Composite QDs@MIP Nanospheres for Specific Recognition and Direct Fluorescent Quantification of Pesticides in Aqueous Media

Abstract

Quantum dots (QDs)-based molecularly imprinted polymer (MIP) composite nanospheres were successfully prepared via a facile and versatile ultrasonication-assisted encapsulation method. Unlike the hydrogen-bond-based MIPs, these so-prepared QDs-MIP composite nanospheres, relying on the interaction including van der Waals forces and hydrophobic forces, demonstrated excellent selectivity in aqueous media. Their small particle sizes and carboxyl-enriched polymer matrixes give rise to their good dispersibility and stability in aqueous solution, and faster adsorption and desorption kinetics, which further make them extensively applicable for chemical/biological sensors in aqueous media. Based on the fluorescence quenching via template analytes (diazinon) rebinding into the recognition cavities in the polymer matrixes, the QDs-MIP nanospheres were successfully applied to the direct fluorescence quantification of diazinon, independent of extracting templates from the MIP nanospheres, as well as further complicated and time-consuming assays. This novel method can selectively and sensitively detect down to 50 ng/mL of diazinon in water, and a linear relationship has been obtained covering the concentration range of 50-600 ng/mL. The present studies provide a new and general strategy to fabricate other multifunctional (luminescent and magnetic) inorganic-organic MIP nanocomposites with highly selective recognition ability in aqueous media and are pretty desirable for biomedical/chemical sensing applications.

Quantum Dots Based Mesoporous Structured Imprinting Microspheres for the Sensitive Fluorescent Detection of Phycocyanin

“…More efforts still need to be made to further enhance the sensitivity of MIPs based QDs systems while retaining their high selectivity. On the other hand, the developed MIP-coated CdSe QDs for ractopamine 21 and ZnS/Mn QDs@MIP for diazinon 24 attain relatively high sensitivity, but their response time is relatively long ( Table 2). Possibly, reducing the MIP-shell thickness and providing (meso)porous structures are two effective ways to improve sensitivity and shorten response time.…”

“…MIPs based composite materials combine the favorable molecular recognition specificity of MIPs with additional functions of other materials such as mesoporous silica, which are more suitable in practical applications. 24 Mesoporous silica materials possess large pore volume and nanosized pore wall thickness and therefore have become popular substrates in surface imprinting. 27 The recognition sites of imprinted mesoporous silica materials are located near to the surface, which offers high accessibility for target molecules; this is especially important for a highly cross-linked matrix because it hinders molecules from moving freely.…”

Development and Applications of Quantum Dot-based Molecularly Imprinted Polymer Composites for Optosensing of Carbofuran in Water

“…Carbofuran MIPs were synthesized by a multi-step swelling and polymerization method, [28][29][30] and then further labeled with CdSe/ZnS QDs via gradual solvent evaporation method. 31 The synthesis method of carbofuran MIPs was as follows.…”

“…Nowadays there are various mechanism explanations, such as fluorescence resonance energy transfer, charge transfer and quantum dot surface lattice defects. 30,35,36 In this work, ultraviolet spectrophotometer was employed to explore the mechanism of the fluorescence quenching. The UV-vis spectra of carbofuran and QDs-MIP are shown in Fig.…”

Quantum Dots Extraction Coupled With High-Performance Liquid Chromatography for the Determination of Polycyclic Aromatic Hydrocarbons in Water

“…The applications of QDs have been reported in a medical field as the bio-markers (Bruchez et al, 1998;Chan and Nie, 1998) Zhao et al, 2012). To the best of our knowledge, there is no report on the use of QDs for pre-concentration purposes.…”