Imprinted Polymer Layer Research Articles

Surface‐Enhanced Raman Scattering on Molecularly Imprinted Polymers in Water

AbstractMolecularly imprinted polymer layers were prepared on SERS‐active surfaces in order to directly monitor the uptake and release of certain substances to this polymer layer by surface enhanced Raman‐scattering (SERS). The imprinting system consisted of either (2S,3S)‐(+)‐di‐O‐benzoyl‐tartaric acid (1) or N‐benzyloxycarbonyl‐(L)‐aspartic acid (2) as templates. As binding site N,N′‐diethyl‐4‐vinylbenzamidine (3) was used which binds in a 2:1 complex to the templates. The release and uptake of the templates to the imprinted polymer could be followed in aqueous solution under physiological conditions (aqueous buffer, ambient temperature). The recorded SERS bands can be unequivocally assigned to the substances taken up, and it is therefore possible to directly detect a certain substance in the imprinted layer. Release and uptake are quick processes occurring within minutes. This method also offers the opportunity to use these layers in chemosensors in which case the stability has to be further increased. SERS spectra of polymer coatings containing the template N‐benzyloxycarbonyl‐(L)‐aspartic acid (2) on gold and on silver surfaces, Raman spectra of pure 2 (template) and of a HEPES buffer solution (0.1 M, pH 7.3) which was used for the adsorption measurement.imageSERS spectra of polymer coatings containing the template N‐benzyloxycarbonyl‐(L)‐aspartic acid (2) on gold and on silver surfaces, Raman spectra of pure 2 (template) and of a HEPES buffer solution (0.1 M, pH 7.3) which was used for the adsorption measurement.

Thin layer composite molecularly imprinted membranes for selective separation of cAMP

Abstract Composite microfiltration membranes imprinted with adenosine 3′:5′-cyclic monophosphate (cAMP) were developed using photoinitiated copolymerisation of a functional monomer (diethylaminoethylmetacrylate (DEAEM), 2-hydroxyethyl methacrylate (HEMA), methacrylic acid (MA) and trimethylopropanethrimethacrylate (TRIM)) as crosslinker in the presence of cAMP as template, followed by a deposition of molecular imprinted polymer layer (MIP) on the surface of polyvinilidene fluoride (PVDF) membranes. As a result, membranes covered with a thin layer of imprinted polymer selective to cAMP were obtained with different degrees of modification. The effects of the type and concentration of the functional monomer, as well as the crosslinker's concentration, on the binding of cAMP on MIP membranes have been evaluated. It was concluded that MIP membranes binding capability is a result of both multi-sites binding to the template via hydrogen bonding and the correct position of functional groups involved in binding in imprinted polymer. Profile imaging mode atomic force microscopy has been used to visualise the surface structure of molecularly imprinted membranes and to quantify pore size and surface characteristics.

Synthesis of polymer particles with specific lysozyme recognition sites by a molecular imprinting technique

AbstractTo prepare silica beads covered with a lysozyme‐imprinted polymer layer, we polymerized acrylamide and acrylic acid or acrylamide and N,N‐dimethylaminopropylacrylamide with (NH4)2S2O8 in a phosphate buffer containing the lysozyme, surface‐modified silica beads, and crosslinkers; the result was the formation of a polymer layer with a lysozyme recognition site on the silica‐bead surface. By quantitative analysis of the supernatant of the solution containing the silica beads, we confirmed that modified silica beads, in contrast to unmodified silica beads, can selectively adsorb lysozymes. The process of binding and releasing the lysozyme to and from the modified silica beads can be repeated several times without degradation of the rebinding ability. A quartz‐crystal microbalance sensor fabricated with a molecularly imprinted polymer layer with a lysozyme recognition site was prepared. When a lysozyme aqueous solution was added to the solution in which the sensor was immersed, a high level of sensitivity and response was observed. High selectivity was also demonstrated by tests with other protein solutions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3378–3387, 2001

Molecularly Imprinted Polymers and Infrared Evanescent Wave Spectroscopy. A Chemical Sensors Approach

First steps toward a novel chemical sensor based on a molecularly imprinted polymer as the recognition element and infrared evanescent wave spectroscopy as transduction principle are presented. Noncovalently imprinted polymer layers selective for the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) have been prepared on the surface of zinc selenide attenuated total reflection elements. Selective and reversible binding of the template to the imprinted polymer could be observed on-line by Fourier transform infrared (FT-IR) spectroscopy. Control experiments were performed with nonimprinted reference polymers and with a structurally related compound. The obtained selectivity data correlate well with those previously obtained with molecularly imprinted polymers using radioligand binding assays. This demonstrates the potential for constructing stable and selective sensors for low-molecular-weight organic substances based on FT-IR spectroscopy. Moreover, FT-IR spectroscopy is demonstrated to be a valuable tool for deeper investigation of the binding mechanism in molecularly imprinted polymers.