桑色素分子印迹传感器的制备与应用

以邻氨基酚( o-AP)为功能单体,桑色素为模板分子,基于分子间的相互作用力,在金电极表面电聚合制备具有特异性识别孔穴的桑色素分子印迹传感器膜。采用循环伏安法( CV)、差分脉冲伏安法( DPV)等研究了分子印迹膜的性能和分子印迹效应。探索了聚合膜配比及聚合扫描圈数对传感器性能的影响,优化了洗脱时间和印迹时间。比较了此传感器对其结构相似物的选择性响应,发现其对桑色素检测具有良好的选择性。在最佳实验条件下,此传感器对桑色素浓度定量测定范围为0.05~1.70μmol/L,线性方程为I(μA)=1.0800lgc(mol/L)+9.3599, R=0.9934,检出限为0.01μmol/L。用此传感器测定黑茶样品中桑色素的含量,加标回收率为104.0%~108.0%。     

Novel amperometric sensor using metolcarb-imprinted film as the recognition element on a gold electrode and its application

A molecularly imprinted film is electrochemically synthesized on a gold electrode using cyclic voltammetry to electropolymerize o-aminothiophenol in the presence of metolcarb (MTMC). The mechanism of the imprinting process and a number of factors affecting the activity of the imprinted film are discussed and optimized. Scanning electron microscope observations and binding measurements have proved that an MTMC-imprinted film (with a thickness of nearly 100 nm) was formed on the surface of the gold electrode. The film exhibited high binding affinity and selectivity towards the template MTMC, as well as good penetrability, reproducibility and stability. A novel amperometry sensor using the imprinted film as recognition element was developed for MTMC determination in food samples. Under the experimental conditions, the MTMC standard is linear within the concentration range studied (r² = 0.9906). The limit of detection (S/N = 3) of the modified electrode was achieved to 1.34 × 10⁻⁸ mol L⁻¹. Recoveries of MTMC from spiked apple juice, cabbage and cucumber samples for the developed electrochemical assay ranged from 94.80% to 102.43%, which was with great correlation coefficient (0.9929) with results from high-performance liquid chromatography. In practical application, the prepared amperometric sensor also showed good reproducibility and long lifetime for storage. The research in this study has offered a rapid, accurate and sensitive electrochemical method for quantitative determination of MTMC in food products.     

Molecularly imprinted polymer film interfaced with Surface Acoustic Wave technology as a sensing platform for label-free protein detection

Molecularly imprinted polymer (MIP)-based synthetic receptors integrated with Surface Acoustic Wave (SAW) sensing platform were applied for the first time for label-free protein detection. The ultrathin polymeric films with surface imprints of immunoglobulin G (IgG-MIP) were fabricated onto the multiplexed SAW chips using an electrosynthesis approach. The films were characterized by analyzing the binding kinetics recorded by SAW system. It was revealed that the capability of IgG-MIP to specifically recognize the target protein was greatly influenced by the polymer film thickness that could be easily optimized by the amount of the electrical charge consumed during the electrodeposition. The thickness-optimized IgG-MIPs demonstrated imprinting factors towards IgG in the range of 2.8–4, while their recognition efficiencies were about 4 and 10 times lower toward the interfering proteins, IgA and HSA, respectively. Additionally, IgG-MIP preserved its capability to recognize selectively the template after up to four regeneration cycles. The presented approach of the facile integration of the protein-MIP sensing layer with SAW technology allowed observing the real-time binding events of the target protein at relevant sensitivity levels and can be potentially suitable for cost effective fabrication of a biosensor for analysis of biological samples in multiplexed manner.     

Morphine Sensing by a Green Modified Molecularly Imprinted Poly L‐Lysine/Sodium Alginate‐activated Carbon/Glassy Carbon Electrode Based on Computational Design

A different molecularly imprinted composite film with the exploit of computational design is synthesized. The proposed composite is used for electrode modification to determine morphine. The ratio of monomer to template in optimum condition was obtained 4. The modification of the electrode was achieved by electropolymerizing L‐lysine in the presence of morphine on the surface of sodium alginate and activated carbon (SA‐AC) on glassy carbon electrode (GCE). The SA‐AC composite with special surface area suits for making sensitive sensors. Morphine showed an anodic peak in buffer solution of phosphate (pH=6.0) on MIP/SA‐AC/GCE. The optimization of the practical factors on the response and electrochemical behavior of template morphine on the modified electrode were precisely surveyed. The DPV outcomes exhibit high sensitivity for morphine detection within 0.1–1000.0 μM and limit of detection as 48 nM (S/N=3). The application of this disposable sensor in the case of urine samples was quite satisfactory.     

Highly Sensitive Molecularly Imprinted Sensor Based on Platinum Thin‐film Microelectrode for Detection of Chloramphenicol in Food Samples

A highly sensitive and selective electrochemical biomimetic sensor was fabricated for fast detection of chloramphenicol (CAP) in honey and milk samples. Platinum thin‐film microelectrode (Pt TFME), which could provide unique electrochemical properties and achieve measurement using very limited solution volumes, was surface‐modified by electropolymerizing o‐phenylenediamine. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the preparation process of CAP‐imprinted poly(o‐phenylenediamine) film and rebinding ability of CAP into the imprinted cavities. The electrochemical properties of the sensor were further investigated with square wave voltammetry (SWV) by using K₃Fe(CN)₆ as an electroactive probe. The current difference of oxidation peaks of K₃Fe(CN)₆ had a good linear relationship with the concentration of CAP in the range of 0.9–10 nM. The detection limit was 0.39 nM based on the signal to noise ratio of 3. The developed sensor was successfully applied to determine CAP in honey and milk samples, and the result was in good agreement with that obtained by high performance liquid chromatography‐mass spectrometry (HPLC‐MS). The sensor showed high sensitivity and excellent selectivity to CAP in comparison to other structurally related and/or normally existing antibiotics, and demonstrated great promise for the rapid quantification of CAP in real food samples and field analysis.     

On-line molecularly imprinted solid-phase extraction for the selective spectrophotometric determination of nicotine in the urine of smokers

This work describes an on-line molecularly imprinted solid-phase extraction (MISPE) method for spectrophotometric determination of nicotine in urine samples of smokers. This method is based on manganese (VII) to manganese (VI) reduction in an alkaline medium, promoted by nicotine. Two wash solutions (1:4 (v/v) acetonitrile:sodium hydroxide - pH 11.4, and nitric acid - pH 2.5) were employed to circumvent interferences. Aqueous solutions containing nicotine plus different possible concomitants (cotinine, anabasine, norcotinine and caffeine) were tested individually. The analytical calibration curve was prepared in urine samples collected from non-smokers and spiked with nicotine standard from 1.1 to 60 μmol L⁻¹ (r² > 0.998). The limit of quantification and the analytical frequency were 1.1 μmol L⁻¹ and 11 h⁻¹, respectively. The precision, evaluated using 3, 10 and 30 μmol L⁻¹ nicotine in urine, was 10, 10 and 4% (intra-day precision) and 12, 13 and 5% (inter-day precision), respectively. Accuracy was checked through high performance liquid chromatography and the results did not present significant differences at the 95% confidence level according to the Student's t-test.     

三氯生分子印迹传感器的制备及其性能研究

应用分子印迹技术, 以邻苯二胺为功能单体、三氯生为模板, 用循环伏安法在玻碳电极表面合成了性能稳定的三氯生分子印迹聚合膜, 并用方波伏安法对此印迹传感器进行了分析应用研究.     

Amperometric morphine sensing using a molecularly imprinted polymer-modified electrode

This study incorporates morphine into a molecularly imprinted polymer (MIP) for the amperometric detection of morphine. The polymer, poly(3,4-ethylenedioxythiophene), PEDOT, is an electroactive film that catalyzes morphine oxidation and lowers the oxidization potential on an indium tin oxide (ITO) electrode. The MIP-PEDOT modified electrode is prepared by electropolymerizing PEDOT onto an ITO electrode in a 0.1 M LiClO₄ solution with template addition (morphine). After template molecule extraction, the oxidizing current of the MIP-PEDOT modified electrode is measured in a 0.1 M KCl solution (pH = 5.3) at 0.75 V (versus Ag/AgCl/sat’d KCl) with the morphine concentration varying in the 0.1-5 mM range. A linear range, displaying the relationship between steady-state currents and morphine concentrations, from 0.1 to 1 mM, is obtained. The proposed amperometric sensor could be used for morphine detection with a sensitivity of 91.86 μA/cm² per mM. A detection limit of 0.2 mM at a signal-to-noise ratio of 3 is achieved. Moreover, the proposed method can discriminate between morphine and its analogs, such as codeine.     

配位印迹聚合物在分析化学中的应用进展

分子印迹聚合物(MIP)是一种对目标分子(模板分子)具有选择性结合能力的聚合物.配位印迹聚合物(CIP)是基于金属离子与功能单体、模板分子间配位作用的分子印迹聚合物,既沿袭了MIP的优点,又具有适用于极性环境等优点,在食品、环境、生物、医药等领域目标物的识别中有良好的应用潜力.本文介绍了CIP的原理和特点,综述了CIP在分析化学中的应用进展,展望了CIP的发展前景.     

An optical reflected device using a molecularly imprinted polymer film sensor

A novel and highly selective optical sensor with molecularly imprinted polymer (MIP) film was fabricated and investigated. The optical sensor head employing a medium finesse molecularly imprinted polymer film has been fabricated and characterised. A blank polymer and formaldehyde imprinted polymer were using methacrylic acid as the functional monomer and the ethylene glycol dimethacrylate as a crosslinker. The transduction mechanism is discussed based on the changes of optical intensity of molecularly imprinted polymer film acting as an optical reflected sensor. Template molecules, which diffused into MIP, could cause film density, and refractive index change, and then induce measurable optical reflective intensity shifts. Based on the reflective intensity shifts, an optical reflection detection of formaldehyde was achieved by illuminating MIP with a laser beam. For the same MIP, the reflective intensity shift was proportional to the amount of template molecule. This optical sensor, based on an artificial recognition system, demonstrates long-time stability and resistance to harsh chemical environments. As the research moves forward gradually, we establish the possibilities of quantitative analysis primly, setting the groundwork to the synthesis of the molecular imprinted optical fiber sensor. The techniques show good reproducibility and sensitivity and will be of significant interest to the MIPcommunity.     

A novel method to prepare SPR sensor chips based on photografting molecularly imprinted polymer

A novel method to prepare surface plasmon resonance(SPR) sensor chips based on grafted imprinted polymer is explored. Benzophenone photografting system is used to grow molecularly imprinted polymer(MIP) films from the modified surface of gold substrate.The surface morphology and thickness of MIP films were investigated by scanning electronic microscope(SEM).The adsorption properties of sensor chip were studied by SPR spectroscopy.The results demonstrate that nano-MIP films can be constructed on the surface of gold substrate with the good adsorption of template molecules.     

Application of multivariate analysis to the screening of molecularly imprinted polymers for bisphenol A

A key issue in the synthesis of molecularly imprinted polymers (MIPs) is the identification and optimisation of the main factors that affect the material structure and its molecular recognition properties. This paper describes the application of an experimental design and multivariate analysis method for the synthesis of bisphenol A (BPA)-selective MIPs. Six factors with a large impact on the MIP synthesis and its analytical performance have been optimised: the amount of template, the type and the percentage of functional and cross-linking monomers, the polymerisation method (i.e. thermal or UV initiation) and the porogenic solvent. The polymers have been prepared in small-scale (mini-MIPs) and, after careful removal of the template, their BPA rebinding capacity has been evaluated and related to the MIP composition. Among the two functional monomers tested, namely 4-vinylpyridine (4-vpy) and methacrylic acid (MAA), the former rendered the best selectivity for BPA analysis. The partial least squares (PLS) models revealed that the photoinitiated polymers with a 1:1 ratio of 4-vinylpyridine to cross-linker (EDMA or TRIM) yield the highest specific binding. Such procedure is time and cost effective and can be used as a general tool in the preparation of MIPs for different analytes.     

Evaluation of a novel microextraction technique for aqueous samples: porous membrane envelope filled with multiwalled carbon nanotubes coated with molecularly imprinted polymer

A novel microextraction technique based on membrane-protected multiwalled carbon nanotubes coated with molecularly imprinted polymer (MWCNTs-MIP) was developed. In this technique, MWCNTs-MIP were packed inside a polypropylene membrane envelope, which was then clamped onto a paper clip. For extraction, the packed membrane envelope was first impregnated with toluene and then placed in sample solutions. Target analytes in the solutions were first extracted into toluene in the membrane envelope, and were then extracted specifically onto the MWCNTs-MIP. After the extraction, target analytes were desorbed in methanol for liquid chromatography analysis. MWCNTs-MIP of prometryn were used as a model to demonstrate the feasibility of this novel microextraction technique. Factors affecting the extraction including organic solvent, stirring rate, extraction time, salt concentration, and pH were investigated. Under the optimized conditions, the limits of detection (a signal-to-noise ratio of 3) for the selected triazine herbicides were 0.08-0.38 μg/L. The prepared membrane envelope could be used at least 50 times. The developed method was used for the analysis of the triazines spiked in river water, wastewater, and liquid milk, with recoveries ranging from 79.3-97.4, 58.9-110.3 and 76.2-104.9%, respectively.     

分子印迹聚合物在复杂体系分离中的应用研究进展

分子印迹聚合物的高选择性使其在复杂体系样品的净化富集中具有很强的应用潜力通过文献综述了分子印迹聚合物在固相提取中的应用．介绍了目前各种印迹聚合物制备方法,提出了在样品净化富集中选择淋洗条件需要考虑的问题及分子印迹聚合物在复杂体系分离中应用的发展前景。     

Development of a real-time capacitive biosensor for cyclic cyanotoxic peptides based on Adda-specific antibodies

The harmful effects of cyanotoxins in surface waters have led to increasing demands for accurate early warning methods. This study proposes a capacitive immunosensor for broad-spectrum detection of the group of toxic cyclic peptides called microcystins (∼80 congeners) at very low concentration levels. The novel analytical platform offers significant advances compared to the existing methods. Monoclonal antibodies (mAbs, clone AD4G2) that recognize a common element of microcystins were used to construct the biosensing layer. Initially, a stable insulating anchor layer for the mAbs was made by electropolymerization of tyramine onto a gold electrode surface, with subsequent incorporation of gold nanoparticles (AuNPs) on the glutaraldehyde (5%) activated polytyramine surface. The biosensor responded linearly to microcystin concentrations from 1 × 10⁻¹³ M to 1 × 10⁻¹⁰ M MC-LR standard with a limit of detection of 2.1 × 10⁻¹⁴ M. The stability of the biosensor was evaluated by repeated measurements of the antigen and by determining the capacitance change relative to the original response, which decreased below 90% after the 30th cycle.     

己烯雌酚印迹分子聚合物合成及其在残留分析中的应用

以己烯雌酚（Diethylstilbestrol,DES）为模板分子,α-甲基丙烯酸为功能单体,二甲基丙烯酸乙二醇酯为交联剂,合成己烯雌酚分子印迹聚合物;以该聚合物为填料制成固相萃取小柱,应用于己烯雌酚残留分析的样品前处理,并比较了该固相萃取小柱与C18固相萃取小柱对DES保留行为的差异。通过选择不同浓度的甲醇水溶液,己烯雌酚达到理想的分离纯化效果;对加标鸡肉样进行了含量测定,回收率可达95％以上。     

A novel molecularly imprinted polymer thin film as biosensor for uric acid

A novel amine-imide type conducting polymer, denoted as poly(PD-BCD), was molecularly imprinted on an indium-tin oxide (ITO) glass, with uric acid (UA) as the template and without any functional monomer. Intending to improve the imprinting efficiency, the polymer content was varied from 0.3 to 0.9 wt% during the preparation of the molecularly imprinted polymer (MIP), thereby varying the thickness of the polymer film; the content of UA as the template was maintained to be the same for all the films. The sensitivities of the thus prepared MIP electrodes were calculated to be more than 3-fold, compared to those of the corresponding non-MIP (NMIP) electrodes, which were obtained through the same method, however, without adding UA during their preparation. A polymer content of 0.6 wt% rendered the best performing MIP electrode, as judged by the imprinting efficiency and sensitivity of the electrode for UA. A linear relationship between steady-state currents and UA concentrations from 0 to 1.125 mM was obtained for both types of the sensors. The sensitivities of the MIP and the NMIP electrodes made with 0.6 wt% of polymer were calculated to be 24.72 and 6.63 μA mM⁻¹ cm⁻², respectively. The limit of detection (LOD) for this MIP was found to be 0.3 μM at a signal to noise ratio (S/N) of 3. This MIP electrode was used as a biosensor for the detection of UA in the presence of ascorbic acid (AA) in a sample containing these species in the same concentrations as those in a human serum. The selectivity of MIP electrode is higher than that of NMIP electrode, and the values are 28.76 and 8.85, respectively. The results are substantiated by using cyclic voltammetry (CV), linear sweep voltammetry, amperometry, and scanning electron microscopy.     

Development of a molecularly imprinted polymer for pyridoxine using an ion-pair as template

One of the main challenges in the molecularly imprinted polymers (MIP) field is the proper MIP design for water-soluble compounds because of appearance of serious drawbacks in polar solvents and insolubility of those compounds in non-polar solvents which are commonly used for MIP synthesis. In this work a novel and simple method for synthesis of molecularly imprinted polymers for a water-soluble compound was introduced. Pyridoxine was chosen as a target molecule and the ion-pair complex formed between pyridoxine ion (Py⁺) and dodecyl sulfate ion (DS⁻) was transferred into the chloroform via liquid-liquid extraction. Then polymerization was carried out in chloroform. The molecular mechanics and density functional theory were proposed to screen proper monomer. Binding energy, ΔE, of a template and a monomer as a measure of their interaction was considered. Ion-pair [Py⁺-DS⁻] was supposed as a template molecule and acrylic acid, methacrylic acid, allyamine, vinylpridine and 2-hydroxy ethyl methacrylate were as tested monomers. The MIP synthesized using acrylic acid showed the highest selectivity to pyridoxine as predicted from the ΔE calculation. The obtained MIP showed very high affinity against vitamin B6 in comparison to non-imprinted polymers (NIP). It was proved that the obtained MIP with introduced method was much better than that prepared in methanol as porogen. It was showed that the MIP prepared by this new method could be used as an adsorber for extraction and determination of pyridoxine in real and synthetic samples.     

Derivatization of 2-chlorophenol with 4-amino-anti-pyrine: a novel method for improving the selectivity of molecularly imprinted solid phase extraction of 2-chlorophenol from water

Molecularly imprinted polymer (MIP) may not selectively recognize small template of limited number of functional groups, such as 2-chlorophenol (2-CP). In this work, a novel method was proposed to improve the recognition ability of the molecularly imprinted solid phase extraction (MISPE) of 2-CP from environmental waters. This was achieved by derivatization of 2-CP with 4-amino-anti-pyrine (4-AAP) to enlarge its molecular size and add more binding sites. For that purpose, two MISPE methods of 2-CP were developed. In method 1, a polymer imprinted with 2-CP was used as the extracting sorbent but it suffered from low selectivity and high detection limit of 2-CP (7.10 ng L⁻¹). In method 2, a polymer imprinted with 4-AAP derivatized 2-CP (2-CP-4-AAP) was used as the extracting sorbent. Prior to loading the water sample it was subjected to a simple derivatization procedure with 4-AAP. Method 2 showed high recognition ability/selectivity towards 2-CP-4-AAP with lower detection limit of 0.05 ng L⁻¹ for 2-CP-4-AAP. Method 2 was able to detect the presence of 2-CP-4-AAP in unspiked real water samples and almost full spike recovery was achieved.     

Biomimetic properties and surface studies of a piezoelectric caffeine sensor based on electrosynthesized polypyrrole

An approach for preparing a chemical sensor for caffeine through the combination of molecularly imprinted polypyrrole and a piezoelectric quartz transducer was proposed. The caffeine-imprinted polymer was synthesized using galvanostatic electropolymerization of pyrrole monomer directly onto one of the gold electrodes of a 9 MHz AT-cut quartz crystal in the presence of caffeine. The optimum conditions for the electrosynthesis of the reagent phase were established. Caffeine molecules were entrapped in the matrix of polymer film, and were removed by subsequent washing with water, leaving behind pores capable of recognizing the target analyte molecule.The caffeine sensor was fixed in a measuring cell and measurement of the resonant frequency of the quartz crystal as it comes in contact with the caffeine solution was carried out in a stopped flow mode. A steady-state response was achieved in about 10 min. The sensor exhibited a linear relationship between the frequency shift and the ln of caffeine concentration in the range of 0.1-10 mg/mL (correlation coefficient, r = 0.9882). The sensitivity of the sensor was about 255 Hz/ln concentration (mg/mL). A good repeatability, R.S.D. = 9 (n = 6) for 0.5 mg/mL caffeine solution was also observed. The use of the sensor can present a potential low-cost option for determining caffeine.Surface analytical techniques such as scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were performed on the polymer coating in order to elucidate the imprinting process and rebinding of caffeine to the polymer matrix during the sensing process. The SEM micrographs and XPS spectra revealed features and structures that could support the imprinting and recognition of caffeine molecule by the imprinted polymer.