Fluorescent sensing of homocysteine by molecular imprinting

The feasibility of biomimetic molecular sensing of homocysteine, an independent risk factor for cardiovascular diseases, was studied. The sensing approach coupled fluorescent derivatization of dl-homocysteine by a thiol-specific fluoro-tagging agent, N-(1-pyrenyl)maleimide, with molecular recognition by a molecularly imprinted polymer (MIP) matrix. The non-covalent MIP was fabricated using the N-(1-pyrenyl)maleimide-dl-homocysteine (PM-H) adduct as template. The PM-H-MIP was found to possess outstanding analyte-specific affinity for PM-H with binding constant, K_B, of 9.28±1.6×10⁵ M⁻¹ and density of recognition sites, B_max, of 11.9±0.8 nmol/g dried MIP. Following in situ fluorescent derivatization, luminescent response of the MIP was found to correlate linearly with concentration of dl-homocysteine in the range corresponding to realistic total homocysteine concentration in blood plasma. Besides being a passive recognition matrix for the binding of the fluoro-tagged analyte, the PM-H-MIP material was found to be able to specifically enhance the rate of derivatization reaction between dl-homocysteine and N-(1-pyrenyl)maleimide. In a sense, the MIP transformed a fluoro-tagging agent, which is generally reactive towards a broad spectrum of thiol-containing species, into a dl-homocysteine-specific derivatizing agent. The mechanism of such analyte-specific enhancement of derivatization rate and its advantages to the biomimetic molecular sensing are discussed.     

基于分子印迹技术的牛血清白蛋白电位式传感器的研究

以牛血清白蛋白(BSA)为模板,合成了分子印迹聚合物凝胶(MIP),进而制得了以聚氯乙烯(PVC)为支撑膜的BSA电位式传感器。采用直接电位法测得BSA在浓度0.1～1.0 mg/mL范围内与电位呈线性关系。此电极制作简单,可用于BSA的测定。     

分子印迹技术研究进展

分子印迹是制备具有分子特异识别功能聚合物的一种技术。本文从分子印迹聚合物的识别机理、分子印迹聚合制备条件和制备技术三个方面综述了分子印迹的研究进展,最后展望了分子印迹发展前景。引用文献66篇。     

Bisphenol A-recognition polymers prepared by covalent molecular imprinting

A specific recognition material for bisphenol A (BPA) was prepared by using a covalent imprinting technique. A chloroform solution containing bisphenol A dimethacrylate as a template, ethylene glycol dimethacrylate as a cross-linking agent and 2,2′-azobis(isobutyronitrile) as an initiator was polymerized by UV initiation. When BPA was removed from the resulting polymer by hydrolysis of the ester bonds with aqueous sodium hydroxide, carboxylic acid residues were generated in the polymer. After the polymer was packed into a stainless steel column, retention factors of BPA and related compounds were measured. The imprinted polymer adsorbed BPA and structurally related compounds such as 4,4′-dihydroxybenzophenone, bis(4-hydroxyphenyl)sulfone and 4,4′-dihydroxybiphenyl. A typical association constant (K_a) was calculated to be 1.72×10⁵ M⁻¹ by Scatchard analysis. Interestingly, 17α- and 17β-estradiol were also bound to the imprinted polymer (K_a=1.68×10⁵ M⁻¹), indicating that the polymer could be used as artificial receptors for screening the compounds having estrogenic action.     

Photochemical molecular imprinting of cholesterol

Cinnamoylated photocrosslinkable cyclodextrin derivatives (BCC) were synthesized by the substitution of β-cyclodextrin (β-CD) with cinnamoyl chloride (CC) and crosslinked with either hexamethylenediisocyanate (HMDI) or toluenediisocyanate (TDI). Cyclodextrin rings were substituted with one or two cinnamoyl moieties, as found from mass spectrometry. The polymeric matrix with cholesterol molecular imprint was obtained on irradiation of molecular assembly formed by the cinnamoyl-functionalized β-cyclodextrin-cholesterol with light at 275 nm, absorbed exclusively by the cinnamoyl chromophores. Irradiation induced crosslinking due to the photodimerization of the cinnamoyl moieties. To determine the adsorption properties of the produced material imprinting was performed in the presence of tritiated cholesterol and the intensity of β radiation from the material was measured. The materials obtained by the adsorption of tritiated cholesterol by nonirradiated polymer were used as controls. It was found that the polymer photocrosslinked in the presence of cholesterol have shown a considerable higher adsorption capacity for cholesterol than the control materials. This confirmed successful formation of molecularly imprinted polymer (MIP) by photochemical crosslinking. The selectivity of imprinting was also confirmed using compounds of similar structures, i.e. ergosterol, dehydroergosterol, and Vitamin D.     

分子印迹技术在黄曲霉毒素检测中的最新研究进展EI北大核心CSCD

黄曲霉毒素(AFT)是由黄曲霉和寄生曲霉等某些菌株产生的一类真菌毒素,主要包括B1,B2,G1,G2,M1,M2,GM,P1,Q1,毒醇等,其中B1的毒性最大,致癌性最强,其广泛存在土壤、动植物、各种坚果、谷物,奶,食用油及其制品中,因此,食品中超痕量及痕量的黄曲霉毒素的检测方法受到高度关注。由于农产品样品基质复杂,而黄曲霉毒素含量和限量极低,高效特异性样品前处理技术是高灵敏精准检测黄曲霉毒素的关键之重。近年来分子印迹技术在样品前处理和核心识别元件等方面发展迅猛,在黄曲霉毒素痕量检测方面凸显出一定优势。综述了近几年来分子印迹技术在黄曲霉毒素前处理及快速检测等方面最新研究进展,并展望了分子印迹技术在黄曲霉检测应用的发展前景。     

Synthesis of polyacrylamide gel beads with electrostatic functional groups for the molecular imprinting of bovine serum albumin

Synthetic materials capable of recognizing proteins are important in separation, biosensors and biomaterials. In this study, bovine serum albumin-imprinted soft-wet polyacrylamide gel beads were prepared via inverse-phase suspension polymerization, using acrylamide and N,N′-methylene diacrylamide as polymeric matrix components and methacrylic acid as functional monomer. The adsorption study showed, through the imprinting process, that the imprinted gel beads had much higher adsorption capacity than the nonimprinted gel beads, and that the matching of the surface zeta-potential between the templates and the imprinted gel beads can enhance the imprinting effect. Adsorption kinetics indicated that the adsorption process could be described as an apparent first-order kinetic process for the gel beads. From the adsorption isotherm curve, we found that the adsorption of the imprinted gel beads was in agreement with the Langmuir adsorption model. Moreover, selectivity testing of the imprinted gel beads showed that imprinted gel beads exhibited good recognition for BSA as compared to the control protein. We speculate that the formation of complementary shapes and multiple-point electrostatic interactions between the imprinting cavities and the template proteins are the two factors that lead to the imprinting effect.      

Nanotemplating for two-dimensional molecular imprinting

A new 2D molecular imprinting technique based on nanotemplating and soft-lithography techniques is reported. This technique allows the creation of target-specific synthetic recognition sites on different substrates using a uniquely oriented and immobilized template and the attachment of a molecularly imprinted polymer on a substrate. The molecularly imprinted polymer was characterized by AFM, fluorescence microscopy, and ATR-FTIR. We evaluated the rebinding ability of the sites with theophylline (the target molecule). The selectivity of the molecularly imprinted polymer was determined for the theophylline-caffeine couple. The molecularly imprinted polymer exhibited selectivity for theophylline, as revealed by competitive rebinding experiments. Fluorescence microscopy experiments provided complementary proof of the selectivity of the molecularly imprinted polymer surfaces toward theophylline. These selective molecularly imprinted polymers have the potential for chemical sensor applications. Because of its 2D nature, this novel chemical sensor technology can be integrated with many existing high-sensitivity multichannel detection technologies.     

Atrazine transformation using synthetic enzymes prepared by molecular imprinting

Atrazine imprinted synthetic polymers were prepared using a combination of methacrylic acid and 2-sulfoethyl methacrylate that bound and converted atrazine and other 6-chlorotriazine herbicides to less toxic compounds. A chloride at the 6-position of the triazines was converted to a methoxy group by the polymer in a methanol-containing solvent, where the imprinting effects enhanced the catalytic activity. Competitive inhibition of the atrazine methanolysis was observed in the presence of a structurally related binder, ametryn, suggesting that the catalytic reaction proceeded in the binding sites generated by the molecular imprinting process.     

Molecular sensing of 3-chloro-1,2-propanediol by molecular imprinting

A covalent interaction-based molecularly imprinted polymer (MIP) material for 3-chloro-1,2-propanediol (3-MCPD), a post-testicular anti-fertility agent and possible carcinogen and mutagen in food products containing acid-hydrolyzed vegetable proteins, has been successfully fabricated using 4-vinylphenylboronic acid as the functional monomer. Rebinding assay revealed that the binding constant, K_B, for the receptor sites and non-specific sites are 1.93±0.1×10⁴ and 2.74±0.7×10² M⁻¹, respectively. The estimated number of receptor site, B_max, imprinted is 123.3±3 μmol/g of MIP. The MIP material is able to act as a potentiometric chemosensor for 3-MCPD via increase in Lewis acidity of the receptor sites upon reaction of the arylboronic acid with 3-MCPD to form the more acidic arylboronic acid esters. A simple pH glass electrode is sufficient to monitor the analyte-specific rebinding. In unbuffered aqueous media, linear potentiometric response from 0 to 350 ppm of 3-MCPD can be achieved. The MIP-based chemosensing in a soya sauce matrix has also been attempted. It is found that the dynamic range of the potentiometric chemosensing response of the MIP material is much reduced, probably due to the blocking or deactivation of receptor sites by interferents in soya sauces. Nevertheless, the present work demonstrated the feasibility of using MIP-based chemosensors as semi-quantitative analytical tools for screening purposes in quality control of food products.     

分子印迹技术研究进展

分子印迹技术是制备对特定目标分子具有特异性识别能力的高分子材料的技术,所制备的高分子材料被称为分子印迹聚合物.分子印迹聚合物因具有预定性、识别性和实用性三大优点已广泛应用于分离、模拟抗体与受体、催化剂以及仿生传感器等方面和领域,显示出了广泛的应用前景.作者对分子印迹技术的发展历史、基本原理、分类、应用现状以及一些新的研究热点进行了综述.     

Atrazine transforming polymer prepared by molecular imprinting with post-imprinting process

Molecularly imprinted polymers bearing atrazine transforming activity were prepared by using newly designed templates that are atrazine analogues attached with an allyl or a styryl group via a disulfide bond at the 6-position, methacrylic acid as a functional monomer and styrene/divinylbenzene as crosslinkers. After polymerization, the disulfide bond was reduced to remove the atrazine moiety from the polymer matrix, followed by oxidation of the remaining thiol group to generate sulfonic acid (post-imprinting treatment), so that both a methacrylic acid residue and a sulfonic acid residue existed in an atrazine-imprinted cavity. The polymers indicated the selective binding of triazine herbicides and catalytic activity for methanolysis at the 6-position of atrazine, yielding a low toxic atraton.     

Crown-ether functionalised second coordination sphere palladium catalysts by molecular imprinting

Functionalisation of the second coordination sphere of a molecularly imprinted Pd complex was achieved by localising within the polymeric cavity a crown-ether receptor capable of altering the catalytic activity of the reactive site.     

Electrochemistry of molecular imprinting of large entities

Molecularly imprinted polymer (MIP) is a well-known approach, in which cavities with specific affinity are formed. These functional materials are used mostly for the separation, sensing, and catalysis of small molecules. In the last two decades, the MIP concept has been expanded for the imprinting of large entities such as nanoparticles, viruses, and cells. In this emerging field termed surface imprinted polymers (SIPs), a thin matrix imprints only part of the entity to enable its easy removal and rebinding.In this review, we focus on the different recent imprinting strategies for nanoparticles, viruses, and cells in conjunction with electrochemistry and describe their applications in the fields of biology, analytical chemistry, and medicine.     

分子印迹技术在蛋白质识别中的应用进展

分子印迹技术是一种制备具有分子识别能力的聚合物的有效技术,已经广泛应用于制备对小分子具有选择性的分子印迹聚合物,但制备能够特异性识别生物大分子--蛋白质的分子印迹聚合物的研究仍然具有挑战性。本文讨论了制备蛋白质分子印迹聚合物的难点,评述了目前印迹蛋白质的方法及各自的优缺点,展望了蛋白质印迹技术的发展趋势。     

顺二醇类生物分子的硼亲和分子印迹研究进展EI北大核心CSCD

含顺二酚的分子,如糖类、糖苷和糖蛋白等,在糖组学、代谢组学和蛋白质组学等不同领域都有着至关重要的作用。但是这类样品分子通常存在于非常低丰度的环境中且与许多干扰化合物共存,给临床和生物学上的分离检测带来了巨大的困难。因此,开发建立对顺二醇类化合物简单高效的分离方法具有重要意义。分子印迹技术,是基于模拟生物体内抗原与抗体相互作用原理而发展起来的一种新兴技术,近年来因其特定的分子识别能力以及材料的稳定性和重复性而引起了广泛关注,也在顺二醇类化合物的分离方面得到了许多应用。本综述总结了在顺二醇类化合物的分子印迹方面的最新进展,并对其未来发展的方向和前景进行了讨论。     

Biotin-specific synthetic receptors prepared using molecular imprinting

The composition of new molecularly imprinted polymers (MIPs) specific for biotin was optimised using molecular modelling software. Three functional monomers: methacrylic acid (MAA), 2-(trifluoromethyl)acrylic acid (TFAA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPSA), which demonstrated the highest binding scores with biotin, were tested on their ability to generate specific binding sites. The imprinted polymers were photografted to the surface of polystyrene microspheres in water. The affinity of the synthetic “receptor” sites was evaluated in binding experiments using horseradish peroxidase-labelled biotin. Good correlation was found between the modelling results and the performance of the materials in the template re-binding study. The dissociation constants for all MIPs were 1.4-16.8 nM, which is sufficient for most analytical applications where biotin is used as a label.     

绿色分子印迹技术简论

解析了绿色分子印迹技术(GMIT)的概念;结合水相和其他新型分子印迹技术、聚合物辅助设计及新型原材料的发展,简要阐述GMIT的发展动向.指出在绿色化学日益深入人心的今天,有必要深入探索和发展绿色分子印迹技术,从而拓展分子印迹技术研究领域、促进绿色化学的发展.     

Approaches to molecular imprinting based selectivity in capillary electrochromatography

The work done during the past decade in order to adapt molecularly imprinted polymers (MIPs) to the capillary format and subsequently use these highly selective matrices for capillary electrochromatography (CEC) are reviewed in this article. MIPs are prepared utilizing a templated polymer synthesis where the template addresses the selectivity of the resulting polymer. These polymers possess binding characteristics that are comparable to the biological antibodies. Due to the polyclonality of the binding sites in the MIP, the separation result in severe peak broadening and tailing when performed in the isocratic mode. This was seen early in the development of MIPs as selective stationary phases in liquid chromatography (LC). As a mean of decreasing these problems, much effort was put into adapting the MIP to fit in CEC systems, that offers an efficiency that is superior to that in LC. Aiming to increase the efficiency of the MIP-CEC systems, different MIP formats have been developed that can be divided into three conceptually different categories, i.e., the monolithic, the microparticle and the coating. The strive for MIP formats that can be used in small bore capillaries has led to the development of MIP formats applicable to miniaturized systems approaching the chip format. Although prepared in order to perform MIP-CEC mediated separations, these formats can be used in a broad range of applications were the characteristics of the MIP, e.g. stability, selectivity and cost efficiency, could offer an interesting solution to cover the needs.