Molecularly Imprinted Polymer Sensor Research Articles

Development of a novel sensing platform based on molecularly imprinted polymer and closed bipolar electrochemiluminescence for sensitive detection of dopamine

Abstract Electrochemiluminescence (ECL) is widely used in bioanalysis due to its outstanding performance. In this work, we proposed a new ECL sensing strategy through the combination of molecular imprinting technology (MIT) and bipolar electrode (BPE). We use 3-aminophenyl boronic acid (APBA) as the monomer and dopamine (DA) as the template molecule to fabricate the MIP sensor through one-step electropolymerization. DA was encapsulated within the polymer film during the polymerization and subsequently removed to form a molecularly imprinted polymer (MIP) for DA recognition. The MIP modified electrode was applied as the sensing electrode, which could generate the oxidation current in the presence of DA, enabling the ECL signal change of reporting cell containing Ru(bpy)32+/TPrA in the BPECL system. Therefore, the rapid analysis of DA was achieved via this c-MIP-BPECL platform. The closed BPE simplifies sample pretreatment due to the relative independence of sensing and detecting, and the enrichment and precise identification of the analytes by MIP greatly improve the sensitivity, selectivity, and stability of the bipolar system. The established platform exhibits great sensing performance for DA with a linear range of 2 × 10−7–2.6 × 10−4 M and 2.6–6.2 × 10−4 M, respectively, with the low limit of detection (LOD) of 1 × 10−7 M.

Touch-Based Stressless Cortisol Sensing.

Tracking fluctuations of the cortisol level is important in understanding the body's endocrine response to stress stimuli. Traditional cortisol sensing relies on centralized laboratory settings, while wearable cortisol sensors are limited to slow and complex assays. Here, a touch-based non-invasive molecularly imprinted polymer (MIP) electrochemical sensor for rapid, simple, and reliable stress-free detection of sweat cortisol is described. The sensor readily measures fingertip sweat cortisol via highly selective binding to the cortisol-imprinted electropolymerized polypyrrole coating. The MIP network is embedded with Prussian blue redox probes that offer direct electrical signaling of the binding event to realize sensitive label-free amperometric detection. Using a highly permeable sweat-wicking porous hydrogel, instantaneously secreted fingertip sweat can be conveniently and rapidly collected without any assistance. By eliminating time lags, such rapid (3.5min) fingertip assay enables the capture of sharp variations in cortisol levels, compared to previous methods. Such advantages are demonstrated by tracking cortisol response in short cold-pressor tests and throughout day-long circadian rhythm, along with gold-standard immunoassay validation. A stretchable epidermal MIP sensor is also described for directly tracking cortisol in exercise-induced sweat. The rapid touch-based cortisol sensor offers an attractive, accessible, stressless avenue for quantitative stress management.

Molecularly Imprinted Poly‐o‐phenylenediamine Electrochemical Sensor for Entacapone

AbstractWe have developed a molecularly imprinted polymer (MIP) electrochemical sensor for entacapone (ETC) based on an electropolymerised polyphenylenediamine (Po‐PD) on a glassy carbon electrode (GCE) surface. The direct electropolymerisation of the o‐phenylenediamine monomer (o‐PD) was carried out with ETC as a template. The steps of electropolymerization process, template removal and binding of the analyte were tested by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using [Fe(CN)6]3−/[Fe(CN)6]4 − as a redox probe. The operation of the sensor has been investigated by differential pulse voltammetry (DPV). Under optimal experimental conditions, the response of the DPV was linearly proportional to the ETC concentration between 1.0×10−7 and 5.0×10−6 M ETC with a limit of detection (LOD) of 5.0×10−8 M. The developed sensor had excellent selectivity without detectable cross‐reactivity for levodopa and carbidopa. The MIP sensor was successfully used to detect ETC in spiked human serum samples.

Low Cost, Easy to Prepare and Disposable Electrochemical Molecularly Imprinted Sensor for Diclofenac Detection.

In this work, a disposable electrochemical (voltammetric) molecularly imprinted polymer (MIP) sensor for the selective determination of diclofenac (DCF) was constructed. The proposed MIP-sensor permits fast (30 min) analysis, is cheap, easy to prepare and has the potential to be integrated with portable devices. Due to its simplicity and efficiency, surface imprinting by electropolymerization was used to prepare a MIP on a screen-printed carbon electrode (SPCE). MIP preparation was achieved by cyclic voltammetry (CV), using dopamine (DA) as a monomer in the presence of DCF. The differential pulse voltammetry (DPV) detection of DCF at MIP/SPCE and non-imprinted control sensors (NIP) showed an imprinting factor of 2.5. Several experimental preparation parameters were studied and optimized. CV and electrochemical impedance spectroscopy (EIS) experiments were performed to evaluate the electrode surface modifications. The MIP sensor showed adequate selectivity (in comparison with other drug molecules), intra-day repeatability of 7.5%, inter-day repeatability of 11.5%, a linear range between 0.1 and 10 μM (r2 = 0.9963) and a limit of detection (LOD) and quantification (LOQ) of 70 and 200 nM, respectively. Its applicability was successfully demonstrated by the determination of DCF in spiked water samples (river and tap water).

Enabling the Selective Detection of Endocrine-Disrupting Chemicals via Molecularly Surface-Imprinted "Coffee Rings".

Molecularly imprinted polymers (MIPs) represent an intriguing class of synthetic materials that can selectively recognize and bind chemical or biological molecules in a variety of value-added applications in sensors, catalysis, drug delivery, antibodies, and receptors. In this context, many advanced methods of implementing functional MIP materials have been actively studied. Herein, we report a robust strategy to produce highly ordered arrays of surface-imprinted polymer patterns with unprecedented regularity for MIP-based sensor platform, which involves the controlled evaporative self-assembly process of MIP precursor solution in a confined geometry consisting of a spherical lens on a flat Si substrate (i.e., sphere-on-flat geometry) to synergistically utilize the "coffee-ring" effect and repetitive stick-slip motions of the three-phase contact line simply by solvent evaporation. Highly ordered arrays of the ring-patterned MIP films are then polymerized under UV irradiation to achieve semi-interpenetrating polymer networks. The extraction of templated target molecules from the surface-imprinted ring-patterned MIP films leaves behind copious cavities for the recognizable specific "memory sites" to efficiently detect small molecules. As a result, the elaborated surface structuring effect, sensitivity, and specific selectivity of the coffee-ring-based MIP sensors are scrutinized by capitalizing on an endocrine-disrupting chemical, 2,4-dichlorophenoxyacetic acid (2,4-D), as an example. Clearly, the evaporative self-assembly of nonvolatile solutes in a confined geometry renders the creation of familiar yet ordered coffee-ring-like patterns for a wide range of applications, including sensors, scaffolds for cell motility, templates, substrates for neuron guidance, etc., thereby dispensing with the need of multistep lithography techniques and external fields.

Using an Electrochemical MIP Sensor for Selective Determination of 1‐Naphthol in Oilfield Produced Water

AbstractA molecularly imprinted polymer (MIP) sensor was successfully constructed on glassy carbon electrode for the determination of 1‐naphthol (1‐Nph). The sensor was constructed by electropolymerization on bare GCE in the presence of the target molecule. The recognition of 1‐Nph was conducted indirectly using [Fe(CN)6]3−/4− as redox probe. The MIP sensor presented wide linear working range and limit of detection of 1.5×10−9 mol L−1. The MIP sensor was applied for the determination of 1‐Nph in oilfield produced water. The results obtained showed good selectivity and sensitivity of the proposed sensor in terms of 1‐Nph quantification.

Molecularly imprinted polymers based on magnetically fluorescent metal–organic frameworks for the selective detection of hepatitis A virus

A novel fluorescent molecularly imprinted polymers (MIPs) sensor based on a magnetic metal–organic framework (MOF) was prepared and applied in the detection of the weakly fluorescent hepatitis A virus (HAV). Luminescent MOFs can be used as both output signals and carriers; thus, a luminescent MOF (MIL-101-NH2) was used to replace conventional quantum dots and organic dyes for generating the fluorescence output signal. The constructed MIP sensor demonstrated excellent selectivity for the template recognition entities as well as a high detection sensitivity. Over the concentration range of 0.02–2.5 nM, the sensor had a detection limit of 3 pM, and a correlation coefficient of 0.997 was calculated by plotting the concentrations of the template virus against their respective fluorescence intensities. In addition, viruses were detected within 15 min by the prepared nanoparticles and remained highly selective in binary competition assays in the presence of HAV. As a result, the method developed in this work was simple, rapid, and could be used to detect HAV qualitatively and quantitatively. It has the potential to be used as a biosensor for the detection of weakly fluorescent or non-fluorescent viruses.

Detection of chlorantraniliprole residues in tomato using field-deployable MIP photonic sensors.

A photonic sensor based on inversed opal molecular imprinted polymer (MIP) film to detect the presence of chlorantraniliprole (CHL) residue in tomatoes was developed. Acrylic acid was polymerized in the presence of CHL inside the structure of a colloidal crystal, followed by etching of the colloids and CHL elution. Colloidal crystals and MIP films were characterized by scanning electron microscopy and FT-IR, confirming the inner structure and chemical structure of the material. MIP films supported on polymethylmethacrylate (PMMA) slides were incubated in aqueous solutions of the pesticide and in blended tomato samples. The MIP sensor displayed shifts of the peak wavelength of the reflection spectra in the visible range when incubated in CHL concentrations between 0.5 and 10μgL-1, while almost no peak displacement was observed for non-imprinted (NIP) films. Whole tomatoes were blended into a liquid and spiked with CHL; the sensor was able to detect CHL residues down to 0.5μgkg-1, significantly below the tolerance level established by the US Environmental Protection Agency of 1.4mgkg-1. Stable values were reached after about 30-min incubation in test samples. Control samples (unspiked processed tomatoes) produced peak shifts both in MIP and NIP films; however, this matrix effect did not affect the detection of CHL in the spiked samples. These promising results support the application of photonic MIP sensors as an economical and field-deployable screening tool for the detection of CHL in crops.

Gut microbiota derived trimethylamine N-oxide (TMAO) detection through molecularly imprinted polymer based sensor

Trimethylamine N-oxide (TMAO), a microbiota-derived metabolite has been implicated in human health and disease. Its early detection in body fluids has been presumed to be significant in understanding the pathogenesis and treatment of many diseases. Hence, the development of reliable and rapid technologies for TMAO detection may augment our understanding of pathogenesis and diagnosis of diseases that TMAO has implicated. The present work is the first report on the development of a molecularly imprinted polymer (MIP) based electrochemical sensor for sensitive and selective detection of TMAO in body fluids. The MIP developed was based on the polypyrrole (PPy), which was synthesized via chemical oxidation polymerization method, with and without the presence of TMAO. The MIP, NIP and the non-sonicated polymer (PPy-TMAO) were separately deposited electrophoretically onto the hydrolyzed indium tin oxide (ITO) coated glasses. The chemical, morphological, and electrochemical behavior of MIP, non-imprinted polymer (NIP), and PPy-TMAO were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and electrochemical techniques. The detection response was recorded using differential pulse voltammetry (DPV), which revealed a decrease in the peak current with the increase in concentration of TMAO. The MIP sensor showed a dynamic detection range of 1–15 ppm with a sensitivity of 2.47 µA mL ppm−1 cm−2. The developed sensor is easy to construct and operate and is also highly selective to detect TMAO in body fluids such as urine. The present research provides a basis for innovative strategies to develop sensors based on MIP to detect other metabolites derived from gut microbiota that are implicated in human health and diseases.

Molecularly imprinted polypyrrole sensors for the detection of pyrene in aqueous solutions

Recently, electrochemical sensors have emerged as tools for polyaromatic hydrocarbons (PAH) detection that are cost-effective, easy to produce and use, highly selective and sensitive, and with good reproducibility. Polypyrrole may be easily produced from polymerization of pyrrole, by chemical as well as electrochemical methods, to produce dimensionally stable semi-conductive polymer materials, under mild synthesis conditions. In this study, polypyrrole was used as the stable molecular framework within which to create an imprint of the desired polyaromatic hydrocarbon, in situ, at glassy carbon electrodes. The molecularly imprinted polymer (MIP) sensors were washed to remove the imprint and subsequently characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), and cyclic voltammetry (CV). The MIP sensors were then applied to the detection of pyrene and non-imprinted polymers (NIP) sensors were also evaluated for comparison with the MIP sensors. Calibration curves obtained for the detection of the pyrene at the MIP sensors in aqueous media reported limits of detection (LOD) of 2.28 × 10−7 M for pyrene and limit of quantification (LOQ) of 6.92 × 10−7 M (n = 3). The sensitivity of the MIP sensors (32.53 A/M) determined from the slopes of the calibration curves reported twice the value measured for NIP sensors (14.48 A/M). The selectivity of the MIP sensors was further evaluated in the presence of a second PAH with the same number of rings as the imprinted PAH, i.e., chrysene, to evaluate the selectivity of the MIP sensor towards shape and size of the analyte.

An electrochemical sensor based on molecularly imprinted polymer conjointly with a voltammetric electronic tongue for quantitative diphenyl phosphate detection in urine samples from cosmetic product users

This research work deals with the diphenyl phosphate (DPP) detection in urine samples using a molecularly imprinted polymer (MIP) sensor and a voltammetric electronic tongue (VE-tongue). In this regard, gold nanoparticles (Au-NPs) and titanium dioxide (TiO2) were first designed onto a screen-printed carbon electrode (SPCE). Then, the sensor was fabricated by bulk-polymerizing methacrylic acid in the presence of DPP molecules as template. To achieve a sensor with optimal performance, crucial experimental parameters were well optimized. This sensor exhibits good linearity over a range of 0.1–24.3 ng/mL (R2 = 0.98) as well as high sensitivity (0.141 μA/ng.mL−1) and low detection limit (LOD =0.063 ng/mL). Moreover, suitable stability and selectivity were achieved with reproducibility and repeatability reached a RSD of 2.3 and 3.02 %, respectively. For the DPP determination in urine samples from nail polish users, the sensor reveals good results in concordance with spectrophotometry as reference method with a (RSD ≤ 4%). Secondly, qualitative analysis was performed by a VE-tongue combined with chemometrics to classify urine samples of nail polish users. Partial least squares (PLS) method supplied prediction models achieved from the both systems data with a regression coefficient (R = 0.99). Accordingly, the MIP sensor and VE-tongue could be viable electrochemical tools for cosmetic applications.

Highly sensitive electrochemical determination of the SARS-COV-2 antigen based on a gold/graphene imprinted poly-arginine sensor.

The global COVID-19 pandemic starting at 2020 induced by the severe acute respiratory syndrome coronavirus 2 virus (SARS-CoV-2) has revealed a very pressing need for rapid, affordable and effective diagnosis for epidemic management and control. Although several commercialized analytical methods (e.g., reverse transcription polymerase chain reaction and enzyme linked immunosorbent assay) have been developed for detecting SARS-CoV-2, they are expensive and time-consuming. Most recently, low-cost molecularly imprinted polymer (MIP)-based sensors have received attention. In this study, by introducing gold/graphene (Au/Gr) nanohybrids to modify a screen-printed carbon electrode (SPCE) and using arginine as the functional monomer, a simple and highly sensitive MIP sensor was proposed to detect SARS-CoV-2 nucleocapsid protein (ncovNP). By optimizing various influencing factors, the proposed MIP sensor shows wide linear range and low detection limit for ncovNP owing to excellent electrical property and large surface of Au/Gr and specific recognition ability of MIP, revealing important potential application for the effective early diagnosis of COVID-19.

One-step Synthesis of Ultrasmall Platinum Nanoparticles Supported on Amino-Functionalized Graphene to Create an Electrochemical Molecularly Imprinted Polymer Sensor for Fluxapyroxad

One-step Synthesis of Ultrasmall Platinum Nanoparticles Supported on Amino-Functionalized Graphene to Create an Electrochemical Molecularly Imprinted Polymer Sensor for Fluxapyroxad

A Molecularly Imprinted Polymer Sensor Based on the Electropolymerization of p-Aminothiophenol-Functionalized Au Nanoparticles Electrode for the Detection of Nonylphenol

A Molecularly Imprinted Polymer Sensor Based on the Electropolymerization of p-Aminothiophenol-Functionalized Au Nanoparticles Electrode for the Detection of Nonylphenol

An electrochemical molecularly imprinted polymer sensor for rapid and selective food allergen detection

Food allergies are a serious and rising public health concern. The potentially fatal consequence of food allergies makes managing them costly and anxiety-inducing. Rapid, on-site detection of allergenic ingredients in foods would greatly improve the health and quality of life of food allergy sufferers. This work demonstrates the feasibility of such a device using molecularly imprinted polymers (MIPs). The MIP sensor can detect allergenic soy markers at concentrations as low as 100 parts-per-billion, two orders of magnitude below clinically relevant thresholds, in both controlled and complex food samples. Sensor performance was qualitatively validated with commercially available soy allergen detection lateral flow devices (LFDs). The outcome of this application will address a long-standing analytical challenge to achieving fast, cost-effective, and scalable methods for direct detection of allergen tracers in food analysis.

Non-enzymatic lactose molecularly imprinted sensor based on disposable graphite paper electrode

Lactose (LAC) is a disaccharide - major sugar, present in milk and dairy products. LAC content is an important indicator of milk quality and abnormalities in food industries, as well as in human and animal health. The present study reports the development of an innovative imprinted voltammetric sensor for sensitive detection of LAC. The sensor was constructed using electropolymerized pyrrole (Py) molecularly imprinted polymer (MIP) on graphite paper electrode (PE). The MIP film was constructed through the electrosynthesis of polypyrrole (PPy) in the presence of LAC (template molecule) on PE (PPy/PE). To optimize the detection conditions, several factors affecting the PPy/PE sensor performance were assessed by multivariate methods (Plackett–Burman design and central composite design). Under optimized conditions, the proposed analytical method was applied for LAC detection in whole and LAC-free milks, where it demonstrated high sensitivity and selectivity, with two dynamic linear ranges of concentration (1.0–10 nmol L−1 and 25–125 nmol L−1) and a detection limit of 0.88 nmol L−1. The MIP sensor showed selective molecular recognition for LAC in the presence of structurally related molecules. The proposed PPy/PE sensor exhibited good stability, as well as excellent reproducibility and repeatability. Based on the results obtained, the PPy/PE is found to be highly promising for sensitive detection of LAC.

Melamine Recognition: Molecularly Imprinted Polymer for Selective and Sensitive Determination of Melamine in Food Samples.

In this study, a sensitive and selective sensor is constructed to measure the melamine (MEL) using molecular imprinting polymer (MIP) technique. Chemical and electrochemical techniques are used to construct the MIP and quantitative measurements. The constructed sensor was modified with GO-Fe3O4@SiO2 nanocomposite. Screening and optimization of factors are done using statistical methods, including Plackett–Burman design (PBD) and central composite design (CCD). Under the optimized conditions, an MIP sensor showed a linear range from 5.0 × 10−7 to 1.0 × 10−5 M MEL concentration with a correlation coefficient (R2) of 0.9997. The limit of detection was obtained (0.028 µM) with a highly reproducible response (RSD 2.15%, n = 4). The electrochemical sensor showed good results for the determination of MEL in food samples.

A "Single-Use" Ceramic-Based Electrochemical Sensor Chip Using Molecularly Imprinted Carbon Paste Electrode.

An inexpensive disposable electrochemical drug sensor for the detection of drugs (vancomycin, meropenem, theophylline, and phenobarbital) is described. Molecularly imprinted polymer (MIP) templated with the target drugs was immobilized on the surface of graphite particles using a simple radical polymerization method and packed into the working electrode of a three-electrode ceramic-based chip sensor. Differential pulse voltammetry (DPV) was used to determine the relationship between the response current and the concentration of the targeted drug while using one sensor chip for one single operation. The time required for each DPV measurement was less than 2 min. Concentrations corresponding to the therapeutic range of these drugs in plasma were taken into account while performing DPV. In all the cases, the single-used MIP sensor showed higher sensitivity and linearity than non-imprinted polymer. The selectivity test in drugs with a structure similar to that of the target drugs was performed, and it was found that MIP-based sensors were more selective than the untreated ones. Additionally, the test in whole blood showed that the presence of interfering species had an insignificant effect on the diagnostic responses of the sensor. These results demonstrate that the disposable MIP-sensor is promising for quick and straightforward therapeutic drug monitoring to prevent the toxic side effects and the insufficient therapeutic effect due to the overdose and underdose, respectively.

Electrochemical Determination of Naloxone Using Molecularly Imprinted Poly(para-phenylenediamine) Sensor

A molecularly imprinted polymer (MIP)-based electrochemical sensor featuring an electrochemically grafted para-phenylenediamine functional monomer on a reduced graphene oxide-gold nanoparticles composite modified screen printed electrode is reported. The morphology and properties of the sensing material were characterized with microscopy, spectroscopy and electrochemical techniques. A number of factors affecting the performance of the MIP sensor were examined and optimized. Under an optimized condition, the imprinted electrochemical sensor yielded homogenous naloxone binding sites with a dissociation constant of 8.6 μM, and responded linearly up to 8 μM naloxone, with a limit of detection of 0.16 μM. The sensor showed good run-to-run repeatability and batch-to-batch performance reproducibility with relative standard deviation of 5.7%–9.6% (n = 4) and <9% (n = 3), respectively. The imprinted sensor retained 95% and 85% of its performance when stored at ambient conditions for one and two weeks, respectively, demonstrating the sensor’s good stability. Selectivity experiments showed that both the MIP sensor and non-imprinted polymer electrode had minimal response (<25%) to equal concentrations of structurally similar compounds such as morphine, naltrexone and noroxymorphone, indicating good selectivity of the MIP sensor towards naloxone. The MIP sensor was successfully used to quantify naloxone in artificial urine samples, yielding recoveries greater than 92%.

An electrochemical molecularly imprinted sensor based on chitosan capped with gold nanoparticles and its application for highly sensitive butylated hydroxyanisole analysis in foodstuff products

One of the most widely used synthetic antioxidants in food, butylated hydroxyanisole (BHA) has raised serious concerns due to its potential toxic effects on human health. Hence, elaboration of simple, effective and sensitive methods for BHA detection is pressing. In this regards, the present research work highlights a facile, simple, and fast synthesis approach for the development of an electrochemical sensor for the analysis of BHA in foodstuffs. In this study, the chitosan (CS) capped with gold nanoparticles (AuNPs) were self-assembled on a screen-printed carbon electrode (SPCE) and complete the elaboration of the molecularly imprinted polymer (MIP) sensor in the presence of BHA as templates. The electrochemical behaviour of the MIP sensor was investigated by using electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and cyclic voltammetry (CV). Similarly, the morphology of the electrodes surface of the different elaboration steps was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and atomic force microscopy (AFM). In addition, the obtained results demonstrate satisfactory sensitivity and selectivity to BHA compared to interfering species, including ascorbic acid and citric acid. Under optimal experimental conditions, the MIP sensor exhibits responses proportional to concentrations over a range of 0.01–20 μg mL−1, with a low detection limit (LOD) of 0.001 μg mL−1 (signal-to-noise ratio S/N = 3). Besides, the reproducibility, stability, and repeatability of the MIP sensor were proven. Taking into account all these outcomes, the MIP sensor well demonstrates its ability towards the determination of BHA in food samples with a relative standard deviation (RSD ≤ 8%). Spectrophotometry was utilized as a validation method. Partial least squares (PLS) prediction models were constructed from the MIP sensor and spectrophotometer data with a regression coefficient (R = 0.99). According to the achieved outcomes, the MIP sensor could be a viable tool for food control.