enable accurate identification of p-NP.