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.     

水杨酸分子印迹电化学传感器的制备及其性能研究

以水杨酸作为模板分子,通过原位聚合法,在玻碳电极表面合成了水杨酸分子印迹聚合物膜,并用方波伏安法对该印迹电极进行了分析研究.当吸附时间为7 min时,印迹电极对水杨酸浓度响应的线性范围为1.0×10-5~2.6×10-5mol/L,检出限(S/N=3)为2.0×10-6mol/L,同一支印迹电极对水杨酸响应值的RSD为...     

A novel molecularly imprinted electrochemiluminescence sensor for isoniazid detection

Based on Ru(bpy)(3)(2+)-Au nanoparticles decorated multi-walled carbon nanotubes composites and a molecularly imprinted polymer (MIP), we propose a novel molecularly imprinted electrochemiluminescence (ECL) sensor to selectively determine isoniazid (INH). The MIP is synthesized through electrochemical copolymerization of acrylamide and N,N'-methylene diacrylamide in the presence of INH template molecules. The enhanced ECL intensity is linear in the range of 0.1 to 110 μg cm(-3) and the detection limit is 0.08 μg cm(-3) (3σ) INH with relative standard deviation 3.8% (n = 6) for 8 μg cm(-3). As a result, the sensor has been successfully applied to the determination of INH in human urine and pharmaceutical samples. Moreover, the possible ECL mechanism is discussed.     

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 and characterization of novel molecularly imprinted polymers based on thiourea receptors for nitrocompounds recognition

Molecularly imprinted polymers (MIPs) for the recognition of nitro derivatives are prepared from three different (thio)urea-bearing functional monomers. The binding capability of the polymers is characterized by a batch binding experiment. The imprinting factors and affinity constants (K) of the imprinted polymers exhibit the same tendency as the binding constants (K_a) of the functional monomers to the target substance in solution. Not only nitrofurantoin is efficiently bound by these MIPs but also a broad spectrum of other nitro compounds is bound with at the intermediate level, addressing that these (thio)urea-based monomers can be utilized to prepare a family of MIPs for various nitro compounds, which can be applied as recognition elements in separation and analytical application.     

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.     

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%。     

A resonance light scattering sensor based on bioinspired molecularly imprinted polymers for selective detection of papain at trace levels

A novel resonance light scattering sensor based on the molecularly imprinted polymers (MIPs) technique was developed for specific recognition of the trace quantities of papain (Pap). In this sensor, as the specific recognition element, an excellent biocompatibility of protein-imprinted polymer without fluorescent materials was easily prepared, which based on the effective synthesis of mussel-inspired bionic polydopamine (PDA) on the surface of SiO₂ nanoparticles (SiO₂@PDA NPs). This recognition element could capture the target protein selectively, which led to the enhancement of resonance light scattering intensity with the increasing of the target protein concentration. The sensor was applied to determine Pap in the linear concentration range of 2.0–20.0 nM with a correlation coefficient r = 0.9966, and a low detection limit of 0.63 nM. The relative standard deviation for 14 nM of Pap was 1.02% (n = 7). In addition, the specificity study confirmed the resultant Pap-imprinted SiO₂@PDA NPs had a high-selectivity to Pap, and the practical analytical performance was further examined by evaluating the detection of Pap in the dietary supplement with satisfactory results, with good recoveries of 97.5–105.3%.     

Fabrication of an electrochemical sensor based on computationally designed molecularly imprinted polymers for determination of cyanazine in food samples

A computational approach was used for screening functional monomers and polymerization solvent in the rational design of molecularly imprinted polymers (MIPs). It was based on the comparison of the binding energy of the complexes between the template and functional monomers. On the basis of computational results, acrylamide (AAM) and toluene were selected as functional monomer and polymerization solvent, respectively. The MIP, embedded in the carbon paste electrode, functioned as a selective recognition element and pre-concentrator agent for cyanazine determination by using cathodic stripping voltammetric method. The MIP-CP electrode showed very high recognition ability in comparison with NIP-CPE. Some parameters affecting the sensor response were optimized, and then the calibration curve was plotted. A dynamic linear range of 5.0–1000 nM was obtained. The detection limit of the sensor was calculated as 3.2 nM. This sensor was successfully used for cyanazine determination in food samples.     

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.     

聚苯胺分子印迹膜电化学传感器检测氯霉素

以苯胺为功能单体和交联剂,氯霉素(chloramphenicol,CAP)为模板分子,采用电化学聚合法(循环伏安法)在金电极上合成了对CAP具有快速响应能力的聚苯胺分子印迹膜;结合差示脉冲伏安法建立了针对氯霉素的检测方法,并将所制备的聚苯胺分子印迹膜用作电化学传感器以测定氯霉素眼药水中的氯霉素.结果表明,所制备的聚苯胺分子印迹膜具有制备简单、响应快速、灵敏度高、再生性能良好等特点;其对氯霉素眼药水中的氯霉素的检测结果令人满意,有望用于实际样品中氯霉素的检测.     

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.     

Voltammetric dopamine sensor based on three-dimensional electrosynthesized molecularly imprinted polymers and polypyrrole nanowires

Three-dimensional structures comprising polypyrrole nanowires (PPyNWs) and molecularly imprinted polymer (MIP) were prepared by electropolymerization on the surfaces of a glassy carbon electrode (GCE). The modified GCE possesses both large surface area and good electrocatalytic activity for oxidizing dopamine (DA), and this leads to high sensitivity. The electropolymerized MIP has a large number of accessible surface imprints, and this makes the GCE more selective. Under optimal conditions and at a working voltage of typically 0.23 V (vs. SCE), the calibration plot is linear in the 50 nM to 100 μM DA concentration range, and the limit of detection is 33 nM. The sensor has been successfully applied to the analysis of DA in injections.

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Graphical abstract Schematic of a three-dimensional nanocomposite based dopamine sensing platform based on the use of a molecularly imprinted polymer and poly(pyrrole) nanowires. The modified polypyrrole nanowires and molecularly imprinted polymer endowed high electrocatalytic capacity and good selectivity for dopamine recognition, respectively.

     

A capacitive sensor based on molecularly imprinted polymers and poly(p-aminobenzene sulfonic acid) film for detection of pazufloxacin mesilate

A novel capacitive sensor for pazufloxacin mesilate (pazufloxacin) determination was developed by electropolymerizing p-aminobenzene sulfonic (p-ABSA) and molecularly imprinted polymers (MIPs), which was synthesized through thermal radical copolymerization of metharylic acid (MAA) and ethyl-ene glycol dimethacrylate (EGDMA) in the presence of pazufloxacin template molecules, on the gold electrode surface. Furthermore, 1-dedecanethiol was used to insulate the modified electrode. Alter-nating current (ac) impedance experiments were carried out with a Model IM6e to obtain the capaci-tance responses. Under the optimum conditions, the sensor showed linear capacitance response to pazufloxacin in the range of 5 ng·mL-1 to 5 μg·mL-1 with a relative standard deviation (RSD) 5.3% (n=7) and a detection limit of 1.8 ng·mL-1. The recoveries for different concentration levels of pazufloxacin samples varied from 94.0% to 102.0%. Electrochemical experiments indicated the capacitive sensor exhibited good sensitivity and selectivity and showed excellent parameters of regeneration and stabil-ity.     

A novel high selectivity chemiluminescence sensor for fenvalerate based on double-sided hollow molecularly imprinted materials

Novel fenvalerate double-sided hollow molecularly imprinted microspheres (fenvalerate-DHMIMs) were fabricated by in situ polymerization with the help of mesoporous silica microspheres (MSMs) in this paper for the very first time. Scanning electron microscope was employed to characterize the surface morphology of the fenvalerate-DHMIMs. Taking advantage of the quenching effect of fenvalerate on the luminol-H(2)O(2)-NaOH chemiluminescence system, a new model was established to determine fenvalerate by a highly selective flow injection chemiluminescence method. The traditional flow-through cell was replaced by a novel Y-shaped column. The chemiluminescence intensity was linear with fenvalerate concentration over the range of 5.0 × 10(-8) to 2.0 × 10(-5) g mL(-1) and the detection limit was 2.2 × 10(-8) g mL(-1). The relative standard deviation (RSD) for the determination of 2.0 × 10(-6) g mL(-1) fenvalerate was 1.4% (n = 11). The proposed method was applied to the determination of fenvalerate in real samples with satisfactory results.     

Application of molecularly imprinted polymers for electrochemical detection of some important biomedical markers and pathogens

The determination of biomedical markers and pathogens using electrochemical sensors is a well-established technique in which the transducer and the recognition element are used to detect the target molecule. There is a growing interest in molecularly imprinted polymer (MIPs) applications as promising recognition elements. The use of MIPs as recognition elements in electrochemical sensors offers the advantages of being fast, low cost, and, at the same time, provides accurate and selective results compared with other commonly applied routine methods for biomedical markers and pathogen detection. Compared with other nanomaterials and aptamer-based biosensors, MIP-based sensors offered excellent selectivity for low-priced reagents to be used. The aim of the current review is to discuss the most recent applications of MIP-based electrochemical sensors (2019–2021) as promising detection devices for some important biomarkers, enzymes, and pathogens, such as viruses, bacteria, and toxins.     

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.     

Photopolymerization and photostructuring of molecularly imprinted polymers for sensor applications—A review

Biosensors are already well established in modern analytical chemistry, and have become important tools for clinical diagnostics, environmental analysis, production monitoring, drug detection or screening. They are based on the specific molecular recognition of a target molecule by a biological receptor such as an antibody or an enzyme. Synthetic biomimetic receptors like molecularly imprinted polymers (MIPs) have been shown to be a potential alternative to biomolecules as recognition element for biosensing. Produced by a templating process at the molecular level, MIPs are capable of recognizing and binding target molecules with similar specificity and selectivity to their natural analogues. One of the main challenges in MIP sensor development is the miniaturization of MIP structures and their interfacing with the transducer or with a microchip. Photostructuring appears thereby as one of the most suitable methods for patterning MIPs at the micro and nano scale, directly on the transducer surface. In the present review, a general overview on MIPs in biosensing applications is given, and the photopolymerization and photopatterning of MIPs are particularly described.     

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.     

A molecularly imprinted polymer based on functionalized multiwalled carbon nanotubes for the electrochemical detection of parathion-methyl

A novel composite of vinyl group functionalized multiwalled carbon nanotubes (MWCNTs) molecularly imprinted polymer (MIP) was synthesized and applied as a molecular recognition element to construct an electrochemical sensor for parathion-methyl in this paper. The special molecular recognition properties of parathion-methyl mainly dominated by π-π, p-π interaction and hydrogen bonding formed among functional monomer, template and matrix. A series of electrochemical experiment results proved that the prepared material had good adsorption capacity and fast mass transfer rate to parathion-methyl. The good selectivity of the sensor allowed fine discrimination between parathion and paraoxon, which had similar structures to parathion-methyl. The response of the MIPs was linearly proportional to the concentration of parathion-methyl over the range of 2.0 × 10(-7) to 1.0 × 10(-5) mol L(-1) with a lower detection limit of 6.7 × 10(-8) mol L(-1) (S/N = 3). This sensor was also applied in the detection of parathion-methyl in pear and cucumber with average recoveries of between 94.9% and 106.2% (RSD < 5%) being obtained. The results mentioned above show that the novel electrochemical sensor is an ideal device for the real-time determination of parathion-methyl in real samples.