Design and evaluation of thin and flexible theophylline imprinted polymer membrane materials.
ABSTRACT The aim of this work was to produce a thin, flexible and diffusion able molecularly imprinted polymeric matrix with good template accessibility. Membranes were prepared using a non-covalent molecular imprinting approach and their physical characteristics and binding capabilities investigated. Two materials were used, a poly(tri-ethyleneglycol dimethyacrylate-co-methyl methacrylate-co-methacrylic acid) copolymer containing 14% cross-linker and a monomer (g) to porogen (ml) ratio of 1:0.5 (A), and a blend of poly(TEGMA-co-MAA) and polyurethane (B). The polyurethane was added to improve membrane flexiblity and stability. The polymers were characterized using AFM, SEM and nitrogen adsorption, whilst binding was evaluated using batch-rebinding studies. For all membranes the specific surface area was low (<10 m(2)/g). MIP (A) films were shown to bind specifically at low concentrations but specific binding was masked by non-specific interactions at elevated concentrations. Selectivity studies confirmed specificity at low concentrations. K(D) approximations confirmed a difference in the population of binding sites within NIP and MIP films. The data also indicated that at low concentrations the ligand-occupied binding site population approached homogeneity. Scanning electron microscopy images of membrane (B) revealed a complex multi-layered system, however these membranes did not demonstrate specificity for the template. The results described here demonstrate how the fundamental parameters of a non-covalent molecularly imprinted system can be successfully modified in order to generate flexible and physically tolerant molecularly imprinted thin films.
Article: To Remove or Not to Remove? The Challenge of Extracting the Template to Make the Cavities Available in Molecularly Imprinted Polymers (MIPs).[show abstract] [hide abstract]
ABSTRACT: Template removal is a critical step in the preparation of most molecularly imprinted polymers (MIPs). The polymer network itself and the affinity of the imprinted cavities for the template make its removal hard. If there are remaining template molecules in the MIPs, less cavities will be available for rebinding, which decreases efficiency. Furthermore, if template bleeding occurs during analytical applications, errors will arise. Despite the relevance to the MIPs performance, template removal has received scarce attention and is currently the least cost-effective step of the MIP development. Attempts to reach complete template removal may involve the use of too drastic conditions in conventional extraction techniques, resulting in the damage or the collapse of the imprinted cavities. Advances in the extraction techniques in the last decade may provide optimized tools. The aim of this review is to analyze the available data on the efficiency of diverse extraction techniques for template removal, paying attention not only to the removal yield but also to MIPs performance. Such an analysis is expected to be useful for opening a way to rational approaches for template removal (minimizing the costs of solvents and time) instead of the current trial-and-error methods.International Journal of Molecular Sciences 01/2011; 12(7):4327-47. · 2.60 Impact Factor