A technique allowing high-throughput synthesis and evaluation of molecularly imprinted polymer sorbents at a reduced scale (mini-MIPs) was developed and used for the optimization of MIPs for use in pure aqueous environments. The technique incorporated a 4-port liquid-handling robot for the rapid dispensing of monomers, templates, solvents and initiator into the reaction vessels of a 96-well plate. A library of 80 polymers, each ca. 50 mg, could thus be prepared in 24 h. The MIP rebinding capacity and selectivity could be rapidly assessed in the batch mode by quantifying nonbound fractions in parallel using a UV monochromator plate reader. This allowed a complete evaluation of the binding characteristics of an 80 polymer library in approximately 1 week. With the objective of optimizing a polymer imprinted with the local anaesthetic Bupivacaine for use in pure aqueous systems, a polymer library was prepared by varying the original poly(MAA-co-EDMA) MIP composition. The variable factors were the added amount of the hydrophilic comonomer, 2-hydroxyethyl methacrylate (HEMA), the cross-linking ratio, and the porogen. This optimization resulted in polymers showing high imprinting factors (IF = K(MIP)/K(NIP)) in water as a result, mainly, of reduced binding to the nonimprinted polymer. Normal scale batches of these materials showed strong retention of the template and low nonspecific binding when assessed as chromatographic stationary phases using pure phosphate buffer, pH 7.4, as mobile phase, by equilibrium batch rebinding experiments and as sorbents for extractions of the analyte from blood plasma samples.

SummaryMolecularly imprinted polymers have been evaluated at the sample clean-up stage in the analysis of a drug lead compound. In order to circumvent quantification problems related to bleeding of the template, a structurally related analogue of the latter was used. This was selected based on criteria related to interaction site location, solubility, availability and stability of the analogue. Selection of suitable polymerisation conditions was then made using a small batch format (ca. 50 mg) and rapid assessment of binding in the equilibrium mode. It was found that the amount of template could be greatly reduced compared to the conventional protocol, requiring only 5 I~mol of template per gram of polymerwithout seriously compromising the performance of the materials for chromatographic orSPE applications.

A high throughput synthesis technique was developed for the combinatorial optimization of polymers imprinted with 17□-Estradiol. This incorporated a liquid handling robot for the rapid dispensing of monomers, templates, solvents and initiator into the reaction vessels of a 96-well plate. A library of 80 polymers, each ca 80mg, was prepared using functional monomers containing acid functionalities (methacrylic acid (MAA), trifluoromethylacrylic acid (TFMAA)), basic functionalities (2-vinylpyridine (2-Vpy), 4-vinylpyridine (4-Vpy), diethyl-2-aminoethylmethycrylate (DEAEMA)) or neutral functional groups (2-hydroxyethylmethacrylate (HEMA), methacrylamide (MAAM), N-vinylpyrrolidone (NVP), acetoxystyrene (AST)). Four replicas each of imprinted and nonimprinted polymers were made for each functional monomer using ethyleneglycoldimethacrylate (EDMA) as crosslinking monomer and acetonitrile as solvent. Polymer washing and exchange of incubation solutions could be effectively carried out after transfer of the polymers to solvent resistant filter plates. The binding properties of the polymers could then be rapidly assessed in the batch mode by quantifying non-bound fractions in parallel using a fluorescence monochromator plate reader. These data showed an acceptable agreement with the data from a corresponding HPLC evaluation of the rebinding solutions. In agreement with other reports, the acid functional monomers MAA and TFMAA, the basic DEAEMA and the neutral MAAM exhibited the highest imprinting factors.