Molecularly imprinted polymers for enhanced impregnation and controlled release of l-tyrosine

Enantioselective Molecularly Imprinted Polymer for Tyrosine, Tryptophan, and Phenylalanine, and the Possibility of the Crop-Circle-Like Imprinting

Molecularly imprinted polymer (L-MIP) for L-tyrosine (L-Tyr) is prepared by the complexation between quaternized poly(4-vinylpyridine/divinylbenzene) (QVP) and poly(acrylamide-co-acrylic acid) (PAmA) in alkaline solution. The L-MIP shows higher enantioselectivity for L-isomers of tyrosine, together with tryptophan (Trp) and phenylalanine (Phe) compared to the D-isomers of them. The sorption isotherms of the three D-enantiomers are converged to one isotherm. It can reflect that the sorption of D-enantiomers can be relied mainly on the common segment, -CH2 -CH(NH2 )-COOH, neglecting any effect of bulkier aromatic groups. The imprinted common segment can be opened on the surface of MIP from the D-enantiomers. For the L-enantiomers, the sorption discrepancies are depended on the size of the aromatic group implying that the phenolic moiety of L-Tyr can be also opened. Thus, the imprinted sites are proposed to be opened on the surface of L-MIP similar to the crop-circle-like. The enantioselectivity factors, αef  = QL /QD , for Tyr, Trp, and Phe are 1.52, 1.30, and 1.52 for L- to D-isomers, respectively. And the uptake differences between D- and L-enantiomers of Tyr, Trp, and Phe are 31.8, 20.7, and 29 mg per 1 g MIP, respectively.

Adsorption and Recognition Property of Tyrosine Molecularly Imprinted Polymer Prepared via Electron Beam Irradiation

To realize the selective separation of L-tyrosine (L-Tyr) and avoid the drawbacks of traditional thermal polymerization, electron beam irradiation polymerization was developed for the fabrication of L-Tyr molecularly imprinted polymers (MIPs). Firstly, L-Tyr MIPs were prepared with methacrylic acid and ethylene glycol dimethacrylate and without an initiator. Then, the influence of absorbed dosage and temperature on the adsorption capacity of L-Tyr, as well as the thermodynamic behavior, were investigated. The maximum adsorption capacity of 10.96 mg/g for MIPs was obtained with an irradiation dosage of 340 kGy under 15 °C, and the ΔH0 and ΔS0 of the adsorption process are -99.79 kJ/mol and -0.31 kJ/mol·K, respectively. In addition, the effect of adsorption time on adsorption performance was evaluated under different initial concentrations, and the kinetic behavior was fitted with four different models. Finally, the recognition property of the obtained MIPs was investigated with L-Tyr and two analogues. The obtained MIPs have an imprinting factor of 5.1 and relatively high selective coefficients of 3.9 and 3.5 against L-tryptophan and L-phenylalanine, respectively. This work not only provided an L-Tyr MIP with high adsorption capacity and selectivity but also provided an effective and clean method for the synthesis of MIPs.

Rationally designed molecularly imprinted polymer membranes as antibody and enzyme mimics in analytical biotechnology

The paper is a self-review of works on development of new approaches to formation of mimics of receptor and catalytic sites of biological macromolecules in the structure of highly cross-linked polymer membranes and thin films. The general strategy for formation of the binding sites in molecularly imprinted polymer (MIP) membranes and thin films was described. A selective recognition of a number of food toxins, endocrine disruptors and metabolites is based on the results of computational modeling data for the prediction and optimization of their structure. A strategy proposed for the design of the artificial binding sites in MIP membranes was supported by the research performed by the authors on development of a number of the MIP membrane-based affinity and catalytic biosensors for selective and sensitive measurement (detection limits 0.3-100 nM) of the target analytes. Novel versatile approaches aimed at improving sensitivity of the developed biosensor systems were discussed.

Molecularly imprinted polymers: preparation, characterisation, and application in drug delivery systems

Molecular imprinting technology defines the creation of molecularly imprinted polymer (MIP) molecules in which template molecules can place in a key-lock relationship through shape, diameter, and functional groups. Although molecular imprinting technology has been employed in different fields, its applications in drug delivery systems (DDSs) have gained momentum recently. The high loading efficiency, high stability, and controlled drug release are the primary advantages of MIPs. Here, the main components, preparation methods, and characterisation tests of MIPs are summarised, and their applications in DDSs administered by different routes are evaluated in detail. The review offers a perspective on molecular imprinting technology and applications of MIPs in drug delivery by surveying the literature approximately 1998-2021 together with the outlined prospects.