Synthetic Creatinine Receptor: Imprinting of a Lewis Acidic Zinc(II)cyclen Binding Site to Shape Its Molecular Recognition Selectivity

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• 作者：Michael Subat ; Andrew S. Borovik ; and Burkhard Kö ; nig
• 刊名：Journal of the American Chemical Society
• 出版年：2004
• 出版时间：March 17, 2004
• 年：2004
• 卷：126
• 期：10
• 页码：3185 - 3190
• 全文大小：97K
• 年卷期：v.126,no.10(March 17, 2004)
• ISSN：1520-5126

文摘

Molecularly imprinted polymers (MIPs) from polymerizable Lewis acidic zinc(II)cyclen complexesand ethylene glycol dimethyl acrylate have been prepared. For the imprinting process the template moleculecreatinine is reversibly coordinated to the zinc atom. The high strength of this interaction allows analytebinding to the MIP from aqueous solution with high affinity. Its pH dependence is used for controlled guestrelease with nearly quantitative analyte recovery rate. The binding capacity and selectivity profile of theMIP remains constant through several pH controlled binding and release cycles. MIPs missing a suitablemetal binding site showed no significant affinity for thymine or creatinine. Flavin adsorbs nonspecifically toall polymers. The imprinting process reverses the binding selectivity of zinc(II)cyclen for creatinine andthymine from 1:34 in homogeneous solution to 3.5:1 in the MIP. Scatchard plot analysis of creatinine bindingisotherms reveals uniform binding of the imprint, with fits indicating a one-site model; however, similaranalysis for thymine indicate high and low affinity sites. This corresponds to unrestricted coordination sitesfreely accessible for thymine, e.g., at the polymer surface, and misshaped imprinted sites, which still canaccommodate thymine. More than 50% of all binding sites exclusively bind creatinine and are not accessibleto thymine. The binding properties of a copolymer of polymerizable zinc(II)cyclen and ethylene glycol dimethylacrylate missing the creatinine template, which match the binding selectivity of the complex in solution,confirm that the origin of altered selectivities is the imprinting process. With binding ability at physiologicalpH, the MIPs are applicable for tasks in medicinal diagnostics or biotechnology. Imprinted zinc(II)cyclencomplexes provide, like a metalloenzyme binding motif, high binding affinity by reversible coordinationwhile the surrounding macromolecule determines binding selectivity.