Preparation of Molecularly Imprinted Polymer Microspheres for Selective Solid-Phase Extraction of Capecitabine in Urine Samples

Molecularly imprinted solid-phase extraction to treat biological samples has attracted considerable attention. Herein, molecularly imprinted polymer (MIP) microspheres with porous structures were prepared by a combined suspension-iniferter polymerization method using capecitabine (CAP) as a template molecule. This material was subsequently used as a solid-phase extraction agent to separate and enrich drug molecules in urine samples. UV analysis revealed that methacrylate (MAA) was an ideal functional monomer, and 1H Nuclear Magnetic Resonance (1H NMR), Ultraviolet (UV), and Fourier transform-infrared (FT-IR) spectroscopic analyses were used to study the interaction forces between MAA and CAP, demonstrating that hydrogen bonding was the primary interaction force. MIPs with outstanding selectivity were successfully prepared, and the analysis of their surface morphology and chemical structure revealed a spherical morphology with small holes distributed across a rough surface. This surface morphology significantly reduced the mass transfer resistance of template molecules, providing an ideal template recognition effect. Using the molecularly imprinted solid-phase extraction method, CAP and the structural analog cytidine (CYT) were pretreated in urine samples and quantified by HPLC. The results showed that CAP and CYT recoveries reached 97.2% and 39.8%, respectively, with a limit of detection of 10.0–50.0 µg·mL−1. This study provides a novel approach to drug molecule pretreatment that can be applied in drug separation and functional materials science fields.

Dual-Functional Monomer MIPs and Their Comparison to Mono-Functional Monomer MIPs for SPE and as Sensors

A molecularly imprinted polymer (MIP) is a synthetic polymer that has characteristics such as natural receptors which are able to interact and bind to a specific molecule that is used as a template in the MIP polymerization process. MIPs have been widely developed because of the need for more selective, effective, and efficient methods for sample preparation, identification, isolation, and separation. The MIP compositions consist of a template, monomer, crosslinker, initiator, and porogenic solvent. Generally, MIPs are only synthesized using one type of monomer (mono-functional monomer); however, along with the development of MIPs, MIPs began to be synthesized using two types of monomers to improve the performance of MIPs. MIPs used for identification, separation, and molecular analysis have the most applications in solid-phase extraction (SPE) and as biochemical sensors. Until now, no review article has discussed the various studies carried out in recent years in relation to the synthesis of dual-functional monomer MIPs. This review is necessary, as an improvement in the performance of MIPs still needs to be explored, and a dual-functional monomer strategy is one way of overcoming the current performance limitations. In this review article, we discuss the techniques commonly used in the synthesis of dual-functional monomer MIPs, and the use of dual-functional monomer MIPs as sorbents in the MI-SPE method and as detection elements in biochemical sensors. The application of dual-functional monomer MIPs showed better selectivity and adsorption capacity in these areas when compared to mono-functional monomer MIPs. However, the combination of functional monomers must be selected properly, in order to achieve an effective synergistic effect and produce the ideal MIP characteristics. Therefore, studies regarding the synergistic effect of the MIP combination still need to be carried out to obtain MIPs with superior characteristics.

Silica-based magnetic hybrid nanocomposite for the extraction and preconcentration of some organophosphorus pesticides before gas chromatography

The precise control of pesticide residues in foodstuffs depends significantly on the clean extraction of analytes using specifically designed separation methods. In this study, a one-pot sol-gel process was used for the preparation of a magnetic hybrid silica gel tetraethylortho silicate-cyanopropyltriethoxy silane nanocomposite. The prepared material was characterized using energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, single-point specific surface area, and scanning electron microcopy. The synthesized magnetic hybrid material was used as a solid phase extraction sorbent for the extraction and preconcentration of some organophosphorus pesticides before gas chromatography with a microelectron capture detector. The performance of the proposed magnetic solid-phase extraction technique was validated by linearity (0.05-2 ng/mL), correlation coefficients (r²  = 0.9993-0.9997), limit of detection (0.02-0.06 ng/mL, S/N = 3, n = 3), and intraday (RSD = 1.5-8.7%, n = 3) and interday precision (RSD = 5.5-9.3%, n = 12), while the recovery in real samples and equilibrium adsorption capacity was 72.02-103.84% and 8-20 mg/g, respectively. The magnetic solid-phase extraction based on the hybrid nanocomposite revealed a high enrichment factor, an appropriate dynamic range, and great absorptive ability toward the selected organophosphorus pesticides spiked in real water samples.

Receptor-ligand interactions: Advanced biomedical applications

Receptor-ligand interactions (RLIs) are at the base of all biological events occurring in living cells. The understanding of interactions between complementary macromolecules in biological systems represents a high-priority research area in bionanotechnology to design the artificial systems mimicking natural processes. This review summarizes and analyzes RLIs in some cutting-edge biomedical fields, in particular, for the preparation of novel stationary phases to separate complex biological mixtures in medical diagnostics, for the design of ultrasensitive biosensors for identification of biomarkers of various diseases at early stages, as well as in the development of innovative biomaterials and approaches for regenerative medicine. All these biotechnological fields are closely related, because their success depends on a proper choice, combination and spatial disposition of the single components of ligand-receptor pairs on the surface of appropriately designed support.

Molecular imprinting: perspectives and applications

This critical review presents a survey of recent developments in technologies and strategies for the preparation of MIPs, followed by the application of MIPs in sample pretreatment, chromatographic separation and chemical sensing.