Molecularly Imprinted Polymer Sensor Research Articles

Raman spectroscopy‐based molecularly imprinted polymer sensor for sensitive detection of lysophosphatidic acid in serum

AbstractLysophosphatidic acid (LPA) has significant potential as a biomarker for diagnosis of ovarian cancer in female patients because it is present throughout all phases of the illness. Regrettably, there is not a clinically useful test for this biomarker yet. In this work, an ultra‐detection of LPA molecule by Raman spectroscopy‐based molecularly imprinted polymer (MIP) in serum samples is reported. β‐CD was synthesized to facilitate the collection of Raman spectroscopy and combined with MIP to denote it as β‐CD‐MIP for the adsorption of LPA with high sensitivity and selectivity. Linear regression model in serum samples shows peaks at 1100 and 1116 cm−1, respectively. A satisfactory linear fit was seen with LPA concentration log I = 3.7 log C + 1255.74 and with spiked serum log I = 4.6 log C + 327.22, respectively. The literature survey suggests the threshold LPA level in healthy person is 1.50 μM/L whereas the LPA level rises in patients with benign ovarian cancer tumor as 7.90 μM/L. This LPA level rises to 16.99 μM/L in ovarian cancer patients. On the basis of the band intensity, the limit of detection of the β‐CD‐MIP sensor for LPA was recorded as 0.003 μM/L. The binding constant of β‐CD‐MIP for LPA in serum was 0.031–0.003 μM/L, respectively. β‐CD‐MIP gel was optimized, characterized, and successfully applied on spiked serum samples. The findings of this research show that this substrate has a lot of potential for ultradetection of trace amounts of LPA molecule from the serum samples. The MIP sensor is robust, recyclable, efficient, and selective.

Emerging trends in functional molecularly imprinted polymers for electrochemical detection of biomarkers

Molecularly imprinted polymers (MIPs), functioning as artificial bioreceptors, hold significant promise for biomarker detection in healthcare, disease diagnosis, and addressing drug abuse. In contrast to natural bioreceptors, MIP-based sensors offer numerous advantages, such as high stability, cost-effectiveness, high selectivity, sensitivity, and notably straightforward preparation with customizable binding sites for diverse targets. Conventional MIP sensors often necessitate external redox reagents in analytes to transduce binding events into electrochemical signals for indirect detection, presenting challenges for practical applications in wearables or point-of-care (POC) testing. Redox-active MIP sensors have emerged as a viable alternative, enabling direct and label-free electrochemical detection, with two types developed. The first type utilizes electrocatalytic materials to expedite electron transfer and facilitate a redox reaction between the captured electroactive target and the electrode. The second type incorporates an embedded redox reactive component that allows selective binding of a target to modulate its electron transfer, leading to a change in the electrical signal. This review covers emerging trends and challenges in redox-active MIP sensors for direct electrochemical detection of biomarkers, focusing on sensing mechanisms, synthesis methods, and applications. Additionally, recent progress in wearable and POC redox-active MIP sensors is highlighted. A comprehensive outlook of challenges is further provided, aiming to advance direct biomarker detection for diverse healthcare applications.

Flexible Dual‐Channel Molecularly Imprinted Electrochemical Sensor for Simultaneously Monitoring Sweat Cortisol and Lactate Levels

While exercise offers significant potential to enhance overall well‐being, unscientific exercise practices often cause exercise fatigue, posing a threat to human health. Flexible sweat sensors have garnered considerable attention owing to their ability to continuously, non‐invasively, and dynamically monitor human health during exercise at the molecular level. Therefore, in this study, we constructed a flexible molecularly imprinted polymer (MIP) sensor for the real‐time monitoring of cortisol and lactate levels in sweat using cortisol or lactate as template molecules and pyrrole (Py) as functional monomer. Prussian blue (PB) was embedded into the MIP as a built‐in redox probe, eliminating the need for an additional probe and facilitating the simultaneous quantification of cortisol and lactate concentrations. Moreover, the MIP‐doped platinum nanoparticles (PtNPs) ehanced the electron transfer capability, further improving the sensitivity of the sensors. The fabricated flexibile cortisol and lactate MIP sensors demonstrated low limits of detection (LOD; 1.07 nM and 1.09 mM, respectively), high sensitivity (0.09 μA lg[nM]‐1 and 1.28 μA lg[nM]‐1), and exceptional stability and selectivity. The flexible MIP sensors could continuously and dynamically monitor changes in sweat cortisol and lactate concentrations, thus contributing to the advancement of next‐generation flexible sweat electrochemical sensors and providing a crucial tool for monitoring exercise fatigue.

Facile green synthesis of silver nanoparticles: Relevance in localized surface plasmon resonance and molecular imprinted polymer sensor for detection of Tetrabromobisphenol A in electronic waste

The present study demonstrates evocatively the interest in prioritizing an environmental friendly approach. Green synthesis of metallic nano-particles is carried out, which is further incorporated with a technique known as Molecular Imprinted Polymers (MIP) to develop a highly sensitive cuvette-based localized surface plasmon resonance (LSPR) probe for the selective detection of a Tetrabromobisphenol-A (TBBPA). TBBPA is a hazardous phenolic compound, mostly found in electronic waste (E-waste), that is abundant on earth. We have fabricated an LSPR probe with the help of a transparent glass substrate. A layer of Silver nanoparticles has been decorated over the glass substrate which further has an MIP overlayer on it. The glass slide dimensions are so chosen that it can fit inside the cuvette along its one side. The absorbance spectra are then recorded for a concentration range of 0–500 ng/ml of TBBPA. The sensitivity and limit of detection of the proposed sensor have been found to be 0.228 nm/ng ml−1 and 4.68 ng/ml respectively. Also, the probe showed quite promising recovery percentage greater than 85 % in real samples. Hence, with the findings and outcomes our fabricated probe can be represented as a potential candidate in selective detection of TBBPA along with the benefits of low cost of fabrication, portable, and real-time monitoring.

Nicotine detection in tobacco samples via a molecularly imprinted polymers sensing platform

A highly sensitive and selective molecularly imprinted polymer (MIP) sensing platform was developed for the detection of nicotine in tobacco samples. The MIP sensor was fabricated by integrating a PtNPs/GO nanocomposite with an electropolymerized nicotine-imprinted film on a glassy carbon electrode. Under optimal conditions (pH 7.4, 50 mM pyrrole, and 30 min elution time), the MIP sensor exhibited a wide linear range (0.01–0.5 μM and 0.5–100 μM), low detection limit (0.015 μM), good reproducibility (RSD < 4.2 %), and long-term stability (93.2 % retention after 30 days). The MIP sensor demonstrated excellent selectivity towards nicotine, with selectivity coefficients ranging from 7.2 to 9.5 against interfering substances. The practical applicability of the MIP sensor was validated by analyzing nicotine content in cigarettes and chewing tobacco samples, with recoveries ranging from 97.5 % to 102.8 % and relative errors within ±5 % compared to the reference GC-MS method. The proposed MIP-based electrochemical sensing platform offers a rapid, simple, and cost-effective approach for sensitive and selective detection of nicotine in complex tobacco matrices, showing great potential for applications in the tobacco industry and public health sector.

Development of Paper-Based Fluorescent Molecularly Imprinted Polymer Sensor for Rapid Detection of Lumpy Skin Disease Virus.

Lumpy Skin Disease (LSD) is a notifiable viral disease caused by Lumpy Skin Disease virus (LSDV). It is usually associated with high economic losses, including a loss of productivity, infertility, and death. LSDV shares genetic and antigenic similarities with Sheep pox virus (SPV) and Goat pox (GPV) virus. Hence, the LSDV traditional diagnostic tools faced many limitations regarding sensitivity, specificity, and cross-reactivity. Herein, we fabricated a paper-based turn-on fluorescent Molecularly Imprinted Polymer (MIP) sensor for the rapid detection of LSDV. The LSDV-MIPs sensor showed strong fluorescent intensity signal enhancement in response to the presence of the virus within minutes. Our sensor showed a limit of detection of 101 log10 TCID50/mL. Moreover, it showed significantly higher specificity to LSDV relative to other viruses, especially SPV. To our knowledge, this is the first record of a paper-based rapid detection test for LSDV depending on fluorescent turn-on behavior.

Environmentally friendly anti-biofouling polymeric membrane potentiometric sensors based on imprinted receptors

Polymeric membrane potentiometric sensors using molecularly imprinted polymer (MIP) receptors are an ideal tool for determination of organic ionic species. However, their applications in complicated samples are very limited because of occurrence of sensor biofouling. Herein, for the first time, we describe a simple but environmentally friendly strategy to improve anti-biofouling performance of MIP-based potentiometric sensors. The non-toxic, environmentally friendly anti-fouling agent is doped into the polymeric membrane. The released organic biocidal agent from the polymeric membrane can kill the microorganisms adhered to the sensing membrane surface, and the formation of biofilms can thus be prevented. As a proof-the-concept experiment, an all-solid-state MIP-based potentiometric ceftiofur sensor is selected as a model. Capsaicin, a naturally occurring alkaloid derived from chillis, is chosen as a non-toxic biocide agent. Another widely used biocide agent 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) with low toxicity is also used as a comparison. Compared to the undoped electrode, the capsaicin-doped MIP sensor exhibits remarkably improved anti-biofouling abilities in terms of the low survival rates and the low adhesion rates of the bacterial cells and microalgae. Especially, the capsaicin-based electrode displays similar anti-fouling and response properties to the DCOIT-based one. It can be anticipated that such anti-fouling strategy may lay the foundation for development of “green” anti-fouling sensors, which are urgently required in marine monitoring and clinical diagnosis.

Molecularly imprinted orthophenylenediamine with Ti3C2TxMXene‐based biosensor for sensitive detection of bilirubin

AbstractIn this study, bilirubin (BR) is detected by using a novel molecularly imprinted electrochemical sensor based on a Ti3C2TxMXene‐modified ITO electrode. First, Ti3C2TxMXene is synthesized by chemical etching and deposited at the ITO electrode surface by drop casting. After that, ortho‐phenylenediamine (o‐PD) as monomer is electropolymerized in the presence of a sodium acetate buffer solution containing the BR template to prepare BR‐imprinted electrode. Field emission scanning electron microscopy (FESEM), x‐ray diffraction and UV–visible absorption spectroscopy confirms the MXene synthesis. The molecular imprinted polymer (MIP) formation at the electrode is confirmed by electrochemical methods such as differential pulse voltammetry, electrochemical impedance spectroscopy, and cyclic voltammetry, and FESEM. The linearity range, limit of detection and the limit of quantification are calculated as 0.1 mg/dL to 20 mg/dL, 0.002 mg/dL, and 6.6 mg/dL respectively. Stability and reproducibility are also reported for the prepared MIP sensor.

Glyphosate detection via a nanomaterial-enhanced electrochemical molecularly imprinted polymer sensor

Glyphosate (GLY) is a widely used herbicide with an important role in agriculture. It effectively controls weeds, enhancing agricultural yield and product quality. However, its use raises significant concerns such as potential risks to non-target ecosystems and human health. In response to these concerns, we develop an electrochemical sensor with a molecularly imprinted polymer (MIP) and gold nanoparticles for GLY detection. The sensor includes a screen-printed carbon electrode (SPCE) functionalized with gold nanoparticles and a self-assembled polyvinyl carboxylic acid chloride (PVC-COOH) layer. GLY compounds interact with carboxylic groups and are encapsulated by a polymer of methacrylic acid (MAA) cross-linked with ethylene glycol dimethacrylate (EGDMA). Electrochemical performance was assessed using differential pulse voltammetry (DPV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Morphological characterization was performed using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM). The sensor exhibits impressive selectivity, detecting GLY within a range of 273–1200 pg/mL with minimal interference from other pesticides. It boasts a low detection limit of 0.8 pg/mL (signal-to-noise ratio S/N = 3) by DPV and 0.001 pg/mL by EIS. The sensor’s versatility extends to various sample types, including surface water, agricultural wastewater, soil, and cucumber, demonstrating high recovery rates (> 96.05%) and low relative standard deviation (RSD) (< 5.7%). The developed MIP sensor is proven to be a valuable tool for rapid and highly sensitive detection of GLY in diverse environmental and agri-food samples.

Electrochemically Synthesized MIP Sensors: Applications in Healthcare Diagnostics.

Early-stage detection and diagnosis of diseases is essential to the prompt commencement of treatment regimens, curbing the spread of the disease, and improving human health. Thus, the accurate detection of disease biomarkers through the development of robust, sensitive, and selective diagnostic tools has remained cutting-edge scientific research for decades. Due to their merits of being selective, stable, simple, and having a low preparation cost, molecularly imprinted polymers (MIPs) are increasingly becoming artificial substitutes for natural receptors in the design of state-of-the-art sensing devices. While there are different MIP preparation approaches, electrochemical synthesis presents a unique and outstanding method for chemical sensing applications, allowing the direct formation of the polymer on the transducer as well as simplicity in tuning the film properties, thus accelerating the trend in the design of commercial MIP-based sensors. This review evaluates recent achievements in the applications of electrosynthesized MIP sensors for clinical analysis of disease biomarkers, identifying major trends and highlighting interesting perspectives on the realization of commercial MIP-endowed testing devices for rapid determination of prevailing diseases.

The Effect of Polymerization Techniques on the Creation of Molecularly Imprinted Polymer Sensors and Their Application on Pharmaceutical Compounds.

Molecularly imprinted polymers (MIPs) have become more prevalent in fabricating sensor applications, particularly in medicine, pharmaceuticals, food quality monitoring, and the environment. The ease of their preparation, adaptability of templates, superior affinity and specificity, improved stability, and the possibility for downsizing are only a few benefits of these sensors. Moreover, from a medical perspective, monitoring therapeutic medications and determining pharmaceutical compounds in their pharmaceutical forms and biological systems is very important. Additionally, because medications are hazardous to the environment, effective, quick, and affordable determination in the surrounding environment is of major importance. Concerning a variety of performance criteria, including sensitivity, specificity, low detection limits, and affordability, MIP sensors outperform other published technologies for analyzing pharmaceutical drugs. MIP sensors have, therefore, been widely used as one of the most crucial techniques for analyzing pharmaceuticals. The first part of this review provides a detailed explanation of the many polymerization techniques that were employed to create high-performing MIP sensors. In the subsequent section of the review, the utilization of MIP-based sensors for quantifying the drugs in their pharmaceutical preparation, biological specimens, and environmental samples are covered in depth. Finally, a critical evaluation of the potential future research paths for MIP-based sensors clarifies the use of MIP in pharmaceutical fields.

Performance Test of the Molecularly Imprinted Polymer (MIP) Endosulfan Sensor Potentiometrically

Molecularly Imprinted Polymer (MIP) is a synthetic polymer with cavities that are specific for target molecules. Cavities are obtained as a result of template removal, where the function of these cavities is to recognize molecules with the same size, structure and physicochemical properties as them. The polymer produced from the MIP technique is applied to the surface of the sensor material as an endosulfan detection and analyzing instrument. The advantage of MIP is that it is a sensor system that is able to provide analysis results for contamination quickly, easily and in low concentrations (ppm). The aim of this research is to make MIP endosulfan as a contamination sensor and potentiometrically test its performance. The research results showed that the optimum conditions for making Molecularly Imprinted Polymer (MIP) endosulfan were obtained with a composition of 6.02 mL of chloroform; endosulfan 0.025 g; 0.9 mL methacrylic acid (MAA); 1.57 mL ethylene glycol methacrylic acid (EGMA); 0.07 g benzoyl peroxide (BPO) with a heating time of 150 minutes at a temperature of 70 oC. The sensor performance test was carried out potentiometrically and it was found that the endosulfan MIP sensor had sensitivity and stability in the concentration range of 0.01-1.0x10-6 ppm with a detection limit of 0.01x10-6 ppm and a service life of 90 days.

Spectrum-resolved photoelectrochemical molecularly imprinted sensors for simultaneous determination of ascorbic acid and uric acid in a differential mode

Herein, a spectrum-resolved differential strategy was proposed to enhance further the selectivity of photoelectrochemical (PEC) sensors, demonstrated by the simultaneous determinations of ascorbic acid (AA) and uric acid (UA). Molecularly imprinted polymer (MIP) membranes for AA (MIPAA) and UA (MIPUA) were fabricated on the surface of TiO2 nanotubes via electropolymerization, using pyrrole as functional monomer, AA and UA as templates, respectively. It was shown that the increase in absorbance from AA or UA within the MIP membranes resulted in an intense decrease in the photocurrent of the PEC sensors. In the spectrum-resolved differential mode, ΔRIAA= (IAA/IAA0−IUA/IUA0)310 and ΔRIUA= (IUA0/IUA −IAA0/IAA)275 were used in the simultaneous determinations of AA and UA, respectively. Where IAA, IAA0, IUA and IUA0 are the photocurrents of MIPAA and MIPUA in sample and blank, the subscripts of 275 and 310 stand for the excitation wavelength (nm), respectively. The interference levels in the differential mode were reduced by one order of magnitude compared with the normal MIP mode. The spectrum-resolved differential PEC MIP sensors were used in the simultaneous determination of AA and UA in serum and urine samples, with the detection limits of 0.019 and 0.036 μM, respectively.

Sensitive Recognition of Acetamiprid with a Unique Electrochromic Molecular Imprinted Polymer Sensor

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.

Optimisation of electrochemical sensors based on molecularly imprinted polymers: from OFAT to machine learning.

Molecularly imprinted polymers (MIPs) rely on synthetic engineered materials able to selectively bind and intimately recognise a target molecule through its size and functionalities. The way in which MIPs interact with their targets, and the magnitude of this interaction, is closely linked to the chemical properties derived during the polymerisation stages, which tailor them to their specific target. Hence, MIPs are in-deep studied in terms of their sensitivity and cross-reactivity, further being used for monitoring purposes of analytes in complex analytical samples. As MIPs are involved in sensor development within different approaches, a systematic optimisation and rational data-driven sensing is fundamental to obtaining a best-performant MIP sensor. In addition, the closer integration of MIPs in sensor development requires that the inner properties of the materials in terms of sensitivity and selectivity are maintained in the presence of competitive molecules, which focus is currently opened. Identifying computational models capable of predicting and reporting the best-performant configuration of electrochemical sensors based on MIPs is of immense importance. The application of chemometrics using design of experiments (DoE) is nowadays increasingly adopted during optimisation problems, which largely reduce the number of experimental trials. These approaches, together with the emergent machine learning (ML) tool in sensor data processing, represent the future trend in design and management of point-of-care configurations based on MIP sensing. This review provides an overview on the recent application of chemometrics tools in optimisation problems during development and analytical assessment of electrochemical sensors based on MIP receptors. A comprehensive discussion is first presented to cover the recent advancements on response surface methodologies (RSM) in optimisation studies of MIPs design. Therefore, the recent advent of machine learning in sensor data processing will be focused on MIPs development and analytical detection in sensors.

Single-monomer dual templated MIP based electrochemical sensor for tartrazine and brilliant blue FCF

In this study, a dual-templated molecularly imprinted polymer-based electrochemical sensor was developed for the simultaneous analysis of two food additive dyes, brilliant blue FCF and tartrazine. Using a 3-aminophenyl boronic acid (3-APBA) monomer and the dual templates of brilliant blue FCF (BB) and tartrazine (TZ), the molecularly imprinted polymer (MIP) layer was electropolymerized on the carbon fibre paper (CFP) electrode. By using BB and TZ as template molecules along the electro-polymerization of 3-APBA, then removing both template molecules, the MIP film was generated on the surface of the CFP electrode. Due to the high surface area provided by modification, several complementary binding sites for template molecules are formed on the surface of the MIP sensor during this process of sensor fabrication. On the MIP/CFP electrode, the electrochemical behavior of BB and TZ was assessed. The monomer/template ratio, pH values, and influencing parameters like the electro-polymerization scanning cycles were all optimized. This sensor was applied to detect brilliant blue FCF and tartrazine in beverage and food samples using MIPAPBA/CFP electrode.

A highly sensitive and selective hybrid of molecularly imprinted poly(9H-carbazole-9-ethanamine) and porous CoZn-NC polyhedral nanocages for electrochemical detection of uric acid in plasma sample

A novel monomer, 9H-carbazole-9-ethanamine, was prepared in this study to prepare a molecularly imprinted polymer (MIP) on porous Co/Zn embedded N-doped carbon (CoZn-NC) material for the purpose of detecting uric acid (UA). The electro-polymerization of the carbazole derivatives obtained by introducing an amino group onto the rigid structure of the carbazole conjugate led to the creation of a polymer with a significant number of amino groups. This increased the number of binding sites available for the UA template and enhanced the selectivity of the sensor. Additionally, porous CoZn-NC polyhedral nanocages were used as the substrate material for the MIP sensor, which enhanced the sensing performance through a highly conductive sensing interface and an efficient UA catalytic capacity. The preparation conditions for the MIP@CoZn-NC were optimized to achieve high sensitivity in the detection of UA using differential pulse voltammetry (DPV). The detection range of UA is 1 to 300 μM using this method, and it exhibits good selectivity for compounds with similar structures. The developed sensor was successfully used to detect UA in rat plasma, with a recovery rate of 91.8% to 103.7%, demonstrating its potential for biomedical applications.

Electrochromic molecular imprinted polymer sensor for detection of selective acetamiprid

An electrochromic molecular imprinted polymer sensor was constructed by electropolymerization of IrO2 as an electrochromic material on an indium tin oxide glass substrate and electrosynthesis on this electrode was achieved with pyrrole as a functional monomer in the presence of acetamiprid as a template. With the designed electrochromic MIP sensor, it was aimed to detect the color change of the electrochromic material with change in the acetamiprid concentration by the naked eye and to develop a selective pesticide sensor by molecular imprinted polymer technology. These optical characteristics of MIP/IrO2/ITO were determined with different acetamiprid concentrations for quantitative analysis by in-situ spectroelectrochemical measurements. The sensor performance of MIP/IrO2/ITO was determined with differential pulse voltammetry between −0.2 V and + 0.8 V (vs Ag/AgCl in 0.1 M phosphate buffer solution. MIP/IrO2/ITO electrode exhibited linear response with acetamiprid concentrations in the range of 4.29–38.6 nM with a detection limit of 2.72 nM, sensitivity of 47.2 μA nM−1 and reproducibility of 0.87 %.

Investigations on the electrochemical behavior of sunitinib and metabolites N-desethyl-sunitinib and sunitinib-N-oxide and its selective determination using molecularly imprinted polymer-based sensor

Sunitinib (SUN) is an orally administered tyrosine kinase inhibitor and is mainly metabolized via N-deethylation to form the primary active metabolite N-desethyl-sunitinib (M1) and via oxidation to sunitinib-N-oxide (M2). In this study, we first investigated the electrochemical behavior of sunitinib and its N-desethyl and N-oxide metabolites on a bare glassy carbon electrode (GCE) by cyclic voltammetry (CV) technique. Based on the results, a plausible electrooxidation mechanism is proposed, yielding the oxo-desfluoro-sunitinib (quinoneimine metabolite) via oxidative defluorination of sunitinib. After this phase of the study, due to the low sensitivity and selectivity results obtained from the bare GCE, we aimed to develop the first molecularly imprinted polymer (MIP)-based electrochemical sensor for the sensitive and selective determination of SUN. The MA@SDS/MIP-GCE sensor was prepared by thermal polymerization of methacrylic acid (MA) as a functional monomer in the presence of SUN on a GCE surface under the optimized parameters such as template/monomer ratio, drop amount, polymerization temperature and time, removal solution and time, and rebinding time, which affect the structure and response of the sensor. The surface characterization of the developed sensor was performed by scanning electron microscopy (SEM), and the electrochemical characterization was performed by CV and electrochemical impedance spectroscopy (EIS). The electroanalytical performance of the MA@SDS/MIP-GCE sensor was tested by differential pulse voltammetry (DPV) under the optimized conditions in comparison with the NIP-based sensor. The linearity of the developed sensor for the determination of SUN was investigated in the concentration range of 0.5 – 5.0 nM for standard and serum solutions with low LOD and LOQ values. The application of the MIP sensor for the determination of SUN in pharmaceutical dosage form (capsule) and serum samples was demonstrated with excellent recoveries. The results showed that the MA@SDS/MIP-GCE sensor is a sensitive, specific, selective, rapid, and economical option for the quantitative determination of SUN.

Highly stable electrochemical sensing platform for the selective determination of pefloxacin in food samples based on a molecularly imprinted-polymer-coated gold nanoparticle/black phosphorus nanocomposite

The overuse of pefloxacin (PEF) leaves residues in foods. Therefore, the development of robust analytical techniques for the selective detection of PEF is of great importance. In this study, a highly stable electrochemical sensing platform has been constructed, using molecularly imprinted polymer (MIP)-coated gold nanoparticle/black phosphorus nanocomposites (BPNS-AuNPs), for the selective detection of PEF. BPNS-AuNPs significantly enhance the black phosphorus (BP) stability and electrochemical activity and offer a larger surface area to accommodate more imprinted sites for selective PEF binding. MIP/BPNS-AuNPs exhibit a broad linear detection range (0.005–10 μM), low detection limit (0.80 nM), and high sensitivity (3.199 μA μM−1). The MIP/BPNS-AuNPs show a high binding affinity for PEF, even in the presence of structural analogs, and maintain stable voltammetric signals for at least 35 d. The MIP sensor exhibits consistent high sensitivity in the detection of PEF in real milk and orange juice samples.