Bulk acoustic wave sensor using molecularly imprinted polymers as recognition elements for the determination of pyrimethamine

A new bulk acoustic wave (BAW) sensor modified with a molecularly imprinted polymer (MIP) was fabricated and applied for the determination of pyrimethamine. This sensor exhibited high selectivity and sensitive response to pyrimethamine. Factors such as pH and the amount of coating influencing sensor properties, were investigated in detail and optimized. The calibration curve was linear in the range 6.0x10(-7)-1.0x10(-4) M. The determination limit was 2.0x10(-7) M. In harsh chemical environments such as high temperature, organic solvents, bases, acids, etc., the sensor still exhibited long-term stability. The proposed method has been satisfactorily applied for the determination of pyrimethamine in serum and urine media.     

Flow chemiluminescence sensor for determination of clenbuterol based on molecularly imprinted polymer

In this paper, a novel flow chemiluminescence (CL) clenbuterol sensor based on molecularly imprinted polymer (MIP) on line enrichment nanogram clenbuterol and chemiluminescence reaction of potassium permanganate and formaldehyde in the polyphosphate enhanced by clenbuterol. Clenbuterol in the urine was selectively adsorbed on the clenbuterol-imprinted polymer, which was packed into the flow cell. The formaldehyde and the polyphosphate with potassium permanganate flowed through the flow cell and reacted with the on line adsorbed clenbuterol and produced strong CL. The results show that the sensor was reversible. The CL intensity was linear with clenbuterol concentration from 1.0 × 10⁻⁹ g/mL to 5.0 × 10⁻⁸ g/mL. The detection limit was 3.0 × 10⁻¹⁰ g/mL. The R.S.D. for ng/mL clenbuterol was less than 5% (n = 3). The present method offered a high selectivity and sensitivity that made the quantitative analysis of trace clenbuterol (ng/mL) in the animal urine sample.     

基于分子印迹技术的丙溴磷压电石英晶体微天平研制

介绍了一种用于检测丙溴磷农药的分子印迹压电生物传感器的构建方法。采用沉淀聚合法合成了农药丙溴磷的分子印迹聚合物,将其固定于石英晶体微天平电极表面构建传感器;采用环境扫描电镜以及原子力显微镜对聚合物形貌、传感器电极表面形貌特征进行分析,并利用传感器对丙溴磷农药进行检测分析,其质量浓度在10~1000 ng/mL范围内,传感器频率改变与丙溴磷浓度之间的响应呈线性关系,线性方程为y=0.139ρ+2.26(r=0.9984)。结果表明,构建的分子印迹压电生物传感器能够对农药进行初步检测,具有较高的灵敏性和较好的特异识别能力。     

Electrochemical sensor for 2,4-dichlorophenoxy acetic acid using molecularly imprinted polypyrrole membrane as recognition element

An electrochemical sensor based on molecularly imprinted polypyrrole membranes is reported for the determination of 2,4-dichlorophenoxy acetic acid (2,4-D). The sensor was prepared by electropolymerization of pyrrole on a glassy carbon electrode in the presence of 2,4-D as a template. The template was removed by overoxidation at +1.3 V in buffer solution. The sensor can effectively improve the reductive properties of 2,4-D and eliminate interferences by other pesticides and electroactive species. The peak current at -0.78 V is linear with the concentration of 2,4-D from 1.0 to 10 µM, the detection limit is 0.83 µM (at 3σ), and the relative standard deviation is 3.9% (at 5.0 µM of 2,4-D; n?=?7). The method has been successfully applied to the determination of 2,4-D in environmental water samples, with recovery rates ranging from 92% to 108%.     

Piezoelectric quartz crystal sensor for rapid analysis of pirimicarb residues using molecularly imprinted polymers as recognition elements

A new piezoelectric quartz crystal (PQC) sensor using molecularly imprinted polymer (MIP) as sensing material has been developed for fast and onsite determination of pirimicarb in contaminated vegetables. Three MIPs particles have been prepared by conventional bulk polymerization (MIP-B) and precipitation polymerization in either acetonitrile (MIP-P1) or chloroform (MIP-P2). MIP-P2, with uniform spherical shape and mean diameter at about 50 nm, has shown the best performance as the sensing material for PQC sensor. The sensor fabricated with MIP-P2 can achieve a steady-state response within 5 min, a very short response time as compared to MIPs-coated PQC sensor reported in the literature. The sensor developed exhibits good selectivity (low response to those pesticides with similar structures to pirimicarb, such as atrazine, carbaryl, carbofuran and aldicarb) and high sensitivity to pirimicarb with a linear working range from 5.0 × 10⁻⁶ to 4.7 × 10⁻³ mol L⁻¹ (following a regression equation (r = 0.9988) of −ΔF = 0.552 + 1.79 × 10⁶ C), a repeatability (R.S.D., n = 5) of 4.3% and a detection limit (S/N = 3, n = 5) of 5 × 10⁻⁷ mol L⁻¹. The MIP-coated PQC sensor developed is shown to provide a sensitive and fast method for onsite determination of pirimicarb in aqueous extract from contaminated vegetables with satisfactory recoveries from 96 to 103% and repeatability (R.S.D., n = 5) from 4.6 to 7.1% at pirimicarb concentrations ranging from 8.0 × 10⁻⁶ to 2.0 × 10⁻⁴ mol L⁻¹.     

Flow injection fluorimetric determination of beta-estradiol using a molecularly imprinted polymer

The steroidal compound 17beta-estradiol (E2) is a major estrogen now widely studied because of its potential endocrine disruption effects. The present paper describes a simple, rapid, flow injection (FI) method for the fluorimetric determination of beta-estradiol involving a molecularly imprinted polymer (MIP) packed into a microcolumn. Microwave-assisted extraction, a relatively new technique, was used to help remove the template from the MIP; this improved extraction efficiency. The optimization of the FI parameters and the intrinsic fluorescence of beta-estradiol allowed its direct determination without a derivatization step. When the possible interference of other estrogens was examined, the system displayed excellent specificity for beta-estradiol; no response to the natural estrogens estrone and estriol and the xenoestrogen bisphenol A was recorded. Under optimum experimental conditions, linear calibration graphs were obtained from 4 to 80 microg L(-1) with a detection limit of 1.12 microg L(-1).     

Flow injection chemiluminescence determination of epinephrine using epinephrine-imprinted polymer as recognition material

A flow injection chemiluminescence (CL) method using epinephrine-imprinted polymer as recognition material was investigated for the determination of epinephrine. The analyte, epinephrine, was selectively and temporarily adsorbed on the epinephrine-imprinted polymer, which was packed into a flow-cell placed in front of the window of a photomultiplier tube. Afterwards, the CL reagent, the emerging stream of luminol (presence of potassium ferrocyanide) and potassium ferricyanide flowed through the flow-cell and reacted with epinephrine adsorbed on the polymer to produce strong CL. The CL intensity responded linearly to the logarithm of the concentration of epinephrine within 5.0×10⁻⁹ to 1.0×10⁻⁷ mol/l range with a detection limit of 3×10⁻⁹ mol/l. The R.S.D. for 2.0×10⁻⁸ mol/l of epinephrine solution was less than 5% (n=7). Interference experiments demonstrated that the application of molecular imprinted polymer (MIP) to CL analysis could be improved the selectivity of the method greatly. Tests of the recovery for known amount of epinephrine in serum were carried out and satisfactory results were obtained. At the same time, the binding characteristic of the polymer to epinephrine was evaluated by the batch method and the dynamic method.     

Thin-film electrochemical sensor for diphenylamine detection using molecularly imprinted polymers

This work reports on the development of a new voltammetric sensor for diphenylamine based on the use of a miniaturized gold electrode modified with a molecularly imprinted polymer recognition element. Molecularly imprinted particles were synthesized ex situ and further entrapped into a poly(3,4-ethylenedioxythiophene) polymer membrane, which was electropolymerized on the surface of the gold electrode. The thickness of the polymer layer was optimized in order to get an adequate diffusion of the target analyte and in turn to achieve an adequate charge transfer at the electrode surface. The resulting modified electrodes showed a selective response to diphenylamine and a high sensitivity compared with the bare gold electrode and the electrode modified with poly(3,4-ethylenedioxythiophene) and non-imprinted polymer particles. The sensor showed a linear range from 4.95 to 115 μM diphenylamine, a limit of detection of 3.9 μM and a good selectivity in the presence of other structurally related molecules. This sensor was successfully applied to the quantification of diphenylamine in spiked apple juice samples.     

氯丙嗪分子印迹化学发光微流控传感器芯片的研究

以氯丙嗪分子印迹聚合物为识别物质,以鲁米诺-K3Fe(CN)6化学发光体系,建立了一种新型的氯丙嗪化学发光微流控分子印迹传感器芯片的检测方法。利用二氧化碳激光在聚甲基丙烯酸甲酯材质上刻蚀出200μm宽,150μm深的微通道,8 mm长,1 mm宽,0.5 mm深的微检测池。微检测池中填充50μm粒径大小的热聚合得到的氯丙嗪分子印迹聚合物作为识别物质,在线富集氯丙嗪,富集的氯丙嗪可以增强鲁米诺和K3Fe(CN)6的化学发光强度,以化学发光强度定量氯丙嗪量。该传感器的响应值与0.02~0.4μg/mL氯丙嗪呈良好的线性关系,检出限为8 ng/mL(3σ)。该微流控传感器芯片已用于测定人尿液中的氯丙嗪。     

Flow-injection chemiluminescence sensor for determination of isoniazid in urine sample based on molecularly imprinted polymer

In this paper, molecularly imprinted polymer (MIP) of isoniazid is synthesized through thermal radical copolymerization of metharylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) in the presence of isoniazid template molecules. A novel flow injection chemiluminescence sensor for isoniazid determination is developed by packing the isoniazid-MIP into the flow cell as recognition elements. Isoniazid could be selectively adsorbed by the MIPs and the adsorbed isoniazid was sensed by its great enhancing effect on the weak CL reaction between luminol and periodate which were mixed in the flow cell. The enhanced CL intensity is linear in the range 2x10(-9) to 2x10(-7) g/mL and the detection limit is 7x10(-10) g/mL (3sigma) isoniazid with a relative standard deviation 2.8% (n=9) for 8x10(-8) g/mL. The sensor is reversible and reusable. It has a great improvement in sensitivity and selectivity for CL analysis. As a result, the sensor has been successfully applied to determination of isoniazid in human urine. At the same time, the binding characteristic of the polymer to isoniazid was evaluated by batch method and the dynamic method, respectively.     

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.     

A novel electrochemical sensor based on molecularly imprinted polymers for caffeine recognition and detection

A sensitive and selective electrochemical sensor based on molecularly imprinted polymers (MIPs) was developed for caffeine (CAF) recognition and detection. The sensor was constructed through the following steps: multiwalled carbon nanotubes and gold nanoparticles were first modified onto the glassy carbon electrode surface by potentiostatic deposition method successively. Subsequently, o-aminothiophenol (ATP) was assembled on the surface of the above electrode through Au–S bond before electropolymerization. During the assembled and electropolymerization processes, CAF was embedded into the poly(o-aminothiophenol) film through hydrogen bonding interaction between CAF and ATP, forming an MIP electrochemical sensor. The morphologies and properties of the sensor were characterized by scanning electron microscopy, cyclic voltammetry, and differential pulse voltammetry. The recognition and determination of the sensor were observed by measuring the changes of amperometric response of the oxidation-reduction probe, [Fe(CN)₆]^3?/[Fe(CN)₆]^4?, on modified electrode. The results demonstrated that the prepared sensor had excellent selectivity and high sensitivity for CAF, and the linear range was 5.0?×?10^?10?~?1.6?×?10^?7?mol?L^?1 with a detection limit of 9.0?×?10^?11?mol?L^?1 (S/N?=?3). The sensor was also successfully employed to detect CAF in tea samples.     

基于分子印迹聚合物的化学发光传感器测定尿样中的甲福明

合成了甲福明的分子印迹聚合物,以此聚合物为识别物质,在线分离富集甲福明,建立了一种测定甲福明的流动式化学发光但感器。N-溴代丁二酰亚胺(NBS)和荧光素与甲福明发生化学反应,产生强的化学发光。甲福明质量浓度在2×10-8~8×10-6g/mL范围内同发光强度成良好线性关系,方法的检出限为6×10-9g/mL,相对标准偏差小于5%(n=9)。选择性实验表明将分子印迹聚合物作为识别物质应用于化学发光分析中,能大大提高化学发光分析方法的选择性。该传感器可逆性强、稳定性好,可重复使用100次以上,已用于人体尿样中甲福明的测定。     

Selective recognition of sesamol using molecularly imprinted polymers containing magnetic wollastonite

The magnetic molecularly imprinted polymers (MMIPs) have been synthesized using piperonal molecules as dummy template and magnetic wollastonite composites as support. The resulting composites were applied to selective recognition of sesamol from aqueous solution. MMIPs were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) analysis, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). MMIPs were demonstrated with an imprinted polymer film (90-100 nm) and exhibited magnetic property (M(s) =8.60 emu/g) and thermal stability. The effective average diameter of the Fe(3) O(4) nanoparticles was about 10 nm and the thickness of magnetic film was about 160 nm. Batch mode adsorption studies were carried out to investigate the specific adsorption equilibrium, kinetics and selective recognition. The Langmuir isotherm model was fitted to the equilibrium data better than the Freundlich model, and the kinetic properties were well described by the pseudo-second-order equation. The value of E(a) in this study was 5.35 kJ/mol for MMIPs. In addition, the selective recognition experiments demonstrated that MMIPs have specific recognition ability toward sesamol.     

A chemiluminescence array sensor based on graphene-magnetite-molecularly imprinted polymers for determination of benzenediol isomers

A chemiluminescence (CL) array sensor for determination of benzenediol isomers simultaneously using the system of luminol–NaOH–H₂O₂ based on a graphene-magnetite-molecularly imprinted polymer (GM-MIP) is described. Use of graphene in the GM-MIP thus prepared is helpful to improve the adsorption capacity, while use of magnetite nanoparticles can facilitate the isolation of GM-MIP at end of their synthesis, and rendering easier the use of the polymers in the array sensor. The adsorption performance and properties were characterized. The GM-MIP was used to increase the selectivity in CL analysis. In addition, the sensor was reusable and of good selectivity and adsorption capacity. The array sensor was finally used for the determination of hydroquinone, resorcinol and catechol in waste water samples simultaneously.     

核壳结构的萘夫西林磁性分子印迹聚合物微球的制备及性能

以表面修饰双键的Fe₃O₄@SiO₂纳米颗粒为基体,以萘夫西林(nafcillin)为模板,甲基丙烯酸(MAA)为单体,乙二醇二甲基丙烯酸酯(EGDMA)为交联剂,偶氮二异丁腈(AIBN)为引发剂,采用三步升温聚合法合成了核壳结构的萘夫西林磁性分子印迹聚合物。采用傅里叶变换红外光谱仪(FT-IR)、透射电子显微镜(TEM)、X射线衍射仪(XRD)和振动样品磁强计(VSM)对制备的印迹聚合物微球进行了表征,得到的磁性印迹聚合物微球的粒径在320 nm左右,大小均匀,分散性较好,可以在外加磁场下与溶剂实现快速分离。对磁性印迹和非印迹聚合物进行了吸附性能研究,结果表明该印迹聚合物微球对模板分子具有很高的吸附容量(50.7 mg/g),特异性识别性能良好(印迹因子为2.46),有望应用于实际样品中萘夫西林残留量的富集分析。     

Supramolecular recognition of estrogens via molecularly imprinted polymers

The isolation and preconcentration of estrogens from new types of biological samples (acellular and protein-free simulated body fluid) by molecularly imprinted solid-phase extraction has been described. In this technique, supramolecular receptors, namely molecularly imprinted polymers (MIPs) are used as a sorbent material. The recognition sites of MIPs were prepared by non-covalent multiple interactions and formed with the target 17β-estradiol as a template molecule. High-performance liquid chromatography with spectroscopic UV, selective, and a sensitive electrochemical CoulArray detector was used for the determination of 17β-estradiol, estrone, and estriol in simulated body fluid which mimicked human plasma.     

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.     

Preparation of hydrophilic molecularly imprinted polymers for tetracycline antibiotics recognition

Hydrophilic molecularly imprinted polymers(MIPs) were prepared using tetracycline as template,methacrylic acid as monomer and glycidilmethacrylate as pro-hydrophilic co-monomer.Compared with common MIPs,the imprinting effect and adsorption amounts of hydrophilic MIPs for tetracycline(TC) were greatly improved in water media.Furthermore,the electrochemical sensor fabricated by modifying hydrophilic MIPs on glassy carbon electrode was developed for the determination of TC in foodstuff samples.     

分子印迹化学发光传感器在线检测牛肉与鸡肉组织中残留的磺胺嘧啶

以分子印迹作为识别体,制成高灵敏度和高选择性的化学发光传感器在线检测牛肉与鸡肉组织中残留的磺胺嘧啶。磺胺嘧啶作为靶分子,通过悬浮聚合制备了1～10μm的分子印迹聚合物。将分子印迹聚合物装入聚四氟乙烯管中,作为固相萃取柱,并联在八通阀上,用于在线选择吸附磺胺嘧啶。在最佳条件下,测得磺胺嘧啶线性范围7.0×10–9～9.0×10–7g/mL,方法的检出限为(3σ)2×10–10g/mL,11次平行测定3.0×10–8g/mL的磺胺嘧啶溶液的化学发光强度相对标准偏差为3.4%。方法能够用于检测肉类产品中残留的磺胺嘧啶。