Imprinted Polymer Film Research Articles

Surface Molecularly Imprinted Polymer Film with Poly(p-aminothiophenol) Outer Layer Coated on Gold Nanoparticles Inner Layer for Highly Sensitive and Selective Sensing Paraoxon.

This paper presents the fabrication of a molecularly imprinted, polymer-based disposable electrochemical sensor for paraoxon (PO) determination. The sensor was based on a screen-printed carbon electrode (SPCE) modified with a surface molecularly imprinted poly (p-aminothiophenol) (PATP)/gold nanoparticles (AuNPs) composite film, which consisted of a PATP outer layer and an AuNPs inner layer. We report a novel strategy, combining surface molecularly imprinting and self-assembly directed electro-polymerization with high densely imprinting PO molecules in the PATP/AuNPs film. Firstly, AuNPs were in situ electrodeposited at the electrode surface, and then assembled with electropolmerizable functional monomer p-aminothiophenol (ATP). Subsequently, PO molecules were assembled onto the ATP monolayer-modified AuNPs, forming a basis of surface molecular imprinting. After that, replenished PO molecules were embedded in the PATP/AuNPs film by PO and the ATP molecular self-assembly directed electro-polymerization in the polymerization precursor mixture. The resulting imprinted PATP/AuNPs/SPCE possesses high sensitivity, affinity, and selectivity toward PO, with a low detection limit of 1 × 10−9 M. The proposed sensor was successfully applied for the determination of PO in fruit and vegetables, giving satisfactory recoveries. The strategy reported herein can be further expected to fabricate various molecular imprinted sensors for the determination of other pesticide residuals.

Ultrasensitive Determination of Human Chorionic Gonadotropin using a Molecularly Imprinted Electrochemical Sensor

AbstractIn this work, an ultrasensitive human chorionic gonadotropin (hCG) imprinted electrochemical sensor was constructed on the surface of a glassy carbon electrode (GCE) through surface imprinting. The imprinting template hCG was covalently bound onto the electrode which was modified by layer‐by‐layer coating of multi‐walled carbon nanotubes (MWCNTs), chitosan (CS) and glutaraldehyde (GA), Followed by electropolymerizing dopamine and effectively eluting, hCG imprinted polymer film was formed on the surface of the modified GCE. Benefiting from the application of MWCNTs and the imprinting effect, the designed sensor presented high sensitivity and selectivity with a widely linear detection range varying from 0.5 pg mL−1 to 250 ng mL−1 and a low detection limit of 0.035 pg mL−1 (S/N=3) which is superior to other electrochemical detection methods for hCG. Moreover, the imprinted sensor possessed low cross‐reactivity with multiple comparative proteins and high resistance to human serum effect. The results compared with enzyme‐linked immunosorbent assay (ELISA) further confirmed the accuracy and reliability of the hCG imprinted sensor. All electrochemical detection were performed in potassium hexacyanoferrate III (K3[Fe(CN)6]) and potassium hexacyanoferrate II (K4[Fe(CN)6]) trihydrate solution acting as a redox probe.

Molecular imprinting coupled with electrochemical analysis for plasma samples classification in acute myocardial infarction diagnostic

Electroanalysis of myoglobin (Mb) in 10 plasma samples of healthy donors (HDs) and 14 plasma samples of patients with acute myocardial infarction (AMI) was carried out with screen-printed electrodes modified first with multi-walled carbon nanotubes (MWCNT) and then with a molecularly imprinted polymer film (MIP), viz., myoglobin-imprinted electropolymerized poly(o-phenylenediamine). The differential pulse voltammetry (DPV) parameters, such as a maximum amplitude of reduction peak current (A, nA), a reduction peak area (S, nA × V), and a peak potential (P, V), were measured for the MWCNT/MIP-sensors after their incubation with non-diluted plasma. The relevance of the multi-parameter electrochemical data for accurate discrimination between HDs and patients with AMI was assessed on the basis of electrochemical threshold values (this requires the reference standard method (RAMP® immunoassay)) or alternatively on the basis of the computational cluster assay (this does not require any reference standard method). The multi-parameter electrochemical analysis of biosamples combined with computational cluster assay was found to provide better accuracy in classification of plasma samples to the groups of HDs or AMI patients.

Electrochemical determination of thrombin with molecularly imprinted polymers and multiwalled carbon nanotubes

The preparation and application of reagentless electrochemical thrombin molecularly imprinted sensors were studied using multiwalled carbon nanotubes as sensitivity-enhanced materials. The molecularly imprinted polymer film was prepared by the electropolymerization of o-phenylenediamine with thrombin as the template molecule onto the surface of multiwalled carbon nanotubes modified glassy carbon electrode. After removing thrombin, the poly-o-phenylenediamine molecularly imprinted film was obtained with specific recognition for thrombin. Using the poly-o-phenylenediamine molecularly imprinted polymers as the electron probe, the electrochemical molecularly imprinted sensor was fabricated for the detection of the protein thrombin. Under optimized experimental conditions, the sensor exhibited a good linear response from 10.0 fg/mL to 1.0 μg/mL for thrombin, with correlation coefficient 0.999 and a low detection limit of 1.7 fg/mL. The fabricated molecularly imprinted sensor can be applied to the detection of thrombin in actual sample bovine serum with satisfactory results.

Biomimetic ELISA detection of malachite green based on molecularly imprinted polymer film.

A highly selective and sensitive enzyme-linked immunosorbent assay (ELISA) was developed for the detection of malachite green (MG) using a molecularly imprinted polymer (MIP) film as bionic antibody. The MIP film, based on the self-polymerization of dopamine, was fabricated on the surfaces of a 96-well microplate. It showed specific recognition for MG in aqueous solution. A direct competitive ELISA method was established with the sensitivity reaching 10.31μgL-1 and the detection limit being 0.3μgL-1. The cross-reactivity of two structural analogues to MG was less than 10%. The average recovery tested by MG standard spiking was 88.8% for bass and 90.4% for water, and the relative standard deviations were less than 3.6%. All the above results indicated that the developed method could be used to detect MG in fish and water samples rapidly, specifically and accurately.

Development of highly electrocatalytic and electroconducting imprinted film using Ni nanomer for ultra-trace detection of thiamine

The present work describes a new molecularly imprinted polymer-based electrochemical sensor for thiamine (vitamin B1), which has been fabricated exploiting both surface imprinting and nanotechnology. Of two monomers used in this work, N-methacryloylglutamic acid served as a biocompatible and bio-adhesive material, whereas the assistant monomer, acryloylated nickel nanoparticles-functionalized multiwalled carbon nanotubes (Ni nanomer) induced large electro-catalytic and conducting activities to the molecularly imprinted polymer film. The polymer synthesis was carried out, following the ‘surface grafting from’ protocol, with the free radical polymerization directly on the surface of Ni nanomer modified pencil graphite electrode. The presence of functionalized-MWCNTs in the polymer film was inevitable to render stability to the coating via aromatic π−π interactions at the film-nanomer modified electrode interface. Thiamine, being electrochemically inactive, was estimated indirectly by a probe, hexamine ruthenium (II) chloride, with signal transduction via differential pulse anodic stripping voltammetric technique. The limits of detection were in the range 0.17–0.2ngmL−1 (S/N=3) in aqueous, multi-vitamin tablet, urine, and human blood serum, without any cross-reactivity and false- positives. The proposed sensor assures a reliable estimation of thiamine in the patients suffering from its acute deficiency.

A melamine based molecularly imprinted sensor for the determination of 8-hydroxydeoxyguanosine in human urine

A sensitive and facile molecular imprinted sensor has been fabricated using edge plane pyrolytic graphite (EPPG) for the determination of an important oxidative DNA damage product, 8-hydroxydeoxyguanosine (8-OHdG). The molecularly imprinted polymer film was fabricated by electropolymerization of melamine in the presence of 8-OHdG, on glutaraldehyde/poly 1,5-diaminonaphthalene modified EPPG. The imprinted sensor surface was characterized by using Field Emission Scanning Electron Microscopy, Electron Impedance Spectroscopy, Cyclic Voltammetry, Square Wave Voltammetry and UV–visible spectroscopy. The calibration response was linear over a concentration range of 20×10−9–3×10−6M of 8-OHdG with sensitivity and limit of detection (3σ/b) as 10.59µM/µA and 3×10−9M respectively. The common metabolites in urine, like uric acid, ascorbic acid, xanthine, hypoxanthine do not interfere up to 100-fold concentration. The imprinted sensor is also successfully employed for the determination of 8-OHdG in human urine sample of a renal failure patient.

Surface enhancement of a molecularly imprinted polymer film using sacrificial silica beads for increasing l-arabitol chemosensor sensitivity and detectability.

Molecular imprinting in polymers leads, among others, to synthetic receptors of high selectivity, comparable to that of their biological counterparts. Deposition of a thin non-porous molecularly imprinted polymer (MIP) film directly on a transducer surface enables fabrication of chemosensors for various health relevant biocompounds. However, the sensitivity of a chemosensor with such an MIP film as the recognition unit is limited, mostly because of slow analyte diffusion through this film. Herein, a simple procedure was developed to enhance, in a controlled way, the active surface area of an l-arabitol imprinted polymer film. For this, a macroporous MIP-(l-arabitol) film was synthesized and simultaneously deposited on a gold electrode of a quartz crystal resonator transducer by potentiodynamic electropolymerization. This large surface area film effectively enhanced analytical signals of mass changes at a quartz crystal microbalance. Hence, the l-arabitol limit of quantification was ∼16-fold better than that of the corresponding non-porous MIP film of the same mass.

Cationic pTyr/pSer imprinted polymers based on a bis-imidazolium host monomer: phosphopeptide recognition in aqueous buffers demonstrated by μ-liquid chromatography and monolithic columns.

We report on the design and characterization of imprinted cationic host polymers for selective trapping of phosphoserine and phosphotyrosine peptides. A series of imidazolium host monomers were synthesized and characterized with respect to binding affinity and stoichiometry of interaction with salts of phenylphosphonic acid. The strongest binders were subsequently used for the preparation of imprinted polymers in the form of crushed monoliths, using Fmoc-phosphotyrosine-ethyl ester or Fmoc-phosphoserine-ethyl ester as templates in combination with a hydrophilic crosslinking monomer. The polymers were compared with respect to binding and its dependence on solvent, and whether charged or uncharged host monomers were used. The recipes were subsequently implemented in the capillary monolith format for evaluation by micro-liquid chromatography in both buffered and organic media. Results from both tested formats reveal that the cationic host polymers displayed enhanced recognition in polar and buffered media, in contrast to neutral urea-based hosts which showed best results in acetonitrile rich mobile phases.

MIPs-graphene nanoplatelets-MWCNTs modified glassy carbon electrode for the determination of cardiac troponin I

An electrochemical sensor with high selectivity in addition to sensitivity was developed for the determination of cardiac troponin I (cTnI), based on the modification of cTnI imprinted polymer film on a glassy carbon electrode (GCE). The sensor was fabricated by layer-by-layer assembled graphene nanoplatelets (GS), multiwalled carbon nanotubes (MWCNTs), chitosan (CS), glutaraldehyde (GA) composites, which can increase the electronic transfer rate and the active surface area to capture a larger number of antigenic proteins. MWCNTs/GS based imprinted polymers (MIPs/MWCNTs/GS) were synthesized by means of methacrylic acid (MAA) as the monomer, ethylene glycol dimethacrylate (EGDMA) as the cross linker α,α′-azobisisobutyronitrile (AIBN) as the initiator and cTnI as the template. In comparison with conventional methods, the proposed electrochemical sensor is highly sensitive for cTnI, providing a better linear response range from 0.005 to 60 ng cm−3 and a lower limit of detection (LOD) of 0.0008 ng cm−3 under optimal experimental conditions. In addition, the electrochemical sensor exhibited good specificity, acceptable reproducibility and stability. Moreover, satisfactory results were obtained in real human serum samples, indicating that the developed method has the potential to find application in clinical detection of cTnI as an alternative approach.

A Reusable Electrochemical Biosensor for Monitoring of Small Molecules (Cortisol) Using Molecularly Imprinted Polymers

This paper establishes the feasibility of a reusable biosensor that can be operated and stored at room temperature, for detection of small molecules in low resource settings. The sensor was fabricated using molecularly imprinted polymers (MIP) and cortisol was chosen as a model analyte. Cortisol imprinted polymer films were prepared by electropolymerizing pyrrole on an electrode surface in the presence of cortisol. Electrochemical over-oxidation of polypyrrole (PPy) was performed for the controlled release of cortisol templates and to create cortisol specific imprinting sites. Stepwise fabrication of imprinted sensors was characterized through cyclic voltammetry (CV) and scanning electron microscopy (SEM). The sensor exhibited a detection limit of 1 pM L−1 for cortisol. A unique feature of the sensor was that cross-reactivity with prednisolone (which has 100% interference in ELISA), was minimized to 18.3% compared to ELISA. The sensitivity of the sensor remained over 90% after 7 cycles of elution/rebinding, while the sensitivity decreased by 10% after 4 weeks of storage at room temperature, suggesting the sensor can be used multiple times and used with low overhead costs in low resource settings such as agricultural fields. The sensor was used for detection of cortisol in saliva samples of farm workers; benchmarking with ELISA showed excellent correlation. These findings indicate that such a sensor can be used for in-field measurements of small molecules (e.g. cortisol).

Detection of Dopamine by a Biomimetic Electrochemical Sensor Based on Polythioaniline-Bridged Gold Nanoparticles.

A new biomimetic electrochemical sensor was developed for the detection of dopamine based on a glassy carbon electrode modified with electrochemically generated gold nanoparticles. The preparation of the polymer is simple and cost-effective, achieving the polymerization of thioaniline and generation of gold nanoparticles in a single step by cyclic voltammetry, in the presence of the target molecule, dopamine. After extraction, the imprinted polymer exhibits high sensitivity and selectivity for dopamine. Moreover, the developed imprinted polymer film allows the fast, direct detection of dopamine without the need of a redox mediator. The formation of a self-assembled monolayer of the monomer prior to electropolymerization ensures the adherence of the film onto the electrode surface, conferring good stability to the sensor (over two weeks). Cyclic voltammetry, electrochemical impedance spectroscopy, atomic force microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy were used for the complete characterization of the developed sensor, and differential pulse voltammetry was used for its testing.

Preparation of Molecularly Imprinted Electrochemical Sensor for Detection of Vincristine Based on Reduced Graphene Oxide/Gold Nanoparticle Composite Film

AbstractAn innovative molecularly imprinted electrochemical sensor was fabricated based on reduced graphene oxide (RGO) and gold nanocomposite (Au) for rapid detection of vincristine (VCR). The RGO‐Au composite membrane was obtained via direct one‐step electrodeposition technique of graphene oxide (GO) and chloroauric acid (HAuCl4) on the surface of a glassy carbon electrode (GCE) by means of cyclic voltammetry (CV) in the potential range between −1.5 and 0.6 V in phosphate buffer solution (PBS) of pH 9.18, which is capable of effectively utilizing its superior electrical conductivity, larger specific surface area due to its synergistic effect between RGO and Au. The molecularly imprinted polymers (MIPs) were synthesized on the RGO‐Au modified glassy carbon electrode surface with VCR as the template molecular, methyl acrylic acid (MAA) as the functional monomer, and ethylene glycol maleic rosinate acrylate (EGMRA) as a cross‐linker. The performance of the sensor was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) in detail. Under the optimum conditions, the fabricated sensor exhibited a linear relationship between oxidation peak current and VCR concentration over the range of 5.0×10−8–5.0×10−6 mol·L minus;1 with a correlation coefficient of 0.9952 and a detection limit (S/N=3) of 2.6×10minus;8 mol·Lminus;1. The results indicated that the imprinted polymer films exhibited an excellent selectivity for VCR. The imprinted sensor was successfully used to determine VCR in real samples with recoveries of 90% –120% by using the standard addition method.

Development and application of the tartrazine voltammetric sensors based on molecularly imprinted polymers

ABSTRACTA modified glassy carbon electrode was prepared as an electrochemical voltammetric sensor based on molecularly imprinted polymer film for tartrazine (TT) detection. The sensitive film was prepared by copolymerization of tartrazine and acrylamide on the carbon nanotube-modified glassy carbon electrode. The performance of the imprinted sensor was investigated by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy in detail. Under the optimum conditions, two dynamic linear ranges of 8 × 10−8 to 1 × 10−6 mol L−1 and 1 × 10−6 to 1 × 10−5 mol L−1 were obtained, with a detection limit of 2.74 × 10−8 mol L−1(S/N = 3). This sensor was used successfully for tartrazine determination in beverages.

A virus resonance light scattering sensor based on mussel-inspired molecularly imprinted polymers for high sensitive and high selective detection of Hepatitis A Virus

We described a novel resonance light scattering (RLS) sensor for the specific recognition of trace quantities of Hepatitis A Virus (HAV); the sensor was based on a mussel-inspired hepatitis molecularly imprinted polymer. As a recognition element, polydopamine (PDA)-coated totivirus-imprinted polymer was introduced on the surface of SiO2 nanoparticles (virus-imprinted SiO2@PDA NPs) using an efficient one-step synthesis method. The target virus was selectively captured by the imprinted polymer films, thereby increasing the RLS intensity. A simple fluorescence spectrophotometer was employed to measure the changes in the intensity. The enhanced RLS intensity (∆IRLS) was proportional to the concentration of HAV in the range of 0.04–6.0nmol∙L−1, with a low limit of detection of 8.6pmol∙L−1. The selectivity study confirmed that the resultant HAV-imprinted SiO2@PDA NPs possessed high selectivity for HAV. The sensor was successfully applied for the direct detection of additional HAV from a 20,000-fold dilution of human serum. The proposed strategy is simple, eco-friendly, highly selective, and sensitive.

Molecularly Imprinted Polymer (MIP) Film with Improved Surface Area Developed by Using Metal–Organic Framework (MOF) for Sensitive Lipocalin (NGAL) Determination

Electropolymerizable functional and cross-linking monomers were used to prepare conducting molecularly imprinted polymer film with improved surface area with the help of a sacrificial metal-organic framework (MOF). Subsequent dissolution of the MOF layer resulted in a surface developed MIP film. This surface enlargement increased the analyte accessibility to imprinted molecular cavities. Application of the porous MIP film as a recognition unit of an extended-gate field effect transistor (EG-FET) chemosensor effectively enhanced analytical current signals of determination of recombinant human neutrophil gelatinase-associated lipocalin (NGAL).

An Enzyme Free Potentiometric Detection of Reducing Sugars Based on a Poly(3-hydroxyphenylboronic acid-co-phenol) Molecularly Imprinted Polymer Modified Electrode

An enzyme free potentiometric sensor for reducing sugars (glucose and fructose) based on molecularly imprinted polymer (MIP) modified on glassy carbon electrode was systematically investigated. It was expected to work like a solid ion selective electrode (ISE) where the specific carrier are the imprinted sites. The polymer for the selective recognition of glucose and fructose were synthesized by coelectropolymerizing the 3-hydroxyphenyl boronic acid and phenol with reducing sugar (glucose or fructose) complex. The phenol could not only provide more hydroxyl but also promote the electron transfer because of its benzene ring structure and oxygen. The principle of reducing sugars detection at the MIP modified glassy carbon electrode (MIP/GCE) was to form a covalent binding which was reversible when changing the binding conditions and had a quick response to the electrochemical potential of the fabricated sensor. The imprinted polymer films covered on the electrode surface could improve the sensitivity of the sensor response remarkably. Under the optimal experimental conditions, the potential change and the concentration of glucose and fructose were linearly related from 0.75 to 18 mM. The detection limit of glucose and fructose was 0.23 mM and 0.35 mM, respectively. In addition, we had successfully evaluated the applicability of the sensitive sensor according to detect reducing sugars in practical samples.

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.

A Facile Potential-Induced In-Situ Ion Removal Trick: Fabrication of High-Selective Ion-Imprinted Film for Trivalent Yttrium Ion Separation

ABSTRACT A novel electroactive trivalent yttrium ions imprinted polymer film composed of ferricyanide embedded conductive polypyrrole (FCN/PPy) is fabricated by using a facile unipolar pulse electropolymerization (UPEP) method. The imprinted Y 3+ ions can be removed in situ from the growing film by tactfully inducing potential oscillation on the film electrode based on the electric repulsion. Cyclic Voltammetry (CV) measurements combined with Electrochemical Quartz Crystal Microbalance (EQCM) are applied to characterize quantitatively the electrochemical uptake/release process of Y 3+ ions in various electroactive ions imprinted polymer films (E-IIPs), including non-ion, divalent nickel ion and trivalent yttrium ion imprinted FCN/PPy composite films. It is found that the reversible uptake/release of Y 3+ ions can be realized by simply regulating the operating potential applied to the Y 3+ ions imprinted composite film electrode in aqueous solution of 0.1 mol L −1 Y(NO 3 ) 3 due to the unique Y 3+ ion identification capability of ion imprinted cavity and the dual driving forces resulting from both PPy and FCN. From the electrode mass change of different E-IIPs, one can speculate that parts of bound water molecules around the hydrated Y 3+ ions could move into the E-IIPs with the ions adsorption process. Two distinct stages, the adsorption of Y 3+ ions at the surface layer of E-IIPs and the transport of adsorbed ions to inner layer of E-IIPs, should be involved in the adsorption process of Y 3+ ions into the E-IIPs. For hydrated Y 3+ ions adsorbed electrochemically into the surface layer of Ni 2+ -imprinted and Y 3+ -imprinted FCN/PPy composite films, the numbers of bound water molecules with Y 3+ ions are estimated to be 1 and 4.6, respectively. It suggests that the Y 3+ ion exchange performance in E-IIPs significantly depends on the size of ion cavity and the stereochemistry of binding sites.

Molecularly imprinted electrochemical sensing interface based on in-situ-polymerization of amino-functionalized ionic liquid for specific recognition of bovine serum albumin.

A molecularly imprinted polymer film was in situ polymerized on a carboxyl functionalized multi-walled carbon nanotubes modified glassy carbon electrode surface under room temperature. This technique provides a promising imprinting approach for protein in an aqueous solution using 3-(3-aminopropyl)-1-vinylimidazolium tetrafluoroborate ionic liquid as functional monomer, N, N'-methylenebisacrylamide as crossing linker, ammonium persulfate and N,N,N',N'-tetramethylethylenediamine as initiator, and bovine serum albumin (BSA) as template. The molecularly imprinted polymerized ionic liquid film shows enhanced accessibility, high specificity and sensitivity towards BSA. Electrochemical sensing performance of the imprinted sensor was thoroughly investigated using K3Fe[CN]6/K4Fe[CN]6 as electroactive probes. Under optimal conditions, the current difference before and after specific recognition of BSA was found linearly related to its concentration in the range from 1.50×10(-9) to 1.50×10(-6) mol L(-1). The detection limit was calculated to be 3.91×10(-10) mol L(-1) (S/N=3). The practical application of the imprinted sensor was demonstrated by determining BSA in liquid milk samples.