Trace anthracene electrochemical detection based on electropolymerized-molecularly imprinted polypyrrole modified glassy carbon electrode

A novel Bi2S3 QD-based DPV/ECL synchronous dual-mode molecularly imprinted sensor for enrofloxacin detection in eggs

Herein, a novel electrochemiluminescence (ECL) and differential pulse voltammetry (DPV) dual-mode-based molecularly imprinted (MIP) sensor had been established for the detection of enrofloxacin (ENR) in eggs. Firstly, bismuth sulfide quantum dots (Bi2S3 QDs) as ECL luminophore were synthesized. Furthermore, a MIP film with ionic liquid (ILs), Bi2S3 QDs, and ENR was prepared via the electrochemical polymerization procedure on the electrode. As ENR was identified and captured by the imprinted cavities, the electron transfer pathway was blocked on the electrochemical interface, resulting in the decrease of both DPV signals and ECL signals. As a novel synchronous dual-mode sensing strategy, a pulsed voltage was applied to produce both the DPV signal and ECL signal simultaneously. The ECL and DPV response showed the good linear relationships with the concentration of ENR with the ranges of 0.5 Nm-25 μM and 5 nM-25 μΜ and the detection limits of 0.13 nM and 1.59 nM, respectively.

A novel electropolymerized molecularly imprinted dual-mode sensor for bisphenol AF detection in pond mud

Recently, bisphenol AF (BPAF) as most commonly used bisphenol A analogs had the increasing higher level in the environment with unknown risks. Herein, a synchronous dual-mode sensor had been established based on differential pulse voltammetry (DPV) and electrochemiluminescence (ECL) for the detection of BPAF in pond mud. Firstly, the sensing molecularly imprinted polymer (MIP) films were prepared by electrochemical polymerization procedure with 3,4-ethoxylene dioxy thiophene (EDOT) as the functional monomer, BPAF as the template molecule and MXene as the supporting electrolyte. Due to unique characters of PEDOT and MXene, the constructed MIP films were stable and highly conductive. Meanwhile, zinc-doped bismuth sulfide quantum dots (Zn-Bi2S3 QDs) were synthesized as a nano-emitter to generate strong ECL signals in the MIP film. In the sensing process, a pulsed voltage applied to the PEDOT/MXene MIP film to generate both DPV and ECL signals for simultaneous dual-mode detection. Additionally, the liquid-liquid extraction with deep eutectic solvent (menthol: octanol 1:1) was used for the pre-concentration of the BPAF in the pond mud. Based on the sensing system, the ECL and DPV response showed the good linear relationships with the concentration of BPAF with the ranges of 0.01 μM-50 μM and 0.1 μM-50 μM and the detection limits of 0.0060 μM and 0.059 μM, respectively.

An ultra-sensitive and selective electrochemical sensor based on GOCS composite and ion imprinted polymer for the rapid detection of Cd2+ in food samples

An ultra-sensitive and selective electrochemical sensor was proposed through the combination of carbon disulfide-functionalized graphene oxide (GOCS) composite with high conductivity and cadmium ion-imprinted polymer (IIP). Using pyrrole as the functional monomer and Cd²⁺ as the template ion, the IIP was formed by in situ electropolymerization on GOCS composite. Under the optimized experimental conditions, the sensor exhibited a good linear relationship in the range of 0.5-50 μg/L Cd²⁺ concentration, with the lowest detection limit of 0.23 μg/L. The sensor exhibited not only good selectivity for the determination of Cd²⁺, but also good repeatability with current response remaining 87.6 % after four cycles. Furthermore, the sensor exhibited similar sensing performance in lettuce, orange and peach with recovery ranging from 82.6 % to 110.63 %. This work is expected to provide an electrochemical sensor with excellent selectivity, good stability and sensitivity for the detection of trace amounts of Cd²⁺ in real samples.

Molecularly Imprinted Polymer-Based Sensor for Electrochemical Detection of Cortisol

As a steroid hormone, cortisol has a close relationship with the stress response, and therefore, can be used as a biomarker for early detection of stress. An electrochemical immunosensor is one of the most widely used methods to detect cortisol, with antibodies as its bioreceptor. Apart from conventional laboratory-based methods, the trend for cortisol detection has seemed to be exploiting antibodies and aptamers. Both can provide satisfactory performance with high selectivity and sensitivity, but they still face issues with their short shelf life. Molecularly imprinted polymers (MIPs) have been widely used to detect macro- and micro-molecules by forming artificial antibodies as bioreceptors. MIPs are an alternative to natural antibodies, which despite demonstrating high selectivity and a low degree of cross-reactivity, often also show a high sensitivity to the environment, leading to their denaturation. MIPs can be prepared with convenient and relatively affordable fabrication processes. They also have high durability in ambient conditions, a long shelf life, and the ability to detect cortisol molecules at a concentration as low as 2 ag/mL. By collecting data from the past five years, this review summarizes the antibody and aptamer-based amperometric sensors as well as the latest developments exploiting MIPs rather than antibodies. Lastly, factors that can improve MIPs performance and are expected to be developed in the future are also explained.

Metal-Organic Frameworks Meet Molecularly Imprinted Polymers: Insights and Prospects for Sensor Applications

The use of porous materials as the core for synthesizing molecularly imprinted polymers (MIPs) adds significant value to the resulting sensing system. This review covers in detail the current progress and achievements regarding the synergistic combination of MIPs and porous materials, namely metal/covalent-organic frameworks (MOFs/COFs), including the application of such frameworks in the development of upgraded sensor platforms. The different processes involved in the synthesis of MOF/COF-MIPs are outlined, along with their intrinsic properties. Special attention is paid to debriefing the impact of the morphological changes that occur through the synergistic combination compared to those that occur due to the individual entities. Thereafter, the strategies used for building the sensors, as well as the transduction modes, are overviewed and discussed. This is followed by a full description of research advances for various types of MOF/COF-MIP-based (bio)sensors and their applications in the fields of environmental monitoring, food safety, and pharmaceutical analysis. Finally, the challenges/drawbacks, as well as the prospects of this research field, are discussed in detail.

Determination of 5-hydroxymethylfurfural using an electropolymerized molecularly imprinted polymer in combination with Salle

Coffee, a beverage with a complex chemical composition, is appreciated for the sensory experience of its taste and aroma. The compound 5-(hydroxymethyl)-2-furfural (HMF) is essential for sensory characterization of the beverage, and is also used in the traceability of its production. In this work, a procedure combining salting-out assisted liquid-liquid extraction (SALLE) and an electropolymerized molecularly imprinted polymer (e-MIP) was developed for the detection and quantification of HMF in coffee samples. The sample preparation step using SALLE employed a combination of acetonitrile and phosphate-buffered saline, in a proportion of 70:30 (ACN:PBS), with addition of 0.02 g of NaCl. The new sensor (e-MIP) was prepared by electropolymerization of p-aminobenzoic acid onto a glassy carbon electrode (GCE) using cyclic voltammetry (CV). Analytical determinations were performed by differential pulse voltammetry (DPV). The linear regression correlation coefficient (r²) for the response was 0.9986. The limits of detection and quantification were 0.372 mg L^-1 and 1.240 mg L^-1, respectively. The repeatability and reproducibility values obtained were 6 and 10%, respectively. The recoveries for three concentration levels were between 97 and 101%. Analyses of different coffee samples showed that the HMF concentrations varied from 261.0 ± 41.0 to 770.2 ± 55.9 mg kg^-1 in powdered coffee samples, and from 1510 ± 50 to 4445 ± 278 mg kg^-1 in instant coffee samples. The advantages of this procedure, compared to other methods described in the literature, are its simplicity, easy operation, good selectivity and sensitivity, low cost, and minimal use of organic solvents.

Modern and Dedicated Methods for Producing Molecularly Imprinted Polymer Layers in Sensing Applications

Molecular imprinting (MI) is the most available and known method to produce artificial recognition sites, similar to antibodies, inside or at the surface of a polymeric material. For this reason, scholars all over the world have found MI appealing, thus developing, in this past period, various types of molecularly imprinted polymers (MIPs) that can be applied to a wide range of applications, including catalysis, separation sciences and monitoring/diagnostic devices for chemicals, biochemicals and pharmaceuticals. For instance, the advantages brought by the use of MIPs in the sensing and analytics field refer to higher selectivity, sensitivity and low detection limits, but also to higher chemical and thermal stability as well as reusability. In light of recent literature findings, this review presents both modern and dedicated methods applied to produce MIP layers that can be integrated with existent detection systems. In this respect, the following MI methods to produce sensing layers are presented and discussed: surface polymerization, electropolymerization, sol–gel derived techniques, phase inversionand deposition of electroactive pastes/inks that include MIP particles.

Novel electrochemical sensor modified with molecularly imprinted polymers for determination of enrofloxacin in marine environment

Molecularly imprinted polymers were synthesized by gel-sol method with multi-walled carbon nanotubes as support and enrofloxacin as a template and further modified on the surface of glassy carbon electrode to construct a molecularly imprinted electrochemical sensor. The performance of the imprinted electrochemical sensor was thoroughly investigated by using cyclic voltammetry and differential pulse voltammetry. The influence of imprinted polymers amount, electrolyte pH, and incubation time on the sensor performance was investigated for the detection of enrofloxacin. Under the optimal experimental conditions in a three-electrode system with the modified electrode as the working electrode the differential pulse voltammetry response current of the sensor had a good linear relationship at 0.2 V (vs. saturated calomel reference electrode) with the enrofloxacin concentration within 2.8 pM-28 μM and the limit of detection of the method was 0.9 pM. The competitive interference experiment showed that the imprinted electrochemical sensor could selectively recognize enrofloxacin. The method was applied to analyze spiked natural seawater, fish, and shrimp samples. The recovery was 96.4%-102%, and RSD was less than 4.3% (n = 3), indicating that the proposed imprinted electrochemical sensor was suitable for the determination of trace enrofloxacin in marine environment samples.

Selective non-enzymatic uric acid sensing in the presence of dopamine: electropolymerized poly-pyrrole modified with a reduced graphene oxide/PEDOT:PSS composite

A molecularly imprinted polymer (MIP) with uric acid cavities increases the selectivity of uric acid measurement in the presence of dopamine as an interferent.

Molecularly imprinted polymers in toxicology: a literature survey for the last 5 years

The science of toxicology dates back almost to the beginning of human history. Toxic chemicals, which are encountered in different forms, are always among the chemicals that should be investigated in criminal field, environmental application, pharmaceutic, and even industry, where many researches have been carried out studies for years. Almost all of not only drugs but also industrial dyes have toxic side and direct effects. Environmental micropollutants accumulate in the tissues of all living things, especially plants, and show short- or long-term toxic symptoms. Chemicals in forensic science can be known by detecting the effect they cause to the body with the similar mechanism. It is clear that the best tracking tool among analysis methods is molecularly printed polymer-based analytical setups. Different polymeric combinations of molecularly imprinted polymers allow further study on detection or extraction using chromatographic and spectroscopic instruments. In particular, methods used in forensic medicine can detect trace amounts of poison or biological residues on the scene. Molecularly imprinted polymers are still in their infancy and have many variables that need to be developed. In this review, we summarized how molecular imprinted polymers and toxicology intersect and what has been done about molecular imprinted polymers in toxicology by looking at the studies conducted in the last 5 years.

Fast microwave-assisted synthesis of magnetic molecularly imprinted polymer for sulfamethoxazole

A fast and simple strategy based on the microwave technique for the preparation of magnetic molecularly imprinted polymers (MMIPs) is proposed for the selective determination of sulfamethoxazole (SMX). The MMIPs were synthesized at 70 °C in 20 min, being much faster than the conventional techniques. A computational approach based on density functional theory was used to design the MMIP and compare the two most used monomers in MIPs, including methacrylic acid (MAA) and acrylamide (AM). Then, two different MMIPs were prepared using AM and MAA as monomers. The resultant materials were characterized with X-ray diffraction, thermogravimetric analysis, scanning/transmission electron microscopy, and Fourier-transform infrared spectroscopy. Besides, the adsorption characterizations suggested that the adsorption of SMX followed the pseudo-second-order model in the kinetic study and the Sips model in the isotherm study. The experimental results corroborated the computational approach. Furthermore, Both MMIPs demonstrated good selectivity. The MMIP-AM and MMIP-MAA were applied as adsorbents in magnetic dispersive solid-phase extraction combined with UV-visible spectroscopy to quantify SMX. The obtained limits of detection and quantification were lower than 0.59 and 1.77 μM, respectively for both MMIPs. The sensitivity of both MMIPs was in the range of 0.021-0.023 (SI). Our findings revealed that there is no significant difference in the analytical parameters between MMIP-AM and MMIP-MAA. However, the application of both MMIPs in a real sample (tap water) showed that the recovery values of SMX obtained with MMIP-AM (68-70%) were lower than that with MMIP-MAA (80-90%) suggesting that MMIP-MAA is more appropriate for SMX determination.

Electropolymerised Polypyrroles as Active Layers for Molecularly Imprinted Sensors: Fabrication and Applications

Conjugated polymers are widely used in the development of sensors, but even though they are sensitive and robust, they typically show limited selectivity, being cross-sensitive to many substances. In turn, molecular imprinting is a method involving modification of the microstructure of the surface to incorporate cavities, whose shape matches that of the “template”—the analyte to be detected, resulting in high selectivity. The primary goal of this review is to report on and briefly explain the most relevant recent developments related to sensors utilising molecularly imprinted polypyrrole layers and their applications, particularly regarding the detection of bioactive substances. The key approaches to depositing such layers and the most relevant types of analytes are highlighted, and the various trends in the development of this type of sensors are explored.

Electroanalytical profiling of cocaine samples by means of an electropolymerized molecularly imprinted polymer using benzocaine as the template molecule

Cocaine samples were ‘finger-printed’ using e-MIPs, constructed on the surface of portable SPCEs. The SWV data with suitable chemometric analysis provides valuable information about the drugs’ provenience which is crucial to tackle drug traffic.