Synthesis of molecularly imprinted carbon dot grafted YVO4:Eu3+ for the ratiometric fluorescent determination of paranitrophenol

A facilely prepared ratiometric fluorescent molecularly imprinted sensor has been constructed for highly sensitive and selective detection of 4-nitrophenol (4-NP) using carbon dots (CDs) as the target sensitive fluorophore and YVO4: Eu3+ nanoparticles (NPs) as the reference fluorophore. Through the hydrolysis and condensation reactions of the silica precursor, CDs and YVO4 Eu3+ NPs can be incorporated into silica networks through silylation reaction by one pot synthesis procedure. The as-prepared fluorescent molecularly imprinted sensor shows characteristic fluorescence emissions of CDs (blue) and YVO4:Eu3+ (red) under a single excitation wavelength. With the addition of 4-NP, the fluorescence of CDs is selectively quenched, resulting in the ratiometric fluorescence response. Under optimum conditions, the proposed sensor exhibits a high sensitivity with a linear range from 0 to 12.0 μM and shows the limit of detection as low as 0.15 μM in the determination of 4-NP, which is probably benefits from the tailor-made imprinted cavities for binding 4-NP. Furthermore, the proposed method was successfully applied for the determination of 4-NP in real water samples and human urine samples with great potentials for monitoring of 4-NP in environmental application.