Synthesis and evaluation of a metal-complexing imprinted polymer for Chinese herbs quercetin

Selective recognition and enrichment of carbamazepine in biological samples by magnetic imprinted polymer based on reversible addition-fragmentation chain transfer polymerization

A well-defined molecularly imprinted polymer (Fe₃O₄@CS@MIP) was synthesized via reversible addition-fragmentation chain transfer polymerization for magnetic solid-phase extraction coupled with high-performance liquid chromatography-diode array detector to detect carbamazepine (CBZ) in biological samples. The composition of Fe₃O₄@CS@MIP was selected by a two-step screening method. 4-vinyl pyridine, divinylbenzene and dimethylformamide were chosen as the functional monomer, cross-linker and porogen, respectively. The imprinted layer was coated on the surface of the chain transfer agent-modified magnetic chitosan nanoparticles. The prepared Fe₃O₄@CS@MIP was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller measurement and vibrating sample magnetometer. The results indicated that Fe₃O₄@CS@MIP had a large surface area (265.8 m²/g), high saturation magnetization (19.88 emu/g) and uniform structure. Besides, the binding property of the Fe₃O₄@CS@MIP was studied in detail. The Fe₃O₄@CS@MIP showed high imprinting factor (IF = 4.83) and desirable adsorption capacity (323.10 μmol/g) to CBZ. Under the optimum conditions, the developed method exhibited excellent linearity (R²>0.999) in the range of 0.01-0.5 mg/L and 1.0-30.0 mg/L, and the limits of detection were 1.0 μg/L and 9.6 μg/L for the urine and serum samples, respectively. Good recoveries (88.22%-101.18%) were obtained with relative standard deviations less than 4.83%. This work provided a practical approach for the selective extraction and detection of CBZ in real samples.

Designing a photoresponsive molecularly imprinted system on a silicon wafer substrate surface

A photoresponsive molecularly imprinted system was prepared on a silicon wafer substrate surface via the host-guest complex of grafted 4-(3-triethoxysilylpropyiureido)azobenzene (TSUA) and mono-6-deoxy-6-((p-chlorosulfonyl)-benzoic acid)-β-cyclodextrin (CBA-β-CD), and the acid-base pair interactions/hydrogen bonds between CBA-β-CD and the template molecules, including theophylline (TPE) and 4-hydroxybenzoic acid (4-HA). A molecular imprinting cycle "imprinting → extracting → uptaking → shuffling" was also defined in the study, the processes of uptaking and shuffling were investigated in detail by equilibrium binding experiments, and the Langmuir adsorption isotherm and Scatchard equation were used to evaluate the binding affinity and the theoretical binding sites of the molecularly imprinted (MIS), nonimprinted (NIS), and pure (PS) silicon wafer substrates. Compared with the NISs and PSs, the MISs showed a significantly higher adsorption capacity for the template molecules. More importantly, the MISs showed a reimprinted ability; after the process of shuffling, the molecularly imprinted systems on the substrate surface were destroyed, and new imprinted systems could be fabricated for the recognition of other template molecules after washing the substrates under irradiation at 450 nm. Moreover, the selective adsorption for the MISs was investigated, which indicated that the MISs showed specific affinity to the template molecules (TPE or 4-HA).