MXene–molecularly imprinted polymer electrochemical sensors: A systematic review and meta-analysis

Polymeric membrane sensors based on molecular imprinted polymers (MIPs) have been attractive analytical tools for detecting organic species. However, the MIPs in electrochemical sensors developed so far are usually prepared by in situ polymerization of pre-polymers and non-covalent adsorption on the surface of the working electrode. Meanwhile, the MIPs in the electrochemical sensors developed are typically made of a non-conductive polymer film. This results in a relatively low current due to the lack of electron transfer. Additionally, the smoothness of the traditional electrochemical substrate results in a low specific surface area, which reduces the sensitivity of the electrochemical sensor. Here, we describe a novel electrochemical sensor with a conductive interface and MIPs modification. The electrochemical sensor was modified by covalent coupled layer by layer self-assembly with the imprinted polymer film. The incorporation of these two conductive functional materials improves the conductivity of the electrodes and provides interface support materials to obtain high specific surface area. By using 2,4,6-trichlorophenol as the model, the sensitivity of the developed conductive sensor was greatly improved compared to that of the traditional MIPs sensor. We believe that the proposed MIPs-based sensing strategy provides a general and convenient method for making sensitive and selective electrochemical sensors.

Introduction Naloxone, (5α)-4,5-epoxy,3,14-dihydroxy17(2-propenyl) morphinan-6-one, (Figure 1) is a synthetic opioid receptor antagonist mainly used for the treatment of opioid overdose and to reduce constipation caused by orally administered opioid therapy [1]. A number of analytical methods have been reported for the detection of naloxone, mainly by high performance liquid chromatography [2], high performance liquid chromatography coupled with mass spectrometry [3] and chemiluminescence [4]. However, the methods are costly, time consuming, produce large amounts of liquid waste which is not environment friendly, and not appropriate for field use. Electrochemical sensor platforms, however, are attractive for handheld detection and field use due to their low sample volume requirement, simplicity and compactness. In this work, we report on the development of simple, yet sensitive and selective electrochemical sensor for naloxone detection using molecular imprinted polymer (MIP) and screen printing electrodes. Method The MIP preparation was carried out via in situ electropolymerization of a solution composed of the functional monomer, p-phenylenediamine (pPD), and the template (naloxone) in phosphate citrate buffer at pH 6 on a screen printed carbon electrode that was modified with reduced graphene oxide (rGO) and gold nanoparticle (AuNPs) (Figure 2). Several parameters controlling the preparation and performance of the MIP sensor (including pH, the molar ratio between monomer and template molecules, the cycle number of electropolymerization, and incubation time of the modified electrode on the sensing performance) were studied and optimized. After electropolymerization, naloxone molecules were removed from the MIP using methanol/HCl solution to generate binding sites that were complimentary in size, shape and functionality to naloxone molecules for later detection. Non-imprinted polymer (NIP) modified electrodes were prepared using the optimized procedure but in the absence of naloxone to examine the selectivity of the MIP sensor. The electrochemical behavior of naloxone at MIP and NIP sensors was evaluated by differential pulse voltammetry. Results and Conclusions The morphology and properties of the sensing material were characterized with scanning electron microscopy, Raman spectroscopy, and atomic force microscope. Under an optimized condition, the MIP electrochemical sensor responded linearly to naloxone concentration between 0.5 μM to 8 μM, with a detection limit of 0.23 μM. The introduction of rGO and AuNPs hybrid materials significantly improved the sensor’s performance. The selectivity of the MIP sensor towards naloxone was examined using morphine, naltrexone and noroxymorphone as interferents. The result of the selectivity experiment showed that the imprinted electrode has a good response and selectivity towards naloxone. To further demonstrate the potential of the developed MIP-based naloxone sensor for practical applications, the sensor was tested for the detection of naloxone in spiked urine samples. Recoveries of up to 97.0% were recorded, demonstrating the reliability and accuracy of the sensor for naloxone detection in bodily fluids.

Molecularly imprinted polymers (MIPs) have emerged as robust and versatile recognition elements for electrochemical sensing due to their high chemical and mechanical stability, cost-effective fabrication, and excellent selectivity toward target analytes. In recent years, MIP-based electrochemical sensors have gained significant attention for the detection of pharmaceutical contaminants in wastewater, addressing growing environmental and public health concerns. This review provides a comprehensive overview of the fundamental principles of molecular imprinting Emphasis is placed on fabrication strategies and electrochemical detection techniques, including cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Furthermore, it discusses imprinting mechanisms for different classes of contaminants, matrix effects, and other challenges. By critically analyzing recent applications, this work highlights key factors influencing sensor performance, such as sensitivity, selectivity, and detection limits. Finally, we touch on future perspectives, focusing on the development of more reliable, scalable, and environmentally sustainable sensing platforms for real-world wastewater monitoring.

Molecularly imprinted polymers (MIPs) belong to the illustrious examples of bio-mimicking recognizing materials.1 They have found numerous applications in the fabrication of selective chemosensors.2 Their analytical parameters, such as sensitivity, selectivity, and detectability, are almost as high as those of biosensors. Additionally, MIP based chemosensors are superior to biosensors concerning their ease of fabrication, durability, and tolerance to harsh conditions, including elevated or decreased temperature, high ionic strength, extreme pH values, the presence of heavy metal ions and organic solvents in the samples. Conductive MIPs have recently become more frequently applied. That is mainly due to the easy control of MIPs deposition as thin films by electropolymerization.3 For the electrochemical determination of non-electroactive analytes, some external redox probe is usually added to the test solution. It is assumed that target analyte molecules' binding into molecular cavities causes MIP film swelling or shrinking. According to the so-called "gate effect" mechanism, this polymer "breathing" causes changes in the redox probe permeability through an MIP film, thus changing faradaic current corresponding to the redox probe's reduction or oxidation in cyclic voltammetry (CV) and differential pulse voltammetry (DPV) determinations.4-5 This mechanism is operative for nonconductive MIP films. Another mechanism may be considered for surface imprinted macromolecular compounds, e.g., proteins. A drop in the faradaic current of the redox probe accompanying protein adsorption originates from physical blocking of the electrode surface by their bulky nonconductive molecules.6 But both of these mechanisms seem to be invalid in case of electrochemical sensors based on conductive MIP films. In our previous studies, we demonstrated that a drop in the DPV current, caused by the appearance in a solution of an analyte, at conductive MIP film-coated electrodes might originate not from hindering the diffusion of the redox probe through the film but from changes in electrochemical properties of the film itself 7. Suppose the redox probe diffusion through the MIP film is not a decisive parameter for the faradaic current involving. Then, in the, e.g., DPV, determinations of electroinactive analytes at conductive MIP film-coated electrodes, this diffusion may be eliminated. For that the redox probe could be immobilized inside the MIP film matrix. Herein, we propose to deposit a self-reporting MIP film and apply it for fabrication of the selective electrochemical sensor determining the target analyte in the redox probe free test solutions. For that purpose, a ferrocene redox probe was covalently immobilized in a bis-bithiophene polymer molecularly imprinted with the p-synephrine template. Simultaneously, this polymer was deposited on the Pt electrode as a thin film. After the template extraction from the film, the analyte was determined with differential pulse voltammetry (DPV) in a redox probe free solution. That was possible because the internal ferrocene redox probe generated the DPV analytical signal. The thickness and morphology of the film were crucial for the sensor's performance. The mechanism of this redox self-reporting MIP film-based chemosensor was examined with electrochemical methods, simultaneous piezomicrogravimetry and electrochemistry at an electrochemical quartz crystal microbalance, and surface plasmon resonance spectroscopy. The devised chemosensor was applied for selective p-synephrine determination in a concentration range of 2.0 to 75 nM. References Cieplak, M.; Kutner, W., Artificial biosensors: How can molecular imprinting mimic biorecognition? Trends Biotechnol. 2016, 34 (11), 922-941. Uzun, L.; Turner, A. P. F., Molecularly-imprinted polymer sensors: realising their potential. Biosens. Bioelectron. 2016, 76, 131-144. Huynh, T.-P.; Sharma, P. S.; Sosnowska, M.; D'Souza, F.; Kutner, W., Functionalized polythiophenes: Recognition materials for chemosensors and biosensors of superior sensitivity, selectivity, and detectability. Prog. Polym. Sci. 2015, 47, 1-25. Yoshimi, Y.; Narimatsu, A.; Nakayama, K.; Sekine, S.; Hattori, K.; Sakai, K., Development of an enzyme-free glucose sensor using the gate effect of a molecularly imprinted polymer. J. Artif. Organs 2009, 12 (4), 264-270. Sharma, P. S.; Garcia-Cruz, A.; Cieplak, M.; Noworyta, K. R.; Kutner, W., 'Gate effect' in molecularly imprinted polymers: the current state of understanding. Curr. Opin. Electroche. 2019, 16, 50-56. Moreira, F. T. C.; Dutra, R. A. F.; Noronha, J. P. C.; Fernandes, J. C. S.; Sales, M. G. F., Novel biosensing device for point-of-care applications with plastic antibodies grown on Au-screen printed electrodes. Sens. Actuators, B 2013, 182, 733-740. Lach, P.; Cieplak, M.; Majewska, M.; Noworyta, K. R.; Sharma, P. S.; Kutner, W., "Gate Effect" in p-Synephrine Electrochemical Sensing with a Molecularly Imprinted Polymer and Redox Probes. Anal. Chem. 2019, 91 (12), 7546-7553. Figure 1

The great variety and the low concentrations of contaminants in environmental water are great analytical challenges. Both voltammetric and potentiometric electrochemical sensors allow the sensitive online measurement by simple instrumentation; however, they are restricted to electroactive substances, and their specificity is frequently not sufficient. The combination of electrochemical sensors with biomimetic recognition elements, e.g., molecularly imprinted polymers (MIPs) or aptamers, has the potential for highly sensitive and specific analysis. In the MIP synthesis, functional monomers interact with the target analyte (so-called template) to the pre-polymerization complex. It is “frozen” by the formation of a polymer network around the template. Subsequently, the template is removed, and binding cavities are formed in the polymer: they mirror the size, shape, and functionality of the template, which is preferentially bound from complex media. Electrochemical MIP sensors unify the potentials of synthetic binders with simple electrochemical instrumentation. This chapter presents the status of MIP-based electrochemical sensors for environmentally relevant analytes according to the type of recognition element: Binding MIPs for low-molecular-weight analytes; Catalytically active MIPs; (Reloadable) enzyme-MIP sensors.

Drug detection in biological solutions is essential in studying the pharmacokinetics of the body. Electrochemical detection is an accurate and rapid method, but measuring multiple drugs that react at similar potentials is challenging. Herein, we developed an electrochemical sensor using a boron-doped diamond (BDD) electrode modified with a molecularly imprinted polymer (MIP) to provide specificity in drug sensing. The MIP is a polymer material designed to recognize and capture template molecules, enabling the selective detection of target molecules. In this study, we selected the anticancer drug doxorubicin (DOX) as the template molecule. In the electrochemical measurements using an unmodified BDD, the DOX reduction was observed at approximately -0.5 V (vs Ag/AgCl). Other drugs, i.e., mitomycin C or clonazepam (CZP), also underwent a reduction reaction at a similar potential to that of DOX, when using the unmodified BDD, which rendered the accurate quantification of DOX in a mixture challenging. Similar measurements conducted in PBS using the MIP-BDD only resulted in a DOX reduction current, with no reduction reaction observed in the presence of mitomycin C and CZP. These results suggest that the MIP, whose template molecule is DOX, inhibits the reduction of other drugs on the electrode surface. Selective DOX measurement using the MIP-BDD was also possible in human plasma, and the respective limits of detection of DOX in PBS and human plasma were 32.10 and 16.61 nM. The MIP-BDD was durable for use in six repeated measurements, and MIP-BDD may be applicable as an electrochemical sensor for application in therapeutic drug monitoring.

Constant potential prepared molecularly imprinted electrochemical sensors for in vivo analysis of electroactive indole-3-acetic acid in tomato fruits.

Self-supported Fe3N-Co2N nanoarray with high electric conductivity and large surface area was prepared for growth of MIPs and further constructing a sensitive and stable electrochemical sensor. For the evaluation of its performance, Fe3N-Co2N is used as sensing electrode material, and AMP is used as template molecule to construct the MIP electrochemical sensor. Under the optimized conditions, the developed MIPs electrochemical sensor detects AMP with a low detection limit of 3.65 × 10-10molL-1 and shows outstanding reproducibility and stability. When the MIPs electrochemical sensor was applied to detect AMP in milk samples via standard addition method, the recovery within 97.06-102.43% with RSD of 1.05-2.11% was obtained. The fabrication of MIPs electrochemical sensor is highly promising for sensitive and selective electrochemical measurement and food safety testing. This work can provide theoretical guidance for truly challenging problems. Graphical abstract Principle diagram of MIP-EC sensor for detecting AMP Molecular imprinted polymers (MIPs) are widely performed for construction of electrochemical (EC) sensors especially for detecting small molecules in complex environment. However, the large-scale and robust preparation of MIPs in situ on sensor platform limits their practical applications. We fabricated a MIPs EC sensor based on Fe3N-Co2N in situ grown on carbon cloth (CC) as the substrate platform (Fe3N-Co2N/CC) combining with MIPs as the target recognition element for the label-free detection of AMP. Under the optimal conditions, the developed MIPs EC sensor can detect AMP with a low detection limit of 3.65 × 10-10molL-1. When the AMP in milk is detected by the proposed EC sensor, it shows ideal results. Therefore, the use of self-supported Fe3N-Co2N nanoarray as the platform for the fabrication of MIPs EC sensors is highly promising for sensitive and selective EC measurement and point-of-care testing.

<P>Background: The electrochemical sensing of drugs in pharmaceutical formulations and biological matrices using molecular-imprinting polymer (MIP) as a recognition element combined with different electrochemical signal transduction has been widely developed. The MIP electrochemical sensors based on nanomaterials such as graphene, carbon nanotubes, nanoparticles, as well as other electrode modifiers incorporated into the MIPs to enhance the performance of the sensor, have been discussed. The recent advances in enantioselective sensing using MIP-based electrochemical sensors have been described. </P><P> Methods: The molecular imprinting has more than six decades of history. MIPs were introduced in electrochemistry only in the 1990s by Mosbach and coworkers. This review covers recent literature published a few years ago. The future outlook for sensing, miniaturization and development of portable devices for multi-analyte detection of the target analytes was also given. </P><P> Results: The growing pharmaceutical interest in molecularly imprinted polymers is probably a direct consequence of its major advantages over other analytical techniques, namely, increased selectivity and sensitivity of the method. Due to the complexity of biological samples and the trace levels of drugs in biological samples, molecularly imprinted polymers have been used to improve the response signal, increase the sensitivity, and decrease the detection limit of the sensors. The emergence of nanomaterials opened a new horizon in designing integrated electrochemical systems. The success of obtaining a high-performance electrochemical sensor based on MIPs lies in the kind of material that builds up the detection platform. </P><P> Conclusion: The novel approaches to produce MIP materials, combined with electrochemical transduction to develop sensors for screening different pharmaceutically active compounds have been overviewed. MIPs may appear indispensable for sensing in harsh conditions, or sensing that requires longterm stability unachievable by biological receptors. The electrochemical sensors provide several benefits including low costs, shortening analysis time, simple design; portability; miniaturization, easy-touse, can be tailored using a simple procedure for particular applications. The performance of sensor can be improved by incorporating some conductive nanomaterials as AuNPs, CNTs, graphene, nanowires and magnetic nanoparticles in the polymeric matrix of MIP-based sensors. The application of new electrochemical sensing scaffolds based on novel multifunctional-MIPs is expected to be widely developed and used in the future.</P>

The diverse molecules present in fruits significantly influence their flavor and can serve as essential biomarkers to monitor the condition of fruits. Among the important biomarkers, furaneol (2,5-Dimethyl-4-hydroxy-3(2H)-furanone) is a notable aroma compound found in various fruits such as strawberry, pineapple, mango, and other food sources. [1] Furaneol is critical in the aroma intensities of fruits and sweet flavor independent of sugar contents. Its low organoleptic threshold allows even small amounts to have a significant impact on the overall flavor. The amount of furaneol in fruits is widely regarded as a vital indicator to monitor the fruit condition, as its levels vary during the ripening stages. Consequently, furaneol is considered an essential marker for identifying the origin of food products, optimizing food production processes, and controlling fruit quality. While the relationship between fruit conditions and furaneol concentration is evident, the methods for quantifying these furaneol concentrations rely on expensive and time-consuming techniques such as high-performance chromatography (HPLC) and gas chromatography (GC). [2] Therefore, developing a real-time electrochemical sensor for cost-effective, stable, rapid, and sensitive detection of furaneol is a great challenge for efficient assessment of fruit quality.Detection of furaneol through electrochemical methods offers a promising solution to these challenges. Electrochemical sensors can be the most attractive approach due to their rapid response, simple operation, easy fabrication process, low cost, and compact design. Furthermore, the electrochemical sensor approach can investigate the redox activity and charge transfer properties by reacting with furaneol, followed by redox activities and protonation to provide a clear understanding of the detection mechanism. Polyaniline (PANI) is one of the most frequently utilized conducting polymers in electrochemical sensors owing to their straightforward synthesis, environmental stability, and tunable surface charge properties through dopant modifications. [3] Despite these advantages, PANI-based electrochemical sensors face challenges in the selective detection of furaneol because of their susceptibility to interference from multiple molecules. Fruits contain various compounds, which can pose challenges for PANI-based sensors in accurately detecting the furaneol analyte. To overcome this challenge, molecularly imprinted polymers (MIP) were employed to PANI. MIPs, often referred to as plastic antibodies, mimic the affinity of biological antibodies for selective and efficient detection of target compounds. [4] For electrochemical sensor utilization, it is essential to use sensing materials within the semi-conducting range to observe charge transfer properties driven by redox activities. However, MIPs typically possess insulating electrical properties. Therefore, it is necessary to combine highly selective MIPs with PANI while maintaining the semi-conducting electrical properties of PANI.In this study, we developed electrochemical sensors utilizing MIP-based PANI with semi-conducting electrical properties using a novel interfacial polymerization technique. The higher density of PANI than methacrylic acid functional monomer enabled polymerized functional monomer to form an adherent coating on the PANI surface while preserving its electrical conductivity. Our findings demonstrate the specific recognition element forming selective binding sites to achieve sensitive and selective detection of furaneol targets. The comparison between MIP and the non-imprinted polymer (NIP)-based PANI shows a strong interaction between the furaneol target and the MIP recognition elements with 40 times enhanced sensing properties. The furaneol sensing mechanism was elucidated through the interaction between the gas-type furaneol and the charge carriers of MIP-PANI for the gas sensors, [5] as well as current density changes of PANI induced by protonated furaneol targets for liquid sensors. [6] Furthermore, field applicability was evaluated by comparing the sensing performance of the developed MIP-based sensors for real strawberries with a commercial e-nose system. The results highlight the potential to offer a rapid, durable, and cost-effective platform for specific recognition of furaneol in field applications. References Aubert, C., S. Baumann, and H. Arguel, Optimization of the analysis of flavor volatile compounds by liquid − liquid microextraction (LLME). Application to the aroma analysis of melons, peaches, grapes, strawberries, and tomatoes. Journal of agricultural and food chemistry, 2005. 53(23): p. 8881-8895.Yuan, J.-P. and F. Chen, Separation and identification of furanic compounds in fruit juices and drinks by high-performance liquid chromatography photodiode array detection. Journal of agricultural and food chemistry, 1998. 46(4): p. 1286-1291.Aydemir, N., J. Malmström, and J. Travas-Sejdic, Conducting polymer based electrochemical biosensors. Physical Chemistry Chemical Physics, 2016. 18(12): p. 8264-8277.BelBruno, J.J., Molecularly imprinted polymers. Chemical reviews, 2018. 119(1): p. 94-119.Kim, W., et al., Molecularly Imprinted Chemiresistive Sensor for Specific Recognition of Furaneol as a Biomarker of Strawberry Flavor Conditions. ACS sensors, 2023. 8(4): p. 1542-1549.Kim, W., et al., Development of Molecularly Imprinted Polymer Electrochemical Sensors for Strawberry Sweetness Biomarker Detection. ACS Applied Polymer Materials, 2024. 6(14): p. 8084-8092.

Molecularly Imprinted Polymers (MIPs) is a polymer that binds together to form a specific binding site that is selective for certain analytes. Its high stability, its synthesize simplicity, and it can ease costs significantly make it was applied widely as a receptor instead of antibodies or enzymes. MIPs can be re-developed into MIPs nanoparticles (MIP-NPs) which have greater potential. MIPs use in electrochemical sensors have relevant applications in daily life and have been tested in human samples. Electrochemical sensors have been successfully functioned with MIP-NPs leading to real-time monitoring of drugs, pesticides, environmental contaminants, and secondary metabolites, as well as molecules with biological relevance. The aim of this review is to summarize the developments and applications of MIP-NPs as a selective recognition component in electrochemical sensors with special emphasis on their analytical applications.

This dissertation focused on the development of analytical sensors for quantitative analysis of various electroactive compounds such as β-agonists and neurotransmitters, which could be considered as important indicators for food-safety monitoring, drug doping control in sports, clinical testing, and health care inspection. Up to date, colorimetry and electrochemistry are the two attractive approaches that have extensively been employed as analytical sensing tools, due to their simple operation and interpretation, fast analysis time, good ability of coupling with other techniques, and high capability of miniaturization. With these two detection platforms, this dissertation would then be divided into two main parts: (1) The development of integrated platforms for the colorimetric sensor and its application; and (2) The development of integrated platforms for the electrochemical sensor and its application. In the first section, the transparency-based colorimetric sensor for salbutamol determination relying on the redox reaction was developed. Digital camera was used as the optical readout, and the noticeable color change, induced through the oxidation of salbutamol by strongly oxidizing permanganate (KMnO4), could then be monitored. In the second part, the selective electrochemical sensors were developed and classified into three sub-sections. For the first sub-section, the anti-fouling PdNPs-modified BDD electrode was combined with UHPLC separation system for the simultaneous determination of four β-agonists. The remarkable improvement in analytical efficiency regarding fast analysis and fouling resistance capability was attained. In the second sub-section, the molecularly imprinted polymer (MIP) with selective recognition of salbutamol was electrochemically synthesized and immobilized onto the polyaniline (PANI)-modified screen-printed graphene electrode. A great enhancement in selectivity of the proposed sensing system towards the oxidation of the target analyte (Salbutamol ; SAL), could be obtained. Lastly, in the third sub-section, the synergistically electrocatalytic activity and the selectivity improvement of the trimetallic CuNiAu alloy towards the oxidation of monoamine neurotransmitters were first examined. The corresponding trimetallic CuNiAu composite was modified onto the screen-printed graphene electrode, and the developed electrochemical sensor was subsequently used for the simultaneous determination of serotonin (5-HT) and norepinephrine (NE). The enhanced analytical performance regarding the sensitivity and selectivity of this sensor could be achieved. Conclusively, the developed colorimetric and electrochemical sensors thoroughly studied in this dissertation could offer good sensitivity, high selectivity, affordability, simplification, and high-throughput analysis with great potential to be further developed for on-site applications.

The development of molecularly imprinted polymers (MIPs) and the applications for them have attracted a great deal of interest during the last two decades. MIPs are generally used in different fields, specially molecularly imprinted electrochemical sensors (MIECS), due to their particular design and specific detection abilities [1]. The advantages of an electrochemical MIP sensor include low cost, easy operation, rapid response time and excellent potential for miniaturization and construction for portable equipment applications [2]. In the scope of this work, we performed that electropolymerization of IrO2 as an electrochromic material on an indium tin oxide (ITO) glass substrate and electrosynthesis on this electrode using pyrrole as a functional monomer in the presence of acetamiprid as template were used to create the electrochromic molecular imprinted polymer sensor (MIP/IrO2/ITO). With the created electrochromic MIP sensor, it is intended to create a selective pesticide sensor by utilizing molecular imprinted polymer (MIP) technology, and to detect with the naked eye by color change depending on the acetamiprid concentration by using electrochromic material. The IrO2/ITO electrochromic film demonstrated magnificent cycle stability (100 cycles), high coloration efficiency (400 cm2 C-1 at 450 nm), and quick coloring/bleaching reaction time (8.60s/7.10s, respectively). By using in-situ spectroelectrochemical measurements, these optical properties of MIP/IrO2/ITO were obtained at various acetamiprid concentrations for quantitative analysis. By using differential pulse voltammetry between -0.2 V and +0.8 V (versus Ag/AgCl in 0.1 M PBS), the sensor performance of MIP/IrO2/ITO was assessed. In an acetamiprid concentration range of 4.29–38.6 nM, the MIP/IrO2/ITO electrode demonstrated linear response with a detection limit of 2.72 nM, sensitivity of 47.2 µA nM-1, and repeatability of 0.87%. Keywords: Electrochromism; Molecularly imprinted polymer (MIP); Pyrrole; IrO2;Acetamiprid; Electrochemical sensor; Spectroelectrochemistry. Acknowledgements This work was supported by The Scientific and Technological Research Council of Türkiye, TUBITAK (Project No:121Z784) as the financial.

Molecularly imprinted polymer (MIP)-based polymeric membrane potentiometric sensors have become an attractive tool for detection of organic species. However, the MIP receptors in potentiometric sensors developed so far are usually prepared by only using single functional monomers. This may lead to low affinities of the MIP receptors due to the lack of diversity of the functional groups, thus resulting in low detection sensitivity of the potentiometric sensors. Additionally, these classical MIP receptors are nonconductive polymers, which are undesirable for the fabrication of an electrochemical sensor. Herein, we describe a novel multifunctional MIP receptor-based potentiometric sensor. The multifunctional MIP receptor is prepared by using two functional monomers, methacrylic acid, and 3-vinylaniline with a dual functionality of both recognition and conduction properties. The poly(aniline) groups are introduced into the methacrylic acid-based MIP by postoxidation of the aniline monomer. Such poly(aniline) groups not only serve as the additional functional groups for selective recognition, but also work as a conducting polymer. The obtained multifunctional MIP receptor shows a high binding capacity and an excellent electron-transfer ability. By using bisphenol A as a model, the proposed multifunctional MIP sensor exhibits a largely improved sensitivity and low noise levels compared to the conventional MIP sensor. We believe that the proposed MIP-based sensing strategy provides a general and facile way to fabricate sensitive and selective MIP-based electrochemical sensors.

Improvement of the selectivity of a molecularly imprinted polymer-based potentiometric sensor by using a specific functional monomer