Stereoselective release behaviors of imprinted bead matrices

Molecular imprinted polymers as drug delivery vehicles

This review is aimed to discuss the molecular imprinted polymer (MIP)-based drug delivery systems (DDS). Molecular imprinted polymers have proved to possess the potential and also as a suitable material in several areas over a long period of time. However, only recently it has been employed for pharmaceuticals and biomedical applications, particularly as drug delivery vehicles due to properties including selective recognition generated from imprinting the desired analyte, favorable in harsh experimental conditions, and feedback-controlled recognitive drug release. Hence, this review will discuss their synthesis, the reason they are selected as drug delivery vehicles and for their applications in several drug administration routes (i.e. transdermal, ocular and gastrointestinal or stimuli-reactive routes).

Application of molecularly imprinted hydrogel for the preparation of lactose-free milk

BACKGROUND

A variety of lactose imprinted hydrogels were prepared and their binding properties were studied in comparison with blank non-imprinted hydrogel. Methacrylamide and ethylene glycol dimethacrylate were used as functional monomer and cross-linker, respectively. Dimethylsulfoxide was also applied as polymerisation solvent.

RESULTS

Different template/monomer ratios were studied and the optimised imprinted hydrogel (MIP₂), with a lactose/methacrylamide ratio of 1:8, was selected in a rebinding test. In Scatchard analysis of MIP₂-lactose interactions, the dissociation constant and maximum binding sites were 0.33 mmol L⁻¹ and 67.76 µmol g⁻¹ hydrogel, respectively. The selectivity of MIP₂ for lactose in aqueous media was also evaluated in comparison with different mono- and disaccharides. The data showed that the affinity of MIP₂ for lactose is significantly higher than other saccharides. The imprinted hydrogel was finally used as a sorbent for separation of lactose from milk.

CONCLUSIONS

The results indicated that MIP₂, as an optimised imprinted hydrogel, can effectively bind lactose and decrease its concentration in milk.

Mimicking Biological Delivery Through Feedback-Controlled Drug Release Systems Based on Molecular Imprinting

Intelligent drug delivery systems (DDS) are able to rapidly detect a biological event and respond appropriately by releasing a therapeutic agent; thus, they are advantageous over their conventional counterparts. Molecular imprinting is a promising area that generates a polymeric network which can selectively recognize a desired analyte. This field has been studied for a variety of applications over a long period of time, but only recently has it been investigated for biomedical and pharmaceutical applications. Recent work in the area of molecularly imprinted polymers in drug delivery highlights the potential of these recognitive networks as environmentally responsive DDS that can ultimately lead to feedback controlled recognitive release systems.

Recognitive biomimetic networks with moiety imprinting for intelligent drug delivery

Molecular imprinting techniques have been developed for the preparation of biomimetic polymer networks that can recognize a general moiety, D-glucose, and the novel evaluation of loading and release of a larger molecule with glucose as an integral part of its structure [i.e., fluorescently tagged glucose (2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxy-glucose) or 2-NBDG]. Poly(acrylamide-co-poly(ethylene glycol)dimethacrylate) networks with varying crosslinking monomer percentages (80, 67, and 30%) and crosslinker lengths (average number of ethylene glycol units of 1, 4, and 14) were prepared and characterized using a novel fluorescent microscopy technique, which allowed for microscale observation of the dynamic binding and release of 2-NBDG within the polymer film. Experimental results indicate that tighter mesh-sized networks had increased affinity and capacity towards the glucose functionalized molecule as well as increased diffusional transport times, indicating the strong potential to load significantly higher amounts of therapeutic within intelligent carriers as well as control and extend the rate of release via macromolecular structure.

Chiral recognition applications of molecularly imprinted polymers: a critical review

Molecular imprinting technology offers the unique opportunity to tailor chiral stationary phases with predefined chiral recognition properties by employing the enantiomers of interest as binding-site-forming templates. Added advantages, such as ease of preparation, chemical robustness, low-cost production, and the possibility of shaping molecularly imprinted polymers (MIPs) in various self-supporting formats, render them attractive materials for a broad range of chiral recognition applications. In this review a critical overview on recent developments in the field of MIP-based chiral recognition applications is given, focusing on separation techniques and molecular sensing. Inherent limitations associated with the use of enantioselective MIP materials in high-performance separation techniques are outlined, including binding site heterogeneity and slow mass transfer characteristics. The prospects of MIP materials as versatile recognition elements for the design of enantioselective sensor systems are highlighted.

Composite membrane of bacterially-derived cellulose and molecularly imprinted polymer for use as a transdermal enantioselective controlled-release system of racemic propranolol

A composite membrane for transdermal delivery of S-propranolol enantiomer was developed based on the controlled pore functionalization of bacterial cellulose membranes using a molecularly imprinted polymer (MIP) layer synthesis. The reactive pore-filling of an asymmetric porous cellulose membrane with a MIP thin-layer was effected using a silanized coupler as an additional anchor for the MIP. MIP thin-layers with specific binding sites for S-propranolol were synthesized by copolymerization of methacrylic acid with a cross-linker, ethylene glycol dimethacrylate in the presence of S-propranolol as the template molecule and the latter was subsequently extracted. Selective transport of S-propranolol through the MIP composite membrane was obtained, although this was determined mostly by the parent cellulose membrane with some ancillary contributory effect from the MIP layer. In addition, an enantioselectivity in the transport of propranolol prodrug enantiomers was found, suggesting that the shape and functional groups orientation, which are similar to that of the print molecule were essential for enantiomeric recognition of the MIP composite membrane. The enantioselectivity of S-MIP membranes was also shown when the release of propranolol enantiomers was studied in vitro using rat skin, with racemic propranolol contained in the donor compartment. The composite membrane of bacterially-derived cellulose and molecularly imprinted polymer may have great potential for use as a transdermal enantioselective controlled-release system for racemic propranolol.

Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003

Over 1450 references to original papers, reviews and monographs have herein been collected to document the development of molecular imprinting science and technology from the serendipitous discovery of Polyakov in 1931 to recent attempts to implement and understand the principles underlying the technique and its use in a range of application areas. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by papers dealing with fundamental aspects of molecular imprinting and the development of novel polymer formats. Thereafter, literature describing attempts to apply these polymeric materials to a range of application areas is presented.

Molecularly imprinted materials as advanced excipients for drug delivery systems

The application of the molecular imprinting technology in the design of new drug delivery systems (DDS) and devices useful in closely related fields, such as diagnostic sensors or biological traps, is receiving increasing attention. Molecular imprinting technology can provide polymeric materials with the ability to recognize specific bioactive molecules and with a sorption/release behaviour that can be made sensitive to the properties of the surrounding medium. In this review, an introduction to the imprinting technology presenting the different approaches in preparing selective polymers of different formats is given, and the key factors involved in obtaining of imprinted binding sites in materials useful for pharmaceutical applications are analysed. Examples of DDS based on molecularly imprinted polymers (MIPs) can be found for the three main approaches developed to control the moment at which delivery should begin and/or the drug release rate; i.e., rate-programmed, activation-modulated or feedback-regulated drug delivery. This review seeks to highlight the most remarkable advantages of the imprinting technique in the development of new efficient DDS as well as to point out some possibilities of adapting the synthesis procedures to create systems compatible with both the relative instable drug molecules, especially of peptide nature, and the sensitive physiological tissues with which MIP-based DDS would enter into contact when administered. The prospects for future development are also analysed.

Molecularly imprinted polymers for drug delivery

Molecular imprinting technology has an enormous potential for creating satisfactory drug dosage forms. Although its application in this field is just at an incipient stage, the use of MIPs in the design of new drug delivery systems (DDS) and devices useful in closely related fields, such as diagnostic sensors, is receiving increasing attention. Examples of MIP-based DDS can be found for the three main approaches developed to control the moment at which delivery should begin and/or the drug release rate, i.e. rate-programmed, activation-modulated, or feedback-regulated drug delivery. The utility of these systems for administering drugs by different routes (e.g. oral, ocular or transdermal) or trapping undesired substances under in vivo conditions is discussed. This review seeks to highlight the more remarkable advantages of the imprinting technique in the development of new efficient DDS as well as pointing out some possibilities to adapt the synthesis procedures to create systems compatible with both the relative instable drug molecules, especially of peptide nature, and the sensitive physiological tissues with which MIP-based DDS would enter into contact when administered. The prospects for future development are also analysed.

Configurational biomimesis in drug delivery: molecular imprinting of biologically significant molecules

This review focuses on trends in the macromolecular recognition of biologically significant molecules (e.g., drugs, amino acids, steroids, nucleotide bases, carbohydrates, etc.) via molecular imprinting methods. An extensive list of prior art including type of functional monomers and crosslinkers for each biomolecule imprinted polymer is presented. Representative samples of receptor-ligand dissociation constants and polymer capacities are presented as well as typical values that occur in classes of biological recognition systems. Imprinting technology has direct impact in enhanced drug loading of controlled-release carriers for the sustained release of therapeutic agents as well as robust biosensors for novel therapeutic and diagnostic devices. This review also discusses the future of designed recognition, configurational biomimesis within polymeric gels, and highlights recent efforts toward integrating imprinted polymers in controlled drug delivery systems and sensing devices. In particular, the application of imprinted polymers for sustained release, enhanced loading capacity, and enantioselective loading or release are discussed. This article also highlights the most important problems to be solved in the design of synthetic recognition-based networks for biological molecules.