Colorimetric molecularly imprinted polymer sensor array using dye displacement

A colorimetric sensor array composed of seven molecularly imprinted polymers was shown to accurately identify seven different aromatic amines. The response patterns were systematically classified using linear discriminant analysis with 94% classification accuracy. Analyses of the response patterns of the analytes to the imprinted polymer array suggest that the different selectivity patterns, although subtle, appear to arise from the imprinting process. The molecular imprinting process enabled the rapid preparation of the polymers in the array from ethylene glycol dimethacrylate and methacrylic acid (80:20) in the presence of six different template molecules plus a blank nonimprinted polymer. The response of the imprinted polymer array was coupled to a colorimetric response, using a dye displacement strategy. A benzofurazan dye was selected and shown to give an accurate measure of the binding properties of the imprinted polymer array to all seven analytes. The colorimetric response also enabled the inclusion of analytes that are not spectroscopically active and were not among the original analytes that were used as template molecules. This broadens the potential utility of the imprinted polymer sensor array strategy to a wider range of analytes and applications.     

Chromatographic characterisation, under highly aqueous conditions, of a molecularly imprinted polymer binding the herbicide 2,4-dichlorophenoxyacetic acid

The affinity of a 2,4-dichlorophenoxyacetic acid (2,4-D) molecularly imprinted polymer (MIP), which was synthesised directly in an aqueous organic solvent, for its template (2,4-D) was studied and compared with the affinity exhibited by two other reference (control) polymers, NIPA and NIPB, for the same analyte. Zonal chromatography was performed to establish the optimal selectivity, expressed as imprinting factor (IF), under chromatographic conditions more aqueous than those described so far in the literature. Frontal analysis (FA) was performed on columns packed with these polymers, using an optimized mobile phase composed of methanol/phosphate buffer (50/50, v/v), to extract adsorption isotherm data and retrieve binding parameters from the best isotherm model. Surprisingly, the template had comparable and strong affinity for both MIP (K = 3.8 × 10⁴ M⁻¹) and NIPA (K = 1.9 × 10⁴ M⁻¹), although there was a marked difference in the saturation capacities of selective and non-selective sites, as one would expect for an imprinted polymer. NIPB acts as a true control polymer in the sense that it has relatively low affinity for the template (K = 8.0 × 10² M⁻¹). This work provides the first frontal chromatographic characterization of such a polymer in a water-rich environment over a wide concentration range. The significance of this work stems from the fact that the chromatographic approach used is generic and can be applied readily to other analytes, but also because there is an increasing demand for well-characterised imprinted materials that function effectively in aqueous media and are thus well-suited for analytical science applications involving, for example, biofluids and environmental water samples.     

Molecularly imprinted polymer sensor arrays

An eight channel molecularly imprinted polymer sensor array was prepared that was able to differentiate six different aryl amine analytes, including diastereomers with 94% accuracy.     

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%.     

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.     

Potentiometric propranolol-selective sensor based on molecularly imprinted polymer

A novel potentiometric sensor based on molecularly imprinted polymer (MIP) for propranolol, an adrenergic-blocking drug, was designed. The influence of molecularly imprinted polymer particle content and sodium tetraphenylborate additives in polyvinylchloride membrane was shown. The electrodes show near-Nernstian responses down to 10^?4–10^?5?M propranolol concentration. The potentiometric response of MIP-based sensor for propranolol in mixed nonaqueous medium was shown at first. Sensor selectivity relative to various inorganic cations, atenolol and metoprolol, was reported. Direct potentiometry was used to determine propranolol in aqueous modeling solutions and pharmaceutical preparations with good results.     

Acetylsalicylic acid electrochemical sensor based on PATP-AuNPs modified molecularly imprinted polymer film

A novel electrochemical sensor based on molecularly imprinted polymer film has been developed for aspirin detection. The sensitive film was prepared by co-polymerization of p-aminothiophenol (p-ATP) and HAuCl(4) on the Au electrode surface. First, p-ATP was self-assembled on the Au electrode surface by the formation of Au-S bonds. Then, the acetylsalicylic acid (ASA) template was assembled onto the monolayer of p-ATP through the hydrogen-bonding interaction between amino group (p-ATP) and oxygen (ASA). Finally, a conductive hybrid membrane was fabricated at the surface of Au electrode by the co-polymerization in the mixing solution containing additional p-ATP, HAuCl(4) and ASA template. Meanwhile, the ASA was spontaneously imprinted into the poly-aminothiophenol gold nanoparticles (PATP-AuNPs) complex film. The amount of imprinted sites at the PATP-AuNPs film significantly increases due to the additional replenishment of ASA templates. With the significant increasing of imprinted sites and doped gold nanoparticles, the sensitivity of the molecular imprinted polymer (MIP) electrode gradually increased. The molecularly imprinted sensor was characterized by electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and cyclic voltammetry (CV). The linear relationships between current and logarithmic concentration were obtained in the range from 1 nmol L(-1) to 0.1 μmol L(-1) and 0.7 μmol L(-1) to 0.1 mmol L(-1). The detection limit of 0.3 nmol L(-1) was achieved. This molecularly imprinted sensor for the determination of ASA has high sensitivity, good selectivity and reproducibility, with the testing in some biological fluids also has good selectivity and recovery.     

Preconcentration of 2,4-dichlorophenoxyacetic acid on molecularly imprinted polymers and its subsequent determination by high performance liquid chromatography

The potency of molecularly imprinted polymers (MIP) for 2,4-dichlorophenoxyacetic acid (2,4-D) in the dynamic sorption preconcentration (solid phase extraction) of 2,4-D and three other structurally related species (2,4-dichlorophenol, 2-chlorophenol, and dikamba) from aqueous solutions is assessed. The optimal conditions for preconcentration are found: 0.01 M HCl, 25–100 mL of solution, flow rate of solution 0.7 mL/min, column (15 × 2.7 mL), and sorbent weight 0.04 g. The analytes are desorbed with 1 mL of methanol and detected in the eluate by reversed-phase HPLC with spectrophotometric detection at 225 nm. The detection limit for 2,4-D makes 0.4 μg/mL without preconcentration and 0.01 μg/mL with preconcentration from a volume of 100 mL. The procedure is applied to the analysis of model mixtures based on fresh river water.     

A visible light responsive molecularly imprinted photoelectrochemical sensor for the sensitive detection of BSA

Journal of Solid State Electrochemistry - A molecularly imprinted photoelectrochemical (PEC) cathodic sensor was developed for the detection of bovine serum albumin (BSA). The PEC sensor was...     

Selective recognition of ovalbumin using a molecularly imprinted polymer

Micro-contact imprinting has been used to form thin-film molecular imprints of ovalbumin (OVA) in polymers supported on glass slides. Thermocalorimetric data was used to optimise the choice of functional monomer and cross-linker to maximise selectivity and minimise non-specific recognition.A polymer comprising polyethyleneglycol 400 dimethacrylate (95 vol.%) and methacrylic acid (5 vol.%) showed both maximum recognition for OVA when made as a molecularly imprinted polymer (MIP), and minimal recognition when made as a non-imprinted, i.e. control polymer. OVA rebinding to the molecularly imprinted polymer, from a buffered 2 µM OVA solution, was 1.55 × 10^{− 11} mol cm^{− 2}, while the control polymer showed 10-fold less re-binding, i.e. 0.154 × 10^{− 11} mol cm^{− 2}.Experiments in which human serum albumin (HSA), conalbumin, ovomucoid or lysozyme, were re-bound to the polymers, either as single proteins or in competition with OVA, showed them to have low affinity for the polymer formulation used. Of the competing proteins examined, in non-competitive binding experiments, HSA showed the greatest affinity 0.45 × 10^{− 11} mol cm^{− 2} for the OVA imprinted polymer. In two protein competition experiments, i.e. with OVA and a competing protein present at equal concentrations (2 µM), OVA binding to the OVA imprinted polymer was in all cases significantly greater than that of the competitor.     

马尿酸分子印迹电化学传感器的制备及应用

采用超声法制备g-C3N4/NiO复合催化材料,将其滴涂在玻碳电极(GCE)表面构建g-C3N4/NiO/GCE催化电极。采用电聚合方法,以马尿酸为模板分子,邻苯二胺为功能单体构建M IP/g-C3N4/NiO/GCE传感器。采用时间-电流法对传感器制备条件优化。结果表明,复合催化材料对H2O2具有良好的催化效果。分子印迹传感器对马尿酸具有良好的选择性。在优化条件下,马尿酸质量浓度在0.05~2 mg/L范围内,电极电流响应与浓度呈良好的线性关系,检出限为7.1μg/L。将电极用于尿液中马尿酸的检测,回收率在87.3%~95.3%之间。     

葛根素分子印迹电化学传感器的制备及研究

以丙烯酰胺为功能单体,葛根素为模板分子,马来松香丙烯酸乙二醇酯为交联剂,采用循环伏安法合成了葛根素分子印迹膜,并以此为识别元件制备了葛根素电化学传感器。该传感器对葛根素具有高度的选择性和良好的敏感度,葛根素氧化峰电流与其浓度在6.0×10-8～1.6×10-3mol/L范围内呈良好的线性关系,检出限为2.0×10-8mol/L。将此传感器用于葛根素注射液和木瓜葛根片中葛根素的含量测定,回收率为97.7%～106.4%。     

Potentiometric sensor for determination of neutral bisphenol A using a molecularly imprinted polymer as a receptor

The aim of this paper is to develop a potentiometric sensing methodology for sensitive and selective determination of neutral phenols by using a molecularly imprinted polymer as a receptor. Bisphenol A (BPA), a significant environmental contaminant, is employed as the model target. The BPA-imprinted polymer is synthesized by the semi-covalent technique and incorporated into a plasticized poly(vinyl chloride) membrane doped with the tridodecylmethylammonium salt. The present electrode shows a linear anionic potential response over the concentration range from 0.1 to 1 μM with a detection limit of 0.02 μM, and exhibits an excellent selectivity over other phenols. The proposed approach has been successfully applied to the determination of BPA released from real plastic samples. It offers promising potential in development of potentiometric sensors for measuring neutral phenols at trace levels.     

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.     

A procedure for determining 2,4-dichlorophenoxyacetic acid using immobilized molecular imprinted polymers and an amperometric biosensor

A combined procedure was suggested for determining dichlorophenoxyacetic acid using polyacrylamide-based polymers immobilized in a nitrocellulose matrix with molecular imprints and amperometric cholinesterase biosensors. The sorbability of 2,4-dichlorophenoxyacetic acid on the immobilized polymers and reference polymers was evaluated, and the quantitative characteristics of the sorption-desorption process were calculated.     

Simple and effective 3D recognition of domoic acid using a molecularly imprinted polymer

We have developed a simple and effective molecular imprinting technique to target compounds with flexible structure. Domoic acid (DA), an amnesic shellfish poison, was used as the target compound while many acidic compounds (mono-, di-, and tricarboxylic acids) were used as template molecules for molecularly imprinted polymers (MIPs). Evaluation of selective recognition abilities using liquid chromatography revealed that the highest selective recognition ability for DA was found when pentane-1,3,5-tricarboxylic acid (1,3,5-PeTA) was used as the template. Computer modeling studies of the DA structure suggested that the observed selective recognition depended on the structural changes in DA at the recognition site of the MIPs as well as spatial distance between the COOH groups in DA and 1,3,5-PeTA. Using the 1,3,5-PeTA-MIP, we could easily purify DA from blue mussel extracts by solid-phase extraction.     

A piezoelectric biomimetic sensor for aminopyrine with a molecularly imprinted polymer coating

A molecularly imprinted polymer for aminopyrine was synthesized using methacrylic acid as functional monomer. The polymer was employed as the recognition element of a piezoelectric bulk acoustic wave biomimetic sensor for aminopyrine. Influencing factors were investigated in detail and optimized. This sensor exhibited high selectivity and sensitivity to aminopyrine. The response range of the sensor was between 5.0 x 10(-8) and 1.0 x 10(-4) M with a detection limit of 2.5 x 10(-8) M in the aqueous system. Scatchard analysis with UV spectrophotometry showed that the same class of binding sites was formed in the molecularly imprinted polymer in the studied concentration range, and the dissociation constant and the apparent maximum number of these binding sites were estimated to be 2.29 mM and 165.0 mumol g-1 dry polymer, respectively. Impedance analysis was employed to verify the imprinting effect and lack of variation in the viscoelasticity of the polymer coating during detection.     

Biomimetic piezoelectric quartz sensor for caffeine based on a molecularly imprinted polymer

A piezoelectric quartz sensor coated with molecularly imprinted polymer (MIP) for caffeine was developed. The MIP was prepared by co-polymerizing methacrylic acid (MAA) and ethylene glycol dimethacrylate (EDMA) in the presence of azobis(isobutyronitrile) as initiator, caffeine as template molecule, and chloroform as solvent. The MIP suspension in polyvinyl chloride/tetrahydrofuran (6:2:1 w/w/v) solution was spin coated onto the surface of the electrode of a 10 MHz AT-cut quartz crystal. The sensor exhibited a linear relationship between the frequency shift and caffeine concentration in the range of 1×10^–7 mg mL^–1 up to 1x10^–3 mg mL^–1 [correlation coefficient (r)=0.9935] in a stopped flow measurement mode. It has a sensitivity of about 24 Hz/ln(concentration, mg mL^–1). A steady-state response was achieved in less than 10 min. The performance characteristic of the sensor shows a promising and inexpensive alternative method of detecting caffeine. Surface studies were carried out for the reagent phase of the sensor using SEM, AFM, and XPS analysis in order to elucidate the imprinting of the caffeine molecule. The SEM micrograph, AFM image, and XPS spectra confirmed the removal of caffeine by Soxhlet extraction in the imprinting process and the rebinding of caffeine to the MIP sensing layer during measurement.     

Bulk acoustic wave sensor for herbicide assay based on molecularly imprinted polymer

A novel molecularly imprinted polymer (MIP) coated bulk acoustic wave (BAW) sensor was fabricated for liquid phases. It can be used as a sensitive portable implement for the assay of 2,4-dichlorophenoxyacetic acid. A logarithmic response relationship between 2.0 × 10^–7 M and 5.0 × 10^–4 M was found. The detection limit was 1.0 × 10^–7 M. Recoveries were 93.2–108.7%. Influencing factors were investigated in detail and optimized.