Novel fluorescent sensor using molecularly imprinted silica microsphere-coated CdSe@CdS quantum dots and its...

In this study, a high fluorescence sensitivity and selectivity, molecularly imprinted nanofluorescent polymer sensor (MIP@SiO₂ @QDs) was prepared using a reverse microemulsion method. 2,4,6-Trichlorophenol (2,4,6-TCP) was detected using fluorescence quenching. Tetraethyl orthosilicate (TEOS), quantum dots (QDs) and 3-aminopropyltriethoxysilane (APTS) were used as cross-linker, signal sources and functional monomer respectively. The sensor (MIP@SiO₂ @QDs) and the non-imprinted polymer sensor (NIP@SiO₂ @QDs) were characterized using infra-red (IR) analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The selectivity of MIP@SiO₂ @QDs was examined by comparing 2,4,6-TCP with other similar functional substances including 2,4-dichlorophenol (2,4-DCP), 2,6-dichlorophenol (2,6-DCP) and 4-chlorophenol (4-CP). Results showed that MIP@SiO₂ @QDs had better selectivity for 2,4,6-TCP than the other compounds. Fluorescence quenching efficiency displayed a good linear response at the 2,4,6-TCP concentration range 5-1000 μmol/L. The limit of detection (LOD) was 0.9 μmol/L (3σ, n = 9). This method was equally applicable for testing actual samples with a recovery rate of 98.0-105.8%. The sensor had advantages of simple pretreatment, good sensitivity and selectivity, and wide linear range and could be applied for the rapid detection of 2,4,6-TCP in actual samples.