Core-shell quantum dots coated with molecularly imprinted polymer for selective photoluminescence sensing of perfluorooctanoic acid.

A photoluminescence (PL) sensor based on core-shell quantum dots (QDs) coated with molecularly-imprinted polymer (MIP) shell was designed for the determination of perfluorooctanoic acid (PFOA) in water. PFOA is a persistent and bioaccumulating water contaminant whose detection is of great importance for ensuring safe water supplies. We demonstrate a simple method to fabricate CdTe@CdS QDs and then encapsulate them with a molecularly-imprinted silica film in a one-pot sol-gel reaction. The final composite was created by anchoring the MIP layer on the CdTe@CdS QDs using 3-aminopropyltriethoxysilane (APTES) as functional monomer and tetraethoxysilane (TEOS) as crosslinker in the presence of aqueous ammonia. The combination of QDs and MIP showed stable photoluminescence and good selectivity. The PL of the MIP-coated QDs composite was efficiently quenched when PFOA molecules occupied the templated binding sites. The composite was applied to the detection of PFOA and exhibited a good linearity in range of 0.25-15.00 µmol/L with a detection limit of 25 nmol/L (~10 ppb by mass). The proposed method has been applied successfully for the determination of trace PFOA in environmental water samples and has demonstrated its robustness in the presence of other molecules and ions.