Fluorescent-SERS dual-mode strategy combined with mussel-inspired molecularly imprinted polymers for ultrasensitivity and high selectivity detection of 4-Nitrophenol

A novel surface molecularly imprinted polymers-based dual-mode nanoprobe, NH₂-MIL-53(Al)@PDA-MIPs/AuNPs, was developed for fluorescence (FL) and surface-enhanced Raman scattering (SERS) detection of 4-Nitrophenol (4-NP) in real water samples. By integrating the advantage of rapid visual detection in FL mode with the advantage of ultrasensitive sensing in SERS mode, the FL-SERS dual-modal approach offers cross-verification of results and extends the detection range. The incorporation of NH₂-MIL-53(Al) as carriers not only improved the MIPs stability and prevented the deformation of the imprinting cavity, but also provided stable emission signals, eliminating the need for complex fluorescence sources preparation. The PDA-based MIPs layer isolated NH₂-MIL-53(Al) from the external interferences, providing selective cavities for improved specificity. Additionally, the functional groups on the surface of PDA-based MIPs facilitated the in-situ reduction of AuNPs to create the SERS substrate. The FL-SERS dual-mode nanoprobe exhibited excellent performance, with limits of detection (LOD) of 2.56 nM for FL mode and 1.3 pM for SERS mode. The imprinting factors were calculated to be 13.15 for FL mode and 6.06 for SERS mode, indicating the strong imprinting efficiency. Moreover, real sample applications demonstrated satisfactory recoveries ranging from 96.38 % to 101.78 %, underscoring the practical utility of the sensor in environmental monitoring. The FL-SERS dual-mode nanoprobe thus holds great potential as a versatile tool for future practical application in the sensitive detection of 4-NP in complex water environment.