Self-assembly PS@dual-emission ratiometric fluorescence probe coupled with core-shell structured MIP for the detection of malachite green in fish

Abstract

Rapid detection of malachite green (MG) by fluorescence probes of CdTe quantum dots (QDs) coated with molecularly imprinted polymer (MIP) has been reported, but low sensitivity, slow response and narrow linear range were the main disadvantages for these MIP@QDs probes. Here, an ultra-sensitive ratiometric fluorescence probe based on self-assembly functionalized polystyrene (PS) and core-shell structured MIP was developed for the detection of MG in fish. After modified with poly(diallyldimethylammonium chloride) and hexadecyl trimethyl ammonium bromide, CdTe QDs and silica encapsulated carbon quantum dots (CDs@SiO2) with negative charges, used as detection and reference fluorophores, were respectively self-assembled on the surface of PS to form PS-QDs&CDs. And a core-shell structured MIP layer was fabricated on the surface of PS-QDs&CDs to form a ratiometric fluorescence probe of MIP@PS-QDs&CDs with sol-gel method using MG, (3-aminopropyl)triethoxy-silan and tetraethyl orthosilicate as template, functional monomer and cross-linker, respectively. With intensive fluorescence densities of QDs&CDs in nucleus, the fluorescence emission of probe at λem of 630 nm could be linearly quenched by MG, while the fluorescence emission at λem of 430 nm remained unchanged. The probe of MIP@PS-QDs&CDs owned good fluorescence stability (RSD ≤2.3%), fast response time (5 min), wide linear range (0.1–32 μmol L−1) and low detection limit (5.6 μg kg−1), and has been applied to the detection of MG in fish samples with recoveries of 94.3–110.2%. The result validated that the as-prepared probe of MIP@PS-QDs&CDs had an excellent performance for MG detection in fish samples.