冬凌草甲素分子印迹聚合物的制备及分子识别性能研究

以抗肿瘤药物分子冬凌草甲素为模板,甲基丙烯酸(MAA)为功能单体,乙二醇二甲基丙烯酸酯(ED-MA)作交联剂,采用沉淀聚合法和本体聚合法,制备对冬凌草甲素具有特定亲和选择性的分子印迹聚合物,并用激光粒度扫描和扫描电镜对聚合物的粒径和表面形貌进行了表征,采用平衡结合实验评价了两类分子印迹聚合物的吸附性能.结果表明,与使用...     

Investigation of protein imprinting in hydrogel-based molecularly imprinted polymers (HydroMIPs)

We have developed a strategy to produce molecularly imprinted polymers based on polyacrylamide hydrogels for the selective imprinting of bovine haemoglobin (BHb). For the first time, we have explored in detail a variety of template removal strategies including varying ratios of sodium dodecylsulphate:acetic acid (SDS:AcOH) and also the use of a trypsin digest. The optimum ratio of SDS:AcOH was found to be a 10% (w/v):10% (v/v) for the most effective template removal. This resulted in >90% (imprinting efficiency) of re-loaded template (protein) molecule being selectively bound within the MIP. At 15%:15% of SDS:AcOH, although there was even more initial template removal, subsequent re-binding studies showed a decrease in imprinting efficiency (67.9%). Trypsin solutions were also used as a method of template removal. Up to 87.4% of template was reproducibly removed initially; however, the imprinting efficiency was only 20.4%. The high selectivity of the BHb HydroMIP to BHb compared with other structural analogues (namely cytochrome C and myoglobin) was successfully demonstrated.     

Signaling molecularly imprinted polymers: molecular recognition-based sensing materials

Molecular imprinting is a template polymerization technique that can easily provide synthetic polymers capable of molecular recognition for given target molecules. In addition to their highly specific recognition ability, we are attempting to introduce signaling functions to molecularly imprinted polymers, enabling them to respond according to specific binding events. Some of our work regarding such signaling molecularly imprinted polymers is presented here, including molecularly imprinted polymers that induce spectral shifts of target compounds because of binding. Such compounds include hydrogen-bonding-based fluorescent imprinted polymers and metalloporphyrin-based signaling molecularly imprinted polymers.     

Syntheses of steroid-based molecularly imprinted polymers and their molecular recognition study with spectrometric detection

Recognition of five steroid compounds, beta-estradiol, ethynylestradiol, estradiolbenzoate, testosterone and methyltestosterone were studied using a synthesized molecularly imprinted polymer (MIP). When beta-estradiol was used as the template molecule, the polymer was synthesized with methacrylic acid (MAA) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the cross linking agent through non-covalent interactions. It is found that the kind of porogen solvent and the polymerization conditions greatly affected the binding ability of a MIP to a certain molecule. Releasing of the template was performed by continuous extraction with methanol containing 10% acetic acid in a Soxhlet extractor. Our results indicated that such carefully synthesized MIP showed specific affinity toward beta-estradiol in the adsorption process.     

Chromatographic characterization of molecularly imprinted polymers

Recent efforts in the investigation of chromatographic characterization of molecularly imprinted polymers (MIPs) have focused mainly on the nature of heterogeneous binding sites. More data on the thermodynamics than on the kinetic features of MIP columns have been published. The present article addresses the sources of peak broadening and tailing, which are the main drawbacks often associated with imprinted polymers in chromatography for practical applications. With use of the theory of nonlinear chromatography, the peak properties of a MIP column, including the retention and peak broadening and tailing, can be well interpreted. Efforts to improve chromatographic efficiency using MIPs prepared by approaches different from the conventional method, including covalent imprinting and the format of uniformly sized spherical microbeads, are reviewed and discussed. This review leads to the conclusion that nonlinear chromatography theory is useful for characterizing chromatographic features of MIP columns, since a MIP is essentially an affinity-based chromatographic stationary phase. We expect more theoretical and experimental studies on the kinetic aspects of MIP columns, especially the factors influencing the apparent rate constant, as well as the analysis of the influences of mobile-phase composition on the chromatographic performance. In addition to revealing the affinity interaction by molecular recognition, slow nonspecific interactions which may be inherited from the imperfect imprinting and may be involved in the rebinding of the template to MIPs also need to be characterized. Figure The peak broadening and tailing associated often with molecularly imprinted polymers (MIPs) in column chromatography for practical applications can be well characterized by the theory of nonlinear chromatography.     

Influence of intramolecular hydrogen bond of templates on molecular recognition of molecularly imprinted polymers

Three molecularly imprinted polymers (MIPs) were prepared corresponding to three structurally related template compounds 4-hydroxybenzoic acid (4-HBA), gentisic acid (GA) and salicylic acid (SA) that differ in intramolecular hydrogen bonding ability using acrylamide (AA) as a functional monomer. HPLC method was used to evaluate the binding performances of the MIPs to the templates and several analogues. The results showed that the difference in their molecular recognition ability was pronounced. The highest molecular recognition ability was observed for 4-HBA-imprinted polymer. It was proved that the hydrogen bond interaction between the functional monomer and the template (4-HBA) played a major role in the recognition process and Scatchard analysis showed that two classes of binding sites were formed in 4-HBA-imprinted polymer. Their dissociation constants were estimated to be 1.76×10⁻⁴ and 1.40×10⁻³ mol l⁻¹, respectively. But for GA- or SA-imprinted polymer the molecular recognition ability was not improved compared to the blank polymer (BP). By comparison of the structures of the three templates, it was concluded that the molecular recognition ability will decrease when the template itself is able to form intramolecular hydrogen bond in the molecular imprinting process. This study will be helpful for us to understand the molecular recognition mechanism of MIPs and of instructive significance for the prediction of the selectivity of MIPs.     

Comparison of binding behavior for molecularly imprinted polymers prepared by hierarchical imprinting or Pickering emulsion polymerization

The aim of this study was the evaluation of the binding performances and selectivity of molecularly imprinted beads prepared toward several penicillins (i) by hierarchical bulk polymerization in the pores of template‐grafted silica microbeads (hMIPs) and (ii) by Pickering emulsion polymerization in the presence of template‐decorated silica nanobeads (pMIPs). 6‐Aminopenicillanic acid was chosen as the common fragmental mimic template. Both approaches produced micron‐sized polymeric beads with good recognition properties toward the target ligands whereas the selectivity pattern appeared quite different. The polymer prepared by the Pickering emulsion approach showed binding properties similar to imprinted beads prepared by hierarchical approach. Equilibrium binding constants changed their values from 0.1–0.2 × 10⁶ (hMIPs) to 0.2–0.6 × 10⁶ M^?1 (pMIPs), while the binding site densities changed from 3.7–4.8 (hMIPs) to 0.3–0.55 μmol/g (pMIPs). Compared to the hierarchical polymerization, Pickering emulsion polymerization represents a more practical approach when a template mimic needs to be used.     

Dopamine sensor based on molecularly imprinted electrosynthesized polymers

Molecularly imprinted polymers (MIPs) have been applied as molecular recognition elements to chemical sensors. In this paper, we combined the use of MIPs and electropolymerization to produce a sensor which was capable of detecting dopamine (DA). The MIP electrode was obtained by electrocopolymerization of o-phenylenediamine and resorcinol in the presence of the template molecular DA. The MIP electrode exhibited a much higher current response compared with the non-imprinted electrode. The response of the imprinted sensor to DA was linearly proportional to its concentration over the range 5.0 × 10⁻⁷-4.0 × 10⁻⁵ M. The detection limit of DA is 0.13 μM (S/N = 3). Moreover, the proposed method could discriminate between DA and its analogs, such as ascorbic acid and uric acid. This method was successfully applied to the determination of DA in dopamine hydrochloride injection and healthy human blood serum. These results revealed that such a sensor fulfilled the selectivity, sensitivity, sped, and simplicity requirements for DA detection and provided possibilities of clinical application in physiological fields.     

基于磁性分子印迹聚合物的电化学传感器的研究进展

分子印迹聚合物与磁性纳米材料结合,制备成磁性分子印迹纳米敏感膜,这样做不仅可以发挥分子印迹聚合材料的优势,而且磁性纳米粒子可有效提高电化学传感器的灵敏度、稳定性以及生物相容性等.近年来将磁性分子印迹纳米敏感膜应用于电化学传感器制备成的磁性分子印迹电化学传感器得到了较快的发展.本文就近5年来磁性分子印迹电化学传感器敏感膜...     

一种亲水性印迹聚合物的性能研究

本文以甲砜霉素为模板分子,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,偶氮二异丁腈为引发剂,环氧氯丙烷为亲水调节剂,采用沉淀聚合法制备亲水性开环分子印迹聚合物(OC-HMIP),对其进行静态平衡吸附实验、Scatchard分析、色谱评价。结果表明,制备的OC-HMIP具有较大的吸附能力,良好的特异识别性,能够在水相中很好的分离模板分子及其结构类似物。另外又对制备出的聚合物进行了亲水性能测定,结果表明OC-HMIP的亲水性能显著提高。     

Carbohydrate recognition by porphyrin-based molecularly imprinted polymers

[structure: see text] Porphyrin-based molecularly imprinted polymers (MIPs) were prepared for carbohydrate recognition. A urea-appended porphyrin functional monomer was utilized to provide complementary functionality and quality binding sites throughout the polymer. Each porphyrin-based polymer demonstrates high affinity and differential selectivity for closely related carbohydrates that correlate to the structure of the template used in the imprinting process.     

Selective sample treatment using molecularly imprinted polymers

The molecularly imprinted polymers (MIPs) are synthetic polymers possessing specific cavities designed for a target molecule. By a mechanism of molecular recognition, the MIPs are used as selective sorbents for the solid-phase extraction of target analytes from complex matrices. MIPs are often called synthetic antibodies in comparison with immuno-based sorbents; they offer some advantages including easy, cheap and rapid preparation and high thermal and chemical stability. This review describes the use of MIPs in solid-phase extraction with emphasis on their synthesis, the various parameters affecting the selectivity of the extraction, their potential to selectively extract analytes from complex aqueous samples or organic extracts, their on-line coupling with LC and their potential in miniaturized devices.     

Citrinin selective molecularly imprinted polymers for SPE

Molecularly imprinted polymers (MIPs) for citrinin (Cit) with 1‐hydroxy‐2‐naphthoic acid (HNA) as mimic template were prepared and the molecularly imprinted SPE method was developed for the detection of Cit in rice with HPLC. The adsorption properties of HNA and Cit on the MIPs and nonimprinted polymers were investigated. It proved that MIPs showed higher selectivity adsorption to HNA and Cit than nonimprinted polymers were. The recoveries of Cit in rice were in the range of 86.7–97.7%. The spiked rice samples and five rice samples in Beijing market were detected using molecularly imprinted SPE method and satisfied results were obtained as discussed in this article.     

Preparing molecularly imprinted nanoparticles of saponins via cooperative imprinting strategy

Saponin is an important class of natural products with various pharmacological activities. The selective separation of saponins is an essential step before further analysis. Molecular imprinting has been an effective strategy for preparing antibody mimics. However, a facile and efficient imprinting strategy for saponins is still lacking owing to their amphiphilic nature. Herein, we have prepared the saponins imprinted nanoparticles via cooperative imprinting strategy. This new strategy relies on the combination of various non‐covalent interactions (hydrophobic and hydrogen bonding) and covalent boronate affinity interactions. The obtained imprinted nanoparticles could rebind specific saponins from complex matrices with good selectivity, superb tolerance to interference, and fast binding equilibrium. This method was verified to be versatile and facile. Thus, this strategy could greatly facilitate the preparation of imprinted nanoparticles for the specific recognition of saponins.     

Towards ochratoxin A selective molecularly imprinted polymers for solid-phase extraction

Molecularly imprinted polymers (MIPs) displaying selective binding properties for the mycotoxin ochratoxin A (OTA) in polar/protic media were prepared. Crucial to the success of these efforts was the implementation of rationally designed OTA mimics as templates and a set of novel basic and neutral functional monomers, allowing the maximization of the template-functional monomer association via ion-pairing, hydrophobic and steric interactions. MIPs prepared with a 20:1:1:3 molar ratio of cross-linking agent, template mimic, basic functional monomer and hydrophobic auxiliary monomer produced polymers with superior recognition properties compared to materials generated with other stoichiometries. Chromatographic evaluation using the OTA mimics, OTA and a set of structurally closely related compounds as analytes revealed pronounced substrate selectivity of these MIPs in polar/protic media, the templates and OTA being bound with significantly higher affinities. Complementary substrate selectivities/affinities were observed in aprotic and apolar solvents. The possibility of solvent-dependent tuning of substrate selectivity/affinity and the high binding capacity recommend the developed MIPs as promising solid-phase extraction adsorbents for clean-up and pre-concentration of OTA from various biologically relevant matrices.     

New configurations and applications of molecularly imprinted polymers

Molecularly imprinted polymers (MIPs) are applicable in a variety of different configurations. For example, bulk polymers imprinted with beta-lactam antibiotics are presented to be used as stationary phases for the chromatographic separation of beta-lactam antibiotics with both aqueous and organic mobile phases. However, in some analytical applications, monosized spherical beads are preferred over the currently used ground bulk polymers. A precipitation polymerization technique allows preparation of monosized spherical imprinted beads with diameters down to 200 nm having excellent recognition properties for different target molecules. Nevertheless, with current imprinting protocols a substantial amount of template has to be used to prepare the polymer. This can be problematic if the template is poorly soluble, expensive or difficult to obtain. It is shown that for analytical applications, the functional monomer:template ratio can be drastically increased without jeopardizing the polymer's recognition properties. Furthermore, a substantial reduction of the degree of crosslinking is demonstrated, resulting in much more flexible polymers that are useful for example the preparation of thin imprinted films and membranes for sensors. Apart from analysis, MIPs also are applicable in chemical or enzymatic synthesis. For example, MIPs using the product of an enzyme reaction as template are utilized for assisting the synthetic reaction by continuously removing the product from the bulk solution by complexation. This results in an equilibrium shift towards product formation.     

L-酪氨酸印迹分子的制备及性能研究

利用分子印迹技术采用传统加热法制备出酪氨酸他子印迹聚合物。用红外光谱分析了聚合物结构。研究了印迹他子与功能单体的物质的量对聚合物结合性的影响,吸收效率表征结果显示,与化学组成相同的空白聚合物相比,印迹聚合物具有更高的吸附效率。     

Catalysis of benzisoxazole isomerization by molecularly imprinted polymers

A tailor-made catalytically active polymer catalyzing the benzisoxazole isomerization is described. Kinetic studies carried out in water/ethanol (3:1, v/v) at room temperature, showed a rate acceleration (k_MIP/k_control) of 7.2-fold compared to the control polymer. The imprinted polymer exhibits Michaelis-Menten kinetics with a K_m of 0.484 mM and a k_cat of 0.205 min⁻¹. Compared with the uncatalyzed reaction, a rate enhancement ((k_cat/K_m)/k_uncat) of 4 × 10⁴ fold was obtained. Substrate selectivity, accessible binding site analysis, dissociation constant determination, and inhibition study were also performed.