Molecular Imprinting for the Preparation of Enzyme-Analogous Polymers

Wulff, Günter; Groß, Thomas; Schönfeld, Rainer; Schräder, Thomas; Kirsten, Christian

doi:10.1021/bk-1998-0703.ch002

Cited by 17 publications

(12 citation statements)

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“…For successful imprinting, high affinity between the functional monomer and the template is necessary. In addition, complex stability constants log K higher than 3 are preferred to reach stoichiometric noncovalent imprinting whereby over 95% of template is complexed in the prepolymerization mixture. ,, Stronger ion-pairing and enhanced ternary complex formation in the prepolymerization mixture might in turn have an adverse effect on designated cavity formation during the polymerization step. Moreover, since the features reported for low concentrations in Table are retained at higher concentrations under prepolymerization conditions (Table ; see also Figure ), though to a lesser extent, we set out to prepare a series of MIPs and studied in detail their rebinding behavior as a function of the chain length on the ammonium-N of the TXA cations.…”

Section: Resultsmentioning

confidence: 99%

Role of Counterions in Molecularly Imprinted Polymers for Anionic Species

et al. 2018

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Small-molecule oxoanions are often imprinted noncovalently as carboxylates into molecularly imprinted polymers (MIPs), requiring the use of an organic counterion. Popular species are either pentamethylpiperidine (PMP) as a protonatable cation or tetraalkylammonium (TXA) ions as permanent cations. The present work explores the influence of the TXA as a function of their alkyl chain length, from methyl to octyl, using UV/vis absorption, fluorescence titrations, and HPLC as well as MD simulations. Protected phenylalanines (Z-l/d-Phe) served as templates/analytes. While the influence of the counterion on the complex stability constants and anion-induced spectral changes shows a monotonous trend with increasing alkyl chain length at the prepolymerization stage, the cross-imprinting/rebinding studies showed a unique pattern that suggested the presence of adaptive cavities in the MIP matrix, related to the concept of induced fit of enzyme-substrate interaction. Larger cavities formed in the presence of larger counterions can take up pairs of Z-x-Phe and smaller TXA, eventually escaping spectroscopic detection. Correlation of the experimental data with the MD simulations revealed that counterion mobility, the relative distances between the three partners, and the hydrogen bond lifetimes are more decisive for the response features observed than actual distances between interacting atoms in a complex or the orientation of binding moieties. TBA has been found to yield the highest imprinting factor, also showing a unique dual behavior regarding the interaction with template and fluorescent monomer. Finally, interesting differences between both enantiomers have been observed in both theory and experiment, suggesting true control of enantioselectivity. The contribution concludes with suggestions for translating the findings into actual MIP development.

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Section: Resultsmentioning

confidence: 99%

Role of Counterions in Molecularly Imprinted Polymers for Anionic Species

et al. 2018

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“…However, the latter problems can be largely overcome by the design and synthesis of ªsecond generationº functional monomers which are capable of much stronger interaction with particular functional groups of the template. Examples of such ªdesignerº monomers include polymerizable amidines (2), [13] amides of nitrogen heterocycles (3) [14] and (4), [15] 5-(4-vinyl)benzyloxy-1,3-bis[2-(3,3,4,4-tetramethyl-2,5-dioxaborolanyl)-phenylcarbomoyl]benzene (5) and 2-(4vinylphenyloxy)-3,5,6-trichlorobenzoquinone (6), [16] 2,6-diamidopyridines (7), [17] designed to form strong (in some cases stoichiometric) interactions with carboxylates and phospho- Table 1. Advantages and disadvantages of the main imprinting methodologies.…”

Section: Preparation Of Imprinted Polymersmentioning

confidence: 99%

Imprinted Polymers

2001

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“…These attributes compare favorably with other strategies for producing materials capable of molecular recognition including synthetic antibodies and rationally designed small molecule receptors . Consequently, MIPs have been utilized in a wide range of applications requiring binding and selectivity including as catalysts, enzyme models, chemical sensors, and supports for enantioselective separations 1 Schematic Representation of the Imprinting Process …”

Section: Introductionmentioning

confidence: 99%

Recognition Directed Site-Selective Chemical Modification of Molecularly Imprinted Polymers

et al. 2001

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Demonstrated is the site-selective chemical modification (SSCM) of molecularly imprinted polymers (MIPs). In this strategy, MIPs are selectively chemically modified to improve the ratio of high-affinity to low-affinity binding sites and therefore the overall binding characteristics of the material. This was accomplished by preferentially eliminating the low-affinity binding sites by esterification with diazomethane or phenyldiazomethane. Selectivity in the esterification reaction was achieved using a guest molecule as an in situ protecting group that preferentially shields the high-affinity sites and leaves the low-affinity sites exposed toward reaction. The corresponding shifts in the populations of high- and low-affinity sites were quantified using affinity distribution analysis, which quantitatively measures the heterogeneous distribution of binding sites in MIPs as number of binding sites (N) with respect to binding affinity (K). Using affinity distribution analysis, the SSCM strategy was shown to improve the percentage of high-affinity sites in a methacrylic acid (MAA)/ethylene glycol dimethacrylate (EGDMA) matrix, imprinted with ethyl adenine-9-acetate (EA9A) in acetonitrile. The effects of different solvents and concentrations of guest molecule on the SSCM also were examined. The greatest improvements due to SSCM were observed when carried out in the imprinting solvent (acetonitrile). The demonstrated SSCM methodology is complementary to existing strategies for improving MIPs and thus can be utilized in tandem to improve the binding characteristics of MIPs.

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Molecular Imprinting for the Preparation of Enzyme-Analogous Polymers

Cited by 17 publications

References 0 publications

Role of Counterions in Molecularly Imprinted Polymers for Anionic Species

Role of Counterions in Molecularly Imprinted Polymers for Anionic Species

Imprinted Polymers

Recognition Directed Site-Selective Chemical Modification of Molecularly Imprinted Polymers

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