Liquid crystal polysiloxane networks as materials for molecular imprinting technology: memory of the mesomorphic organization

A novel approach to the synthesis of molecularly imprinted polymers via non-covalent linkages has been studied. It relies on the use of thermotropic side group liquid crystal polymer networks. The polysiloxane networks obtained after extraction of the template preserved the mesomorphic organization set up in the presence of the guest molecule. A first batch rebinding analysis was performed: this study revealed that the imprinted polymer has a much greater affinity for the template molecule than has the non-imprinted polymer, and a significant selectivity.     

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.     

Nanocomposite of bimetallic nanodendrite and reduced graphene oxide as a novel platform for molecular imprinting technology

In this present work, for the first time, we are reporting a green synthesis approach for the preparation of vinyl modified reduced graphene oxide-based magnetic and bimetallic (Fe/Ag) nanodendrite (RGO@BMNDs). Herein, the RGO@BMNDs acts as a platform for the synthesis of the pyrazinamide (PZA)-imprinted polymer matrix and used for designing of the electrochemical sensor. We have demonstrated how the change in morphology could affect the electrochemical and magnetic property of nanomaterials and for this the reduced graphene oxide-based bimetallic nanoparticle (Fe/Ag) was also prepared It was found that the combination of graphene and bimetallic nanodendrites shows improvement as well as enhancement in the electrocatalytic activity and adsorption capacity, in comparison to their respective nanoparticles. The application of imprinted-RGO@BMNDs sensor was explored for trace level detection of PZA (Limit of detection = 6.65 pg L⁻¹, S/N = 3), which is a drug used for the cure of Tuberculosis. This is lowest detection limit reported so far for the detection of PZA. The sensor is highly selective, cost-effective, simple and free from any interfering effect. The real time application of the sensor was explored by successful detection of PZA in pharmaceutical and human blood serum, plasma and urine samples.     

Liquid crystal tetramers: influence of molecular shape on liquid crystal behaviour

The synthesis and characterization of two homologous series of tetramers in which four mesogenic units are linked via three alkyl spacers are reported. Both series contain a hexamethylene central spacer while the length of the two outer spacers, n, is varied from three to 12 methylene units. The two series differ only in the substitution pattern around the inner two mesogenic units. The series in which one mesogenic unit is attached to the central spacer in the 4-position while the other is connected at the 3-position is referred to as the n-p6m-n series, while in the n-m6m-n series both inner units are attached in the 3-position. All the members of the n-p6m-n series exhibited a nematic phase while no liquid crystallinity was observed for the n-m6m-n series. The thermal behaviour of this series is compared with that of the n-p6p-n series and also with that of the corresponding series containing a pentamethylene central spacer. The trends observed are interpreted in terms of the average molecular shapes of these tetramers.     

分子印迹技术在蛋白质分离分析中的研究进展

蛋白质结构复杂,种类多样,与各种生命活动密切相关。大部分蛋白质在生物体中含量极低,对其分析检测带来极大困难。因此实现复杂生物样品中蛋白质的选择性识别与分离,对实现蛋白质的分离分析意义重大。通过分子印迹技术制备的分子印迹聚合物含有与模板分子大小、形状一致,官能团相互匹配的三维印迹空穴,在蛋白质的选择性识别与分离领域显示出了巨大的发展潜力。但是,由于蛋白质具有尺寸较大、构型易变、结构复杂等特点,分子印迹技术在蛋白质印迹中面临着巨大挑战。该文在介绍几种新型分子印迹技术包括表面印迹、抗原决定基印迹和金属螯合物印迹的基础上,综述了近3年分子印迹技术在蛋白质分离分析方面的应用,并对其发展进行了总结与展望。     

Recognition of proteins and peptides: Rational development of molecular imprinting technology

The creation of tailor-made receptors which are able to recognize molecular targets with high affinity and selectivity has attracted much attention in the field of chemistry, physics, and biology. Molecular imprinting has proved to be an effective technique for generating specific recognition sites in synthetic polymers. The synthesis of molecular imprinted polymers specific for proteins and peptides has been a focus for many scientists working in the area of molecular recognition, since the creation of synthetic polymers that can specifically recognize biomacromolecules is a very challenging but potentially extremely rewarding work. These polymers with specificity for biological macromolecules have considerable potential for applications in the areas of solid phase extraction, catalysis, medicine, clinical analysis, drug delivery, environmental monitoring, and sensors. In this review, the authors discuss the developed approaches associated with the imprinting of peptides and proteins, and provide an overview of the significant progress achieved within this field. Finally, the possible mechanism of the molecular imprinting and recognition has been discussed.     

Hybrid sol–gel silica adsorbent materials synthesized by molecular imprinting for tannin removal

Journal of Sol-Gel Science and Technology - This study reports the development of a functional adsorbent synthesized by the molecular imprinting method in a sol–gel matrix. The adsorption...     

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。     

Recent advances in molecular imprinting technology: current status, challenges and highlighted applications

Molecular imprinting technology (MIT) concerns formation of selective sites in a polymer matrix with the memory of a template. Recently, molecularly imprinted polymers (MIPs) have aroused extensive attention and been widely applied in many fields, such as solid-phase extraction, chemical sensors and artificial antibodies owing to their desired selectivity, physical robustness, thermal stability, as well as low cost and easy preparation. With the rapid development of MIT as a research hotspot, it faces a number of challenges, involving biological macromolecule imprinting, heterogeneous binding sites, template leakage, incompatibility with aqueous media, low binding capacity and slow mass transfer, which restricts its applications in various aspects. This critical review briefly reviews the current status of MIT, particular emphasis on significant progresses of novel imprinting methods, some challenges and effective strategies for MIT, and highlighted applications of MIPs. Finally, some significant attempts in further developing MIT are also proposed (236 references).     

Preparation of a new type of affinity materials combining metal coordination with molecular imprinting

A new approach, combining metal-coordination with molecular imprinting technology, was developed to prepare protein-affinity materials, which showed higher specific recognition ability towards the target protein than those prepared using either metal-coordination or molecular imprinting technology.     

Metallophthalocyanine-based molecular materials as catalysts for electrochemical reactions

Metallophthalocyanines confined on the surface of electrodes are active catalysts for a large variety of electrochemical reactions and electrode surfaces modified by these complexes can be obtained by simple adsorption on graphite and carbon. However, more stable electrodes can be achieved by coating their surfaces with electropolymerized layers of the complexes, that show similar activity than their monomer counterparts. In all cases, fundamental studies carried out with adsorbed layers of these complexes have shown that the redox potential is a very good reactivity index for predicting the catalytic activity of the complexes. Volcano-shaped correlations have been found between the electrocatalytic activity (as log I at constant E) versus the Co(II)/(I) formal potential (E°′) of Co-macrocyclics for the oxidation of several thiols, hydrazine and glucose. For the electroreduction of O₂ only linear correlations between the electrocatalytic activity versus the M(III)/M(II) formal potential have been found using Cr, Mn, Fe and Co phthalocyanines but it is likely that these correlations are “incomplete volcano” correlations. The volcano correlations strongly suggest that E°′, the formal potential of the complex needs to be in a rather narrow potential window for achieving maximum activity, probably corresponding to surface coverages of an M-molecule adduct equal to 0.5 and to standard free energies of adsorption of the reacting molecule on the complex active site equal to zero. These results indicate that the catalytic activity of metallophthalocyanines for the oxidation of several molecules can be “tuned” by manipulating the E°′ formal potential, using proper groups on the macrocyclic ligand. This review emphasizes once more that metallophthalocyanines are extremely versatile materials with many applications in electrocatalysis, electroanalysis, just to mention a few, and they provide very good models for testing their catalytic activity for several reactions. Even though the earlier applications of these complexes were focused on providing active materials for electroreduction of O₂, for making active cathodes for fuel cells, the main trend in the literature nowadays is to use these complexes for making active electrodes for electrochemical sensors.     

Selective silica‐based sorbent materials synthesized by molecular imprinting for adsorption of pharmaceuticals in aqueous matrices

The presence of pharmaceuticals in aqueous environmental matrices often requires efficient and selective preconcentration procedures. Thus, silicas (SILs) were synthesized by a molecular imprinting technique using an acid‐catalyzed sol‐gel process and the following drugs as templates: fluoxetine, gentamicin, lidocaine, morphine, nifedipine, paracetamol, and tetracycline. The materials were subjected to sorbent extraction assisted by ultrasonic treatment to remove the drugs and the consequent formation of molecular imprinted cavities. The surface area of the resulting materials ranged from 290 to 960 m²/g. Adsorption tests were performed with the molecular imprinting phases. In terms of the potential selectivity, the SILs were subjected to the adsorption of drugs from samples such as potable and surface water. The adsorption capacity remained in the range between 55 and 65% for both matrices, while for the nonimprinted SIL it remained between 15 and 20%.     

分子印迹技术在天然产物有效成分分离纯化中的应用

天然产物体系复杂,大分子和小分子、生命和非生命物质共存,多存在结构相近的异构体,且有效成分含量低,采用一般的分离方法富集难度较大。分子印迹技术是制备高选择性分离介质的有效技术手段,分子印迹聚合物(MIP)的选择性强,分离操作简单,在各种分离纯化中展现了良好的应用前景。本文对近年来分子印迹技术在天然产物活性组分(如生物碱、甾体、多元酚、黄酮等)的分离纯化中的应用进行了综述,并介绍了本课题组利用MIP从天然产物中分离纯化莽草酸等活性成分的研究进展。     

Surface molecular imprinting for chemiluminescence detection of the organophosphate pesticide chlorpyrifos

We report on a surface molecular imprinting strategy for synthesizing core-shell particles whose shell is imprinted with chlorpyrifos (CPF). The particles were prepared by copolymerization of the methacryloyl groups on the surface of silica particles modified with 3-methacryloxypropyl trimethoxysilane a functional monomer and a cross-linking agent. The imprinted particles exhibit larger binding capacity, faster binding kinetics, and higher recognition selectivity for CPF. Combined with highly sensitive chemiluminescence assay, the method was applied to the determination of CPF with a detection limit of 0.92?nM which is about 2 orders of magnitude lower than that by conventional CL method. The method also displays repeatability for more than 200 times.

New indole trimers as precursors for molecular electronic materials

We have prepared two new C₃-symmetric, substituted-triazatruxene molecules using a facile one-pot trimerisation of 5-carboxyindole and 6-bromoindole in acetic acid using Br₂, giving 2a and 3a, respectively. These were subsequently modified by the addition of six alkyl chains to the N- and carboxyl-positions of 2a giving 2b and three alkyl chains to the N-positions of 3a giving 3b. The new molecules were characterised using cyclic voltammetry, UV/vis and emission spectroscopy, DFT calculations and in the case of 3b, field-effect transistor measurements showing gate-modulated source-drain current. These represent a straightforward route to large polyaromatic molecules with easily-modified side groups and are suitable as building blocks for synthesis of functional molecules for materials.     

Synthesis and properties of molecular imprints of darifenacin: The potential of molecular imprinting for bioanalysis

Summary A molecularly imprinted polymer has been developed which subsequently demonstrated an ability to selectively retain darifenacin (UK-88, 525-S) from aqueous acetonitrile when used as a stationary phase in HPLC columns and as a packing in solid-phase extraction cartridges. The imprinted polymer is applicable to a wide range of analytical methods including extraction from plasma, purification of radiolabelled UK-88,525, chiral separations and separation of metabolites and structural analogues. The polymer is able to extract darifenacin directly from a protein-precipitated human plasma/acetonitrile (1:1 v/v) mixture with 100% recovery. The imprinted polymer can also effect a repurification of¹⁴C-labelled darifenacin. The drawbacks of molecular imprints for ultra-trace bioanalysis (in the sub-nanogram/mL range) are discussed. These centre on the difficulty of removing all the template from the polymer and the consequent effects of template bleed on assay precision and accuracy when used as solid-phase extraction cartridges. Possible solutions to this problem are considered. Presented at: Affinity Chromatography Conference, Cambridge, UK, July 1–3, 1997.     

Urea host monomers for stoichiometric molecular imprinting of oxyanions

A series of urea-based vinyl monomers was synthesized and investigated for their ability to function as polymerizable hosts for the molecular imprinting of N-Z-D- or L-glutamic acid in polar media (DMSO or DMF). The monomers were synthesized in one step from a polymerizable isocyanate and a nonpolymerizable amine or vice versa, with yields typically over 70%. Prior to polymerization their solution binding properties vis-a-vis tetrabutylammonium benzoate in DMSO were investigated by 1H NMR, UV-vis and fluorescence monitored titrations. The affinities of the urea monomers for benzoate depended upon the substitution pattern of the urea, with all diaryl ureas exhibiting high affinity. EDMA-based imprinted polymers prepared in DMF or DMSO against Z-D-(or L)-glutamic acid using 2 equiv of the urea monomer and 2 equiv of base were able to recognize the imprinted dianion as well as larger molecules containing the glutamic acid substructure. The affinity, reflected in liquid chromatography retention data, correlated with the solution binding properties of the corresponding monomers.