Fabrication of a near-infrared fluorescence-emitting SiO2-AuZnFeSeS quantum dots-molecularly imprinted polymer nanocomposite for the ultrasensitive fluorescence detection of levamisole
Oluwasesan Adegoke, Svetlana A. Zolotovskaya, Amin Abdolvand, Niamh Nic Daéid
Abstract
Levamisole is an anthelminthic drug that is usually used as a cutting agent to lace illicit cocaine samples and has been classified as a dangerous substance. In this work, we report on the fabrication of a novel fluorescence sensor for levamisole using AuZnFeSeS alloyed quantum dots (QDs)-molecularly imprinted polymer (MIP) nanocomposite. Firstly, organic-phased AuZnFeSeS QDs were synthesized via the organometallic hot-injection pyrolysis of metal precursors, surfactants, and organic ligands. Silica (SiO2) was then encapsulated on the QDs surface to render it compact, stable, and biocompatible. Via a free radical polymerization approach, a robust MIP shell templated with levamisole was coated around the SiO2-AuZnFeSeS QDs surface to form a AuZnFeSeS [email protected] core/shell nanocomposite. Passivation of the SiO2-AuZnFeSeS QDs core surface with the MIP shell led to radiative exciton recombination process, whereby the QDs fluorescence was enhanced. Interestingly, the SiO2-AuZnFeSeS QDs was characterized by rod-shaped and spherical-shaped particle morphology. Under optimum conditions, the fluorescence of the AuZnFeSeS [email protected] nanocomposite was quenched in the presence of levamisole and was selective against other tested drugs. Quantitative detection was achieved in the concentration range of 0.5 – 100 μM with a limit of detection of 0.05 μM (47.4 nM). Validation of the MIP-levamisole affinity was demonstrated by the superior sensitivity of the AuZnFeSeS [email protected] over the AuZnFeSeS [email protected] (non-templated material). Levamisole was successfully detected in a mixed drug sample containing cocaine with satisfactory analytical recoveries. This work is the first reported use of a cadmium-free quintenary alloyed [email protected] nanocomposite fluorescence detection system for levamisole.