A critical review of molecularly imprinted polymers for the analysis of organic pollutants in environmental water samples

A new SERS quantitative analysis strategy for ultratrace chloramphenicol with Fe3O4@MIP nanocatalytic probe

Three functional magnetic nanocatalytic probe, which integrates recognition, catalytic amplification, and separation enrichment, is a new approach to construct a simple, fast, highly selective, and sensitive analytical method. In this article, a new magnetic nanosurface molecularly imprinted polymer nanoprobe (Fe3O4@MIP) with trifunctionality was rapidly prepared using a microwave-assisted method with magnetic Fe3O4 nanoparticles as a substrate, chloramphenicol (CAP) as a template molecule, and methacrylic acid as a functional monomer. The characterized nanoprobe was found that could specifically recognize CAP, strongly catalyze the new indicator nanoreaction of fructose (DF)-HAuCl4. The gold nanoparticles (AuNPs) exhibit strong resonance Rayleigh scattering (RRS) and surface enhanced Raman scattering (SERS) effects. Upon addition of CAP, the SERS/RRS signals were linearly weakened. Accordingly, a new SERS/RRS analysis platform for highly sensitive and selective determination of CAP was constructed. The SERS linear range was 0.0125-0.1 nmol/L, with detection limit (DL) of 0.004 nmol/L CAP. Furthermore, it could be combined with magnet-enriched separation to further improve the sensitivity, with a DL of 0.04 pmol/L CAP. The SERS method has been used for the determination of CAP in real samples, with relative standard deviations of 2.37-9.89 % and the recovery of 95.24-107.1 %.

Environmentally friendly molecularly imprinted polymers as an insert for SPE type columns in the gentamicin monitoring process

The quantity and variety of micro-pollutants infiltrating water resources have increased rapidly in recent times. The appearance of many harmful substances in the waters has resulted in so-called chemical cocktails which significantly contribute to the deterioration of water quality. Additionally, the variety of these compounds, often similar to each other in terms of molecular weights, makes their separation and identification very difficult. In this paper we present the possibility of using self-regenerating mechanism of molecularly imprinted polymers to measure the concentration of micropollutants in the aquatic environment. Molecularly imprinted polymers toward gentamicin were prepared by monomer polymerization in aqueous solution at ambient temperature. Results from computer-based molecular modelling demonstrated potential binding sites between gentamicin and functional monomers in water. Various compositions of polymerization mixtures were tested. The ratio of monomers to each other was 1.1:1.4:0.0015 and 1:1:1 for N-isopropylacrylamine:acrylamide:acrylic acid, respectively. For each composition, various amounts of the standard were tested: 0, 3, 5, 7, 10,15 mol% in relation to monomers. The best results were obtained for 5 % gentamicin with an excess of acrylamide in relation to the other monomers. Sorption for this system was 0.783 mg/g at ambient temperature and desorption 0.593 at 4 °C. The synthesized materials, thanks to the incorporation of thermosensitive poly(N-isopropylacrylamide) into their structures, were able to release 89 % of adsorbed gentamicin. This made it possible to use the designed SPE columns repeatably with similar efficiency. The prepared materials were selective in the presence of other antibiotics like amoxicillin and norfloxacin.

Developments and Applications of Molecularly Imprinted Polymer-Based In-Tube Solid Phase Microextraction Technique for Efficient Sample Preparation

Despite advancements in the sensitivity and performance of analytical instruments, sample preparation remains a bottleneck in the analytical process. Currently, solid-phase extraction is more widely used than traditional organic solvent extraction due to its ease of use and lower solvent requirements. Moreover, various microextraction techniques such as micro solid-phase extraction, dispersive micro solid-phase extraction, solid-phase microextraction, stir bar sorptive extraction, liquid-phase microextraction, and magnetic bead extraction have been developed to minimize sample size, reduce solvent usage, and enable automation. Among these, in-tube solid-phase microextraction (IT-SPME) using capillaries as extraction devices has gained attention as an advanced "green extraction technique" that combines miniaturization, on-line automation, and reduced solvent consumption. Capillary tubes in IT-SPME are categorized into configurations: inner-wall-coated, particle-packed, fiber-packed, and rod monolith, operating either in a draw/eject system or a flow-through system. Additionally, the developments of novel adsorbents such as monoliths, ionic liquids, restricted-access materials, molecularly imprinted polymers (MIPs), graphene, carbon nanotubes, inorganic nanoparticles, and organometallic frameworks have improved extraction efficiency and selectivity. MIPs, in particular, are stable, custom-made polymers with molecular recognition capabilities formed during synthesis, making them exceptional "smart adsorbents" for selective sample preparation. The MIP fabrication process involves three main stages: pre-arrangement for recognition capability, polymerization, and template removal. After forming the template-monomer complex, polymerization creates a polymer network where the template molecules are anchored, and the final step involves removing the template to produce an MIP with cavities complementary to the template molecules. This review is the first paper to focus on advanced MIP-based IT-SPME, which integrates the selectivity of MIPs into efficient IT-SPME, and summarizes its recent developments and applications.

Unveiling the potential of molecular imprinting polymer-based composites in the discovery of advanced drug delivery carriers

Molecularly imprinted polymers (MIPs) are polymeric matrices that can mimic natural recognition entities, such as antibodies and biological receptors. Molecular imprinting of therapeutics is very appealing in the design of drug delivery systems since the specific and selective binding sites created within the polymeric matrix turn these complex structures into value-added carriers with tunable features, notably high drug-loading capacity and good control of payload release. MIPs possess considerable promise as synthetic recognition elements in 'theranostics'. Moreover, the high affinity and specificity of MIPs make them more advantageous than other polymer-based nanocomposites. This review summarizes the present state-of-the-art of MIP-based delivery systems for the targeted delivery of bioactives, with current challenges and future perspectives.

Molecularly imprinted polymer-based extended-gate field-effect transistor chemosensors for selective determination of antiepileptic drug

Ultrathin molecularly imprinted polymer (MIP) films were deposited on the surfaces of ZnO nanorods (ZNRs) and nanosheets (ZNSs) by electropolymerization to afford extended-gate field-effect transistor sensors for detecting phenytoin (PHT) in plasma. Molecular imprinting efficiency was optimized by controlling the contents of functional monomers and the template in the precursor solution. PHT sensing was performed in plasma solutions with various concentrations by monitoring the drain current as a function of drain voltage under an applied gate voltage of 1.5 V. The reliability and reproducibility of the fabricated sensors were evaluated through a solution treatment process for complete PHT removal and PHT adsorption-removal cycling, while selectivity was examined by analyzing responses to chemicals with structures analogous to that of PHT. Compared with the ZNS/extracted-MIP sensor and sensors with non-imprinted polymer (NIP) films, the ZNR/extracted-MIP sensor showed superior responses to PHT-containing plasma due to selective PHT adsorption, achieving an imprinting factor of 4.23, detection limit of 12.9 ng/mL, quantitation limit of 53.0 ng/mL, and selectivity coefficients of 3-4 (against tramadol) and ~ 5 (against diphenhydramine). Therefore, we believe that the MIP-based ZNR sensing platform is promising for the practical detection of PHT and other drugs and evaluation of their proper dosages.

Advances in molecularly imprinted materials for selective adsorption of phenolic pollutants from the water environment: Synthesis, applications, and improvement

The application of molecularly imprinted material (MIM) is widely employed as a material for removing phenolic pollutants from the water environment, owing to its exceptional capacity for selective adsorption and high sensitivity. In this paper, the preparation principle, bonding types, and preparation methods of MIM have been comprehensively introduced. Meanwhile, according to the binding type of MIM with phenolic pollutants, three categories of hydroxyl bonding, hydroxyl carboxyl bonding, and hydroxyl nitro bonding were carried out to explain its application to phenolic pollutants. Strategies for addressing the challenges of selective instability, high regeneration costs, and template leakage in MIM applications were summarized. These strategies encompassed the introduction of superior carriers, enhancements in preparation processes, and the utilization of molecular dynamics simulation-assisted technology. Finally, the prospects in the three aspects of material preparation, process coupling, and recycling. In summary, this paper has demonstrated the potential of utilizing MIM for the selective treatment of phenolic pollutants from the water environment.

Progress on Electrochemical Biomimetic Nanosensors for the Detection and Monitoring of Mycotoxins and Pesticides

Monitoring agricultural toxins such as mycotoxins is crucial for a healthy society. High concentrations of these toxins lead to the cause of several chronic diseases; therefore, developing analytical systems for detecting/monitoring agricultural toxins is essential. These toxins are found in crops such as vegetables, fruits, food, and beverage products. Currently, screening of these toxins is mostly performed with sophisticated instrumentation such as chromatography and spectroscopy techniques. However, these techniques are very expensive and require extensive maintenance, and their availability is limited to metro cities only. Alternatively, electrochemical biomimetic sensing methodologies have progressed hugely during the last decade due to their unique advantages like point-of-care sensing, miniaturized instrumentations, and mobile/personalized monitoring systems. Specifically, affinity-based sensing strategies including immunosensors, aptasensors, and molecular imprinted polymers offer tremendous sensitivity, selectivity, and stability to the sensing system. The current review discusses the principal mechanisms and the recent developments in affinity-based sensing methodologies for the detection and continuous monitoring of mycotoxins and pesticides. The core discussion has mainly focused on the fabrication protocols, advantages, and disadvantages of affinity-based sensing systems and different exploited electrochemical transduction techniques.

A zinc-air battery assisted self-powered electrochemical sensor for sensitive detection of microcystin-RR

Building a high-performance sensing platform is the key to developing sensitive sensors. Herein, a highly sensitive self-powered electrochemical sensor (SPES) was constructed using a WO3·H2O film as the cathode prepared by a hydrothermal method and Zn as the anode, and it could be applied to sensitive detection of microcystin (MC-RR). The WO3·H2O film with a larger specific surface area could boost the oxygen reduction reaction (ORR), which could achieve signal amplification and significantly increase the sensitivity of the sensors. Under the optimal conditions, there was a good linear relationship between the increased electrical power density and the logarithm of MC-RR concentration with a detection limit of 1.31 × 10-15 M (S/N = 3). This method had good anti-interference ability and stability when applied to the determination of MC-RR content in actual samples, which could boost the potential application of electrochemical sensors in the field of environmental monitoring.

Preparation of surface molecularly imprinted polymers with Fe3O4/ZIF-8 as carrier for detection of Dimethoate in cabbage

In this study, molecularly imprinted polymers (MIPs) were prepared for the specific recognition of organophosphorus pesticides and a rapid, efficient and simple method was established for the detection of dimethoate (DIT) in food samples. Fe3O4 magnetic nanoparticles were synthesized by co-precipitation, and Fe3O4/ZIF-8 complexes were prepared by a modified in-situ polymerization method, and then magnetic molecularly imprinted polymers (MMIPs) were prepared and synthetic route was optimized by applying density functional theory (DFT). The morphological characterization showed that the MMIPs were coarse porous spheres with an average particle size of 50 nm. The synthesized materials are highly selective for the organophosphorus pesticide dimethoate with an adsorption capacity of 461.50 mg·g-1 and are effective resistance to matrix effects. A novel method for the determination of DIT in cabbage was developed using the prepared MMIPs in combination with HPLC. The practical results showed that the method can meet the requirements for the determination of DIT in cabbage with recoveries of 85.6-121.1 % and detection limits of 0.033 μg·kg-1.

Three-Dimensional Printing of Molecularly Imprinted Polymers by Digital Light Processing for Copper Ion Sequestration

Highly structured, molecularly imprinted polymer (MIP) networks for copper(II) ion sequestration have been realized using the additive manufacturing technology. Photopolymerizable formulations with acrylic functional monomers and two different porogens (water and methanol) in different ratios were studied to produce emulsions with 50 vol% of the internal phase. The results of morphological characterization indicate that all MIPs have cauliflower-like multiscale structures that change as a function of the solvent combination and fabrication process. X-ray fluorescence microscopy maps presented a layered structure and homogeneous distribution of copper in the printed MIP. Copper(II) ion adsorption-desorption tests were performed on MIPs prepared using a three-dimensional (3D) printing approach and MIPs prepared by bulk polymerization. Results indicate that the 3D printed MIP is able to absorb copper up to ten times more efficiently than the nonprinted one and the printed MIP with 100% water content has the highest imprint recognition.

Precise detection of trace level protein using MIP-MoS2 nanocomposite functionalized PCF based interferometer

Fiber optic interferometry combined with recognizing elements has attracted intensive attention for the development of different biosensors due to its superior characteristic features. However, the immobilization of sensing elements alone is not capable of low-concentration detection due to weak interaction with the evanescent field of the sensing transducer. The utilization of different 2D materials with high absorption potential and specific surface area can enhance the intensity of the evanescent field and hence the sensitivity of the sensor. Here, a biosensor has been fabricated using an inline hetero fiber structure of photonic crystal fiber (PCF) and single-mode fiber (SMF) functionalized with a nanocomposite of molybodenum di-sulfide (MoS2) and molecular imprinting polymer (MIP) to detect trace levels of bovine serum albumin (BSA). The sensor showed a wide dynamic detection range with a high sensitivity of 2.34 × 107 pm/µg L-1. It shows working potential over a wide pH range with a subfemtomolar detection limit. The compact size, easy fabrication, stable structure, long detection range, and high sensitivity of this sensor would open a new path for the development of different biosensors for online and remote sensing applications.

Molecularly imprinted dispersive micro solid-phase extraction coupled with high-performance liquid chromatography for the determination of four aflatoxins in various foods

A new dummy template-based molecularly imprinted dispersive micro solid-phase extraction (MI-d-µSPE) coupled with HPLC-FLD developed for the simultaneous determination of four aflatoxins (B1, B2, G1, G2) in various food matrices. The synthesized MIP was used as a dispersive solid-phase extraction (dSPE) sorbent for aflatoxins extraction. The chemometric approach was used to identify the optimum conditions of dSPE. The results showed the amount of MIP sorbent (55 mg), adsorption time (12.5 min), and %ACN (75%) were significant extraction parameters. The method has a detection limit in the range of 0.059-0.208 µg kg-1 and a quantification limit in the range of 0.197-0.694 µg kg-1 for aflatoxins. The intra- and inter-day precision was less than 5%, and recoveries were 79.1-109.4%. The expanded uncertainty of the developed method was found to be 2.9-22.8%. The new MI-d-µSPE with HPLC-FLD method was applied for 37 food matrices.

Multifunctional molecularly imprinted nanozymes with improved enrichment and specificity for organic and inorganic trace compounds

Although nanozymes exhibit properties superior to those of natural enzymes and conventional engineered enzymes, the development of highly specific nanozymes remains a challenge. New yolk-shell Fe3O4 molecularly imprinted (MIP@void@Fe3O4) nanozymes with peroxidase-like activity were developed by modelling the substrate channels of natural enzymes through molecular imprinting techniques and interfacial affinity modifications in this study. To establish a platform technology for the adsorption and determination of inorganic and organic contaminants, lead ion (Pb2+) and diazinon (DIZ), respectively, were selected as imprinting templates, and a hollow mesoporous shell was synthesized. The as-prepared MIP@void@Fe3O4 nanozymes, characterized using TEM, HRTEM, SEM, FT-IR, TGA, VSM and XPS, not only affirmed the successful fabrication of a magnetic nanoparticle with a unique hollow core-shell structure but also facilitated an exploration of the interfacial bonding mechanisms between Fe3O4 and other shell layers. The enrichment of the MIP@void@Fe3O4 nanozymes due to imprinting was approximately 5 times higher than the local substrate concentration and contributed to the increased activity. Based on selective and competitive recognition experiments, the synthesized nanozymes could selectively recognize organic and inorganic targets with the lowest detection limits (LOD) of 6.6 × 10-9 ppm for Pb2+ and 5.13 × 10-11 M for DIZ. Therefore, the proposed biosensor is expected to be a potent tool for trace pollutant detection, which provides a rational design for more advanced and subtle methods to bridge the activity gap between natural enzymes and nanozymes.

Molecularly Imprinted Heterostructure-Based Electrochemosensor for Ultratrace and Precise Detection of 2-Methylisoborneol in Water

Ultratrace 2-methylisoborneol (2-MIB, ∼ng/L) in source water is the main odorant in the algae-derived odor episodes, whose accurate on-site detection will have a promising application potential. Due to the chemical inertness of 2-MIB, sensitive and selective detection of 2-MIB remains much challenging. Herein, molecularly imprinted polymer cavities were polymerized on the heterostructure Ti3C2Tx@CuFc-metal-organic framework to selectively capture 2-MIB, where the heterostructure could catalyze the probe redox reaction of [Fe(CN)63-/4-] and amplify the corresponding current signals. The prepared electrochemical sensor showed higher sensitivity on 2-MIB detection than the reported ones. Excellent stability, reusability, and selectivity for 2-MIB detection were also verified. The linear range and limit of detection of our sensor for 2-MIB were optimized to 0.0001-100 μg/L and 30 pg/L, respectively, performing much better than the reported sensors. Comparable performance to gas chromatography-mass spectrometry was achieved when the sensor was applied to real water samples with or without 2-MIB standards. Overall, our research has made great progress in the application of an on-site sensor in 2-MIB detection and well advances the development of molecularly imprinted polymer-based electrochemical sensors.

Dendrimer Coated Silica as a Sorbent for Dispersive Solid-Phase Extraction of Select Non-Steroidal Anti-Inflammatory Drugs from Water

Non-steroidal anti-inflammatory drugs (NSAIDs) have been recognized as a potentially serious threat to the natural environment. NSAIDs are popular painkillers, and the main pathway for them to reach natural water is via discharge from wastewater and sewage treatment plants. In order to monitor contamination caused by these drugs, as well as their impact on the environment, a new material based on Silica Gel 60, functionalized with a dendrimeric copolymer of methylamine and 1,4-butanediol diglycidyl ether (named MA-BDDE), was prepared. Initial physicochemical characterization of the MA-BDDE material was carried out using ATR FT-IR spectroscopy as well as solid-state carbon-13 NMR spectroscopy. Its effectiveness at NSAID extraction was evaluated by the application of five select drugs in dispersive solid-phase extraction (dSPE): aspirin, ketoprofen, naproxen, diclofenac and ibuprofen. This was followed by their simultaneous determination using the HPLC-UV/Vis system demonstrating good sensitivity, with limits of detection values within the 63-265 ng mL-1 range. A comparison of the sorption capacity of each pharmaceutical with unmodified base silica showed an at least tenfold increase in capacity after modification. Initial MA-BDDE application in a quick, low-waste extraction procedure of those select NSAIDs from spiked surface water samples yielded promising results for its use as a sorbent, as recovery values of analytes adsorbed from various samples were found to exceed 72%.

Molecularly imprinted polymers by reflux precipitation polymerization for selective solid-phase extraction of quinolone antibiotics from urine

Molecularly imprinted polymers (MIPs) possess high specific cavities towards the template molecules, thus solid-phase extraction (SPE) based on MIPs using the target as the template has been widely used for selective extraction. However, the performance of SPE depends strongly on the shape and the distribution of the MIP sorbents, and rapid synthesis of MIPs with uniform particles remains a challenge. Our previous studies have shown that reflux precipitation polymerization (RPP) was a simple and rapid method for the synthesis of uniform MIPs. However, synthesis of MIPs by RPP for a group of targets using only one of the targets as the template has rarely been reported. In this work, MIPs with specific recognition capability for a group of quinolone antibiotics were synthesized for the first time via RPP with only ofloxacin as the template. The synthesized MIPs displayed good adsorption performance and selectivity (IF > 3.5) towards five quinolones, and subsequently were used as SPE adsorbents. Based on this MIPs-SPE, after systematic optimization of the SPE operation parameters during loading, washing and elution, an efficient and sensitive enough SPE method for separation and enrichment of the five quinolones in urine was developed and evaluated in combination with LC-MS/MS. The results showed that MIPs-SPE-LC-MS/MS has a good correlation (R2 ≥ 0.9961) in the linear range of 1-500 μg L-1. The limit of detection (LOD) and limit of quantification (LOQ) for the five quinolones were 0.10-0.14 μg L-1 and 0.32-0.48 μg L-1, respectively. In addition, the proposed method demonstrated good reproducibility (≤ 13 %) and high accuracy (92 %-113 %). We are confident that this method holds significant promise for the analysis of quinolones within the contexts of forensic medicine, epidemiology, and environmental chemistry.

Bibliometric research analysis of molecularly imprinted polymers (MIPs): evidence and research activity dynamics

The escalating issue of water pollution has become a worldwide issue that has captured the attention of numerous scientists. Molecularly imprinted polymers (MIPs) have emerged as adaptable materials with exceptional attributes, including easy synthesis, low cost, remarkable durability, long life, and accessibility. These attributes have motivated researchers to develop novel materials based on MIPs to tackle hazardous contaminants in environmental matrices. The purpose of this paper was to conduct a bibliometric analysis on MIPs' publications, in order to shed light on the developments and focus points of the field. The selected publications were obtained from Scopus database and subjected to a filtering process, resulting in 11,131 relevant publications. The analysis revealed that the leading publication source (journal) is Biosensors and Bioelectronics; the mostly employed keywords are solid-phase extraction, electrochemical sensor, and molecular recognition; and the top contributing countries are China, Iran, and the USA. The Latent Dirichlet Allocation (LDA) algorithm was used for extracting thematic axes from the textual content of the publications. The results of the LDA model showcase that the topic of synthesis and performance of MIPs for environmental applications can be considered as the most dominant topic with a share value of 72.71%. From the analysis, it can be concluded that MIPs are a cross-disciplinary research field.

Occurrence, toxicity, impact and removal of selected non-steroidal anti-inflammatory drugs (NSAIDs): A review

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most frequently used pharmaceuticals for human therapy, pet therapeutics, and veterinary feeds, enabling them to enter into water sources such as wastewater, soil and sediment, and seawater. The control of NSAIDs has led to the advent of the novel materials for treatment techniques. Herein, we review the occurrence, impact and toxicity of NSAIDs against aquatic microorganisms, plants and humans. Typical NSAIDs, e.g., ibuprofen, ketoprofen, diclofenac, naproxen and aspirin were detected at high concentrations in wastewater up to 2,747,000 ng L-1. NSAIDs in water could cause genotoxicity, endocrine disruption, locomotive disorders, body deformations, organs damage, and photosynthetic corruption. Considering treatment methods, among adsorbents for removal of NSAIDs from water, metal-organic frameworks (10.7-638 mg g-1) and advanced porous carbons (7.4-400 mg g-1) were the most robust. Therefore, these carbon-based adsorbents showed promise in efficiency for the treatment of NSAIDs.

Determination of tetrabromobisphenol A and its brominated derivatives in water, sediment and soil by high performance liquid chromatography-tandem mass spectrometry

Tetrabromobisphenol A (TBBPA) was typical brominated flame retardant and potential environmental endocrine disruptor, and it had persistence, bioaccumulation and chronic toxicity. Simultaneous determination of ultra-trace TBBPA, tribromobiphenol A (tri-BBPA), dibromobiphenol A (di-BBPA), monobromobisphenol A (mono-BBPA) and bisphenol A (BPA) was developed by high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS), the parent ion charge ratios (m/z) had been optimized. The linear range was wider and the limit of detection was (LOD) 0.09 ~ 0.21 ng mL-1, which could detect trace pollutants. The extraction efficiency was improved by optimizing the parameters, HLB cartridge was used in the water sample by solid phase extraction (SPE), the recovery rates in water samples were over 80.28% with three concentration levels, the relative standard deviations (RSD) were less than 7.12%, and the minimum detection limit of the method was 0.90 ~ 2.10 × 10-3 ng mL-1. Soil and sediment samples were extracted by accelerated solvent extraction (ASE), the recovery rates in soil and sediment were over 79.40% and 75.65%, the minimum detection limit was 0.0225 ~ 0.0525 ng g-1, RSD was less than 7.19%. The proffered method was successfully utilized to detect actual samples, the residue of di-BBPA and mono-BBPA are detected in Naihe River and Shuxi River in Tai'an City, residue of di-BBPA and mono-BBPA was detected in the soil, and there was low residual amount of di-BBPA, mono-BBPA and BPA in the sediment of Shuxi River.

Cellulose-based adsorbents for solid phase extraction and recovery of pharmaceutical residues from water

Cellulose has attracted interest from researchers both in academic and industrial sectors due to its unique structural and physicochemical properties. The ease of surface modification of cellulose by the integration of nanomaterials, magnetic components, metal organic frameworks and polymers has made them a promising adsorbent for solid phase extraction of emerging contaminants, including pharmaceutical residues. This review summarizes, compares, and contrasts different types of cellulose-based adsorbents along with their applications in adsorption, extraction and pre-concentration of pharmaceutical residues in water for subsequent analysis. In addition, a comparison in efficiency of cellulose-based adsorbents and other types of adsorbents that have been used for the extraction of pharmaceuticals in water is presented. From our observation, cellulose-based materials have principally been investigated for the adsorption of pharmaceuticals in water. However, this review aims to shift the focus of researchers to the application of these adsorbents in the effective pre-concentration of pharmaceutical pollutants from water at trace concentrations, for quantification. At the end of the review, the challenges and future perspectives regarding cellulose-based adsorbents are discussed, thus providing an in-depth overview of the current state of the art in cellulose hybrid adsorbents for extraction of pharmaceuticals from water. This is expected to inspire the development of solid phase exraction materials that are efficient, relatively cheap, and prepared in a sustainable way.

Recent Developments in the Detection of Organic Contaminants Using Molecularly Imprinted Polymers Combined with Various Analytical Techniques

Molecularly imprinted polymers (MIPs) encompass a diverse array of polymeric matrices that exhibit the unique capacity to selectively identify a designated template molecule through specific chemical moieties. Thanks to their pivotal attributes, including exceptional selectivity, extended shelf stability, and other distinct characteristics, this class of compounds has garnered interest in the development of highly responsive sensor systems. As a result, the incorporation of MIPs in crafting distinctive sensors and analytical procedures tailored for specific analytes across various domains has increasingly become a common practice within contemporary analytical chemistry. Furthermore, the range of polymers amenable to MIP formulation significantly influences the potential utilization of both conventional and innovative analytical methodologies. This versatility expands the array of possibilities in which MIP-based sensing can be employed in recognition systems. The following review summarizes the notable progress achieved within the preceding seven-year period in employing MIP-based sensing techniques for analyte determination.

Molecularly imprinted polymers (MIPs) as efficient catalytic tools for the oxidative degradation of 4-nonylphenol and its by-products

Water pollution is a current global concern caused by emerging pollutants like nonylphenol (NP). This endocrine disruptor cannot be efficiently removed with traditional wastewater treatment plants (WTPs). Therefore, this work aimed to evaluate the adsorption influence of molecularly imprinted polymers (MIPs) on the oxidative degradation (ozone and ultraviolet irradiations) of 4-nonylphenol (4-NP) and its by-products as a coadjuvant in WTPs. MIPs were synthesized and characterized; the effect of the degradation rate under system operating conditions was studied by Box-Behnken response surface design of experiments. The variables evaluated were 4-NP concentration, ozone exposure time, pH, and MIP amount. Results show that the MIPs synthesized by co-precipitation and bulk polymerizations obtained the highest retention rates (> 90%). The maximum adsorption capacities for 4-NP were 201.1 mg L-1 and 500 mg L-1, respectively. The degradation percentages under O3 and UV conditions reached 98-100% at 120 s of exposure at different pHs. The degradation products of 4-NP were compounds with carboxylic and ketonic acids, and the MIP adsorption was between 50 and 60%. Our results present the first application of MIPs in oxidation processes for 4-NP, representing starting points for the use of highly selective materials to identify and remove emerging pollutants and their degradation by-products in environmental matrices.

Application of Chitosan-Based Molecularly Imprinted Polymer in Development of Electrochemical Sensor for p-Aminophenol Determination

Molecularly Imprinted Polymers (MIPs) have specific recognition capabilities and have been widely used for electrochemical sensors with high selectivity. In this study, an electrochemical sensor was developed for the determination of p-aminophenol (p-AP) by modifying the screen-printed carbon electrode (SPCE) with chitosan-based MIP. The MIP was made from p-AP as a template, chitosan (CH) as a base polymer, and glutaraldehyde and sodium tripolyphosphate as the crosslinkers. MIP characterization was conducted based on membrane surface morphology, FT-IR spectrum, and electrochemical properties of the modified SPCE. The results showed that the MIP was able to selectively accumulate analytes on the electrode surface, in which MIP with glutaraldehyde as a crosslinker was able to increase the signal. Under optimum conditions, the anodic peak current from the sensor increased linearly in the range of 0.5-35 µM p-AP concentration, with sensitivity of (3.6 ± 0.1) µA/µM, detection limit (S/N = 3) of (2.1 ± 0.1) µM, and quantification limit of (7.5 ± 0.1) µM. In addition, the developed sensor exhibited high selectivity with an accuracy of (94.11 ± 0.01)%.

Molecularly imprinted polymers for per- and polyfluoroalkyl substances enrichment and detection

Per- and polyfluoroalkyl substances (PFAS) are highly toxic pollutants of significant concern as they are being detected in water, air, fish and soil. They are extremely persistent and accumulate in plant and animal tissues. Traditional methods of detection and removal of these substances use specialised instrumentation and require a trained technical resource for operation. Molecularly imprinted polymers (MIPs), polymeric materials with predetermined selectivity for a target molecule, have recently begun to be exploited in technologies for the selective removal and monitoring of PFAS in environmental waters. This review offers a comprehensive overview of recent developments in MIPs, both as adsorbents for PFAS removal and sensors that selectively detect PFAS at environmentally-relevant concentrations. PFAS-MIP adsorbents are classified according to their method of preparation (e.g., bulk or precipitation polymerization, surface imprinting), while PFAS-MIP sensing materials are described and discussed according to the transduction methods used (e.g., electrochemical, optical). This review aims to comprehensively discuss the PFAS-MIP research field. The efficacy and challenges facing the different applications of these materials in environmental water applications are discussed, as well as a perspective on challenges for this field that need to be overcome before exploitation of the technology can be fully realised.

Advancements in Clay Materials for Trace Level Determination and Remediation of Phenols from Wastewater: A Review

The wide spread of phenols and their toxicity in the environment pose a severe threat to the existence and sustainability of living organisms. Rapid detection of these pollutants in wastewaters has attracted the attention of researchers from various fields of environmental science and engineering. Discoveries regarding materials and method developments are deemed necessary for the effective detection and remediation of wastewater. Although various advanced materials such as organic and inorganic materials have been developed, secondary pollution due to material leaching has become a major concern. Therefore, a natural-based material is preferable. Clay is one of the potential natural-based sorbents for the detection and remediation of phenols. It has a high porosity and polarity, good mechanical strength, moisture resistance, chemical and thermal stability, and cation exchange capacity, which will benefit the detection and adsorptive removal of phenols. Several attempts have been made to improve the capabilities of natural clay as sorbent. This manuscript will discuss the potential of clays as sorbents for the remediation of phenols. The activation, modification, and application of clays have been discussed. The achievements, challenges, and concluding remarks were provided.

In-Situ Construction Molecular Imprinting Electrocatalyst of Au-MoO3/Graphene for Bisphenol A Determination with Long-Term Stability

Molecular imprinting (MI) technology has been used in electrochemical analysis technology because of its unique selectivity and specificity. In this work, an electrochemical sensor based on in-situ inorganic MI-Au-MoO3/graphene for bisphenol A (BPA) analysis is designed, where MI-MoO3 is hybridized with graphene nanosheets and Au nanoparticles, and BPA is acted as the temple molecular. Differential pulse voltammetry (DPV) was used to evaluate the sensing performance of the MI-Au-MoO3/rGO sensor toward BPA determination and it is about 2.0 times that of NI-Au-MoO3/rGO. The as-constructed sensor presents a wide linear range from 0.01 to 106.04 μM and a low limit of detection of 0.003 μM. It also displays outstanding stability and repeatability up to 20 days, and can be used to analyze the content of BPA in dust leachate and plastic bottle. This sensor offers a promising strategy for environment pollution and food analysis via MI technology.

Application of Molecularly Imprinted Electrochemical Biomimetic Sensors for Detecting Small Molecule Food Contaminants

Environmental chemical contaminants in food seriously impact human health and food safety. Successful detection methods can effectively monitor the potential risk of emerging chemical contaminants. Among them, molecularly imprinted polymers (MIPs) based on electrochemical biomimetic sensors overcome many drawbacks of conventional detection methods and offer opportunities to detect contaminants with simple equipment in an efficient, sensitive, and low-cost manner. We searched eligible papers through the Web of Science (2000-2022) and PubMed databases. Then, we introduced the sensing mechanism of MIPs, outlined the sample preparation methods, and summarized the MIP characterization and performance. The classification of electrochemistry, as well as its advantages and disadvantages, are also discussed. Furthermore, the representative application of MIP-based electrochemical biomimetic sensors for detecting small molecular chemical contaminants, such as antibiotics, pesticides, toxins, food additives, illegal additions, organic pollutants, and heavy metal ions in food, is demonstrated. Finally, the conclusions and future perspectives are summarized and discussed.

Preparation and Adsorption Properties of Magnetic Molecularly Imprinted Polymers for Selective Recognition of 17β-Estradiol

In this paper, magnetic molecularly imprinted polymers (MMIPs) were fabricated on the surface of Fe3O4 by surface molecular imprinting technology, which can selectively adsorb 17β-estradiol (E2). The optimized experiments demonstrated that MMIPs possessed the best adsorption capacity when methanol was used as the solvent and MAA was used as the crosslinking agent, with a molar ratio of E2: MMA: EGDMA as 1:4:50. SEM, FTIR, and XRD were employed to investigate the morphologies of MMIPs and the results demonstrated that the MMIPs that can selectively adsorb E2 were successfully prepared on Fe3O4 particles. The adsorption experiments showed that 92.1% of E2 was adsorbed by the MMIPs, which is higher than the magnetic non-molecularly imprinted polymers (MNIPs). The Freundlich isotherm model was more suitable to describe the adsorption process of E2 by MMIPs. Meanwhile, MMIPs had a better recognition ability for E2 and its structural analogs such as estrone and estriol. The MMIPs still had good adsorption performance after methanol regeneration five times. The prepared MMIPs had the advantages of efficient adsorption ability and high reusability, so they can be applied for selective recognition and removal of E2.

Method of Glyphosate, AMPA, and Glufosinate Ammonium Determination in Beebread by Liquid Chromatography-Tandem Mass Spectrometry after Molecularly Imprinted Solid-Phase Extraction

The aim of this study was to develop a method for the determination of glyphosate, its metabolite aminomethylphosphonic acid (AMPA), and glufosinate ammonium residues in beebread samples, which could then be used to assess bees' exposure to their residues. The complexity of beebread's matrix, combined with the specific properties of glyphosate itself, required careful selection and optimization of each analysis step. The use of molecularly imprinted solid-phase extraction (MIP-SPE) by AFFINIMIP glyphosate as an initial clean-up step significantly eliminated matrix components and ensured an efficient derivatization step. Colorless beebread extracts were derivatized by the addition of 9-fluorenylmethyl chloroformate (FMOC-Cl). After derivatization, in order to remove FMOC-OH and residual borate buffer, a solid-phase extraction (SPE) clean-up step using Oasis HLB was carried out. Instrumental analysis was performed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The method was validated according to the SANTE/11312/2021 guideline at concentrations of 5, 10, and 100 µg/kg, and satisfactory recovery (trueness) values (76-111%) and precision (RSDr) ≤ 18% were obtained. The limit of quantification (LOQ) was 5 µg/kg for AMPA and glufosinate ammonium and 10 µg/kg for glyphosate. The method was positively verified by the international proficiency test. Analysis of beebread samples showed the method's usefulness in practice. The developed method could be a reliable tool for the assessment of beebread's contamination with residues of glyphosate, its metabolite AMPA, and glufosinate ammonium.

Advances in fabrication of molecularly imprinted electrochemical sensors for detection of contaminants and toxicants

Worldwide growing concerns about water contamination and pollution have increased significant interest in trace level sensing of variety of contaminants. Thus, there is demand for fabrication of low cost, miniaturized sensing device for in-situ detection of contaminants from the complex environmental matrices capable of providing selective and sensitive detection. Molecularly imprinted polymers (MIPs) has portrayed a substantial potential for selective recognition of various toxicants from a variety of environmental matrices, thus widely used as artificial recognition element in the electrochemical sensors (ECS) owing to their chemical stability, easy and low cost synthesis. The combination of nanomaterials modifiers with MIPs has endowed MIP-ECS with significantly improved sensing performance in the recent years, as the nanomaterial provide properties such as increased surface area, increased conductivity and electrocatalytic activity with enhanced electron transport phenomena, whereas MIPs provide selective recognition effect. In the present review, we have summarized the advances of MIP-ECS electrochemical sensors reported in last six years (2017-2022) for sensing of variety of contaminates including drugs, metal ions, hormones and emerging contaminates. Scope of computational modelling in design of sensitive and selective MIP-ECS is reviewed. We have focused particularly on the synthetic protocols for MIPs preparation including bulk, precipitation, electropolymerization, sol-gel and magnetic MIPs. Moreover, use of various nanomaterial as modifiers and sensitizers and their effects on the sensing performance of resulting MIP-ECS is described. Finally, the potential challenges and future prospects in the research area of MIP-ECS have been discussed.

Preparation of metal-organic framework @molecularly imprinted polymers for extracting strobilurin fungicides from agricultural products

The core-shell metal-organic framework coated with molecularly imprinted polymers (ZIF-8@MIPs) were successfully synthesized by surface imprinting technique, and applied as adsorbents for solid-phase extraction of strobilurin fungicides. The obtained hybrid complex was characterized in detail, and their adsorbing and recognition performance were evaluated. The results showed that ZIF-8@MIPs presented typically core-shell structure with MIP shell (about 20 nm), and exhibited larger adsorption capacity (102.5 mg g^-1) and fast adsorption ability (only 5 min). Under the optimized conditions, a sensitive, efficient and reliable method for determining six strobilurin fungicides in different agricultural products based on ZIF-8@MIPs coupling with high performance liquid chromatography-tandem mass spectrometry was established. This method showed good linearity with correlation coefficients higher than 0.9990. With spiked at three different concentration levels in agricultural products (apple, pear, banana, Chinese cabbage, cabbage, cucumber), the good recoveries (83.5-129.0%) with relative standard deviations from 0.5 to 10.2% were obtained. The limit of detections and the limit of quantifications were 0.01-1.12 ng g^-1 and 0.03-3.73 ng g^-1, respectively. Those results demonstrated good potential application of ZIF-8@MIPs for enriching and separating trace strobilurin fungicides in agricultural samples.

Polyoxometalate-based materials in extraction, and electrochemical and optical detection methods: A review

Polyoxometalates (POMs) as metal-oxide anions have exceptional properties like high negative charges, remarkable redox abilities, unique ligand properties and availability of organic grafting. Moreover, the amenability of POMs to modification with different materials makes them suitable as precursors to further obtain new composites. Due to their unique attributes, POMs and their composites have been utilized as adsorbents, electrodes and catalysts in extraction, and electrochemical and optical detection methods, respectively. A survey of the recent progress and developments of POM-based materials in these methods is therefore desirable, and should be of great interest. In this review article, POM-based materials, their properties as well as their identification methods, and analytical applications as adsorbents, electrodes and catalysts, and corresponding mechanisms of action, where relevant, are reviewed. Some current issues of the utilization of these materials and their future prospects in analytical chemistry are discussed.

Molecularly imprinted polymers: preparation, characterisation, and application in drug delivery systems

Molecular imprinting technology defines the creation of molecularly imprinted polymer (MIP) molecules in which template molecules can place in a key-lock relationship through shape, diameter, and functional groups. Although molecular imprinting technology has been employed in different fields, its applications in drug delivery systems (DDSs) have gained momentum recently. The high loading efficiency, high stability, and controlled drug release are the primary advantages of MIPs. Here, the main components, preparation methods, and characterisation tests of MIPs are summarised, and their applications in DDSs administered by different routes are evaluated in detail. The review offers a perspective on molecular imprinting technology and applications of MIPs in drug delivery by surveying the literature approximately 1998-2021 together with the outlined prospects.

Molecularly imprinted polymers via reversible addition-fragmentation chain-transfer synthesis in sensing and environmental applications

Molecularly imprinted polymers (MIP) have shown their potential as artificial and selective receptors for environmental monitoring. These materials can be tailor-made to achieve a specific binding event with a template through a chosen mechanism. They are capable of emulating the recognition capacity of biological receptors with superior stability and versatility of integration in sensing platforms. Commonly, these polymers are produced by traditional free radical bulk polymerization (FRP) which may not be the most suitable for enhancing the intended properties due to the poor imprinting performance. To improve the imprinting technique and the polymer capabilities, controlled/living radical polymerization (CRP) has been used to overcome the main drawbacks of FRP. Combining CRP techniques such as RAFT (reversible addition-fragmentation chain transfer) with MIP has achieved higher selectivity, sensitivity, and sorption capacity of these polymers when implemented as the transductor element in sensors. The present work focuses on RAFT-MIP design and synthesis strategies to enhance the binding affinities and their implementation in environmental contaminant sensing applications.

Sponge-like porous manganese(II, III) oxide as a coating for solvent-assisted solid-phase microextraction of polycyclic aromatic hydrocarbons followed by gas chromatography-mass spectrometry

A nanostructure sponge-like porous manganese(II, III) oxide was synthesized and applied as a new fiber coating for solvent-assisted solid-phase microextraction. The synthesized material was characterized via Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and N₂ adsorption/desorption techniques. To investigate the extraction performance of the prepared material, direct immersion solid-phase microextraction followed by gas chromatography-mass spectrometry was used for the determination of the selected polycyclic aromatic hydrocarbons in wastewater samples. Three polycyclic aromatic hydrocarbons including 1-methylnaphthalene, anthracene, and pyrene were selected as model analytes. To maximize the sensitivity of the method, key experimental factors affecting the extraction efficiency of the analytes such as ionic strength, extraction solvent, stirring rate, extraction temperature and time, and desorption temperature and time were optimized. The applicability of the new coating material for the extraction of the selected analytes from wastewater samples was evaluated. Under the optimum conditions, detection limits between 0.7 and 1.5 ng L^-1 were obtained for the model analytes. The linear dynamic range was 5.0-3.0 × 10³ ng L^-1 for all the analytes. Relative standard deviations were between 2 and 11%. In the case of real sample analysis, the extraction recoveries of the analytes were obtained in the range of 77-111%.

Molecular Imprinting Using a Functional Chain Transfer Agent

This study demonstrates the feasibility of molecular imprinting using a functional chain transfer agent sans a functional monomer. Ethylene glycol dimethacrylate (EGDMA)-based MIPs were synthesised in the presence of thioglycolic acid (TGA) possessing a carboxylic acid group, capable of interacting with the chosen test template R,S-(±)-propranolol (PNL) and a labile S-H bond to facilitate an efficient chain transfer reaction. Quantitative ¹H NMR measurements showed high PNL and TGA incorporation within the MIP, indicating an efficient chain transfer process and a favourable interaction between PNL and TGA. TGA-50, with the lowest amount of CTA, showed the largest imprinting effect and an imprinting factor (IF) of 2.1. The addition of MAA to the formulation improved the binding capacity of PNL to the MIP but also increased NIP binding, resulting in a slightly decreased IF of 1.5. The K_d for the high-affinity sites of the TGA/MAA MIP were found to be two times lower (10 ± 1 μM) than that for the high-affinity sites of the TGA-only MIPs, suggesting that the incorporation of the functional monomer MAA increases the affinity towards the PNL template. Selectivity studies, cross-reactivity as well as binary competitive and displacement assays showed the TGA-based MIPs to be highly selective towards PNL against pindolol and slightly competitive against atenolol. The morphologies of the polymers were shown to be affected by the concentration of the TGA, transforming into discrete macrospheres (from small aggregates) at a higher TGA concentration.

Miniaturized green sample preparation approaches for pharmaceutical analysis

The development of green sample preparation procedures is an extremely important research field in which more and more applications are constantly being proposed in different areas, including pharmaceutical analysis. This review article is aimed at providing a general overview of the development of miniaturized green analytical sample preparation procedures in the pharmaceutical analysis field, with special focus on the works published between January 2017 and July 2021. Particular attention has been paid to the application of environmentally friendly solvents and sorbents as well as nanomaterials or high extraction capacity sorbents in which the solvent volumes and reagents amounts are drastically reduced, with their subsequent advantages from the sustainability point of view.

Molecular imprinted polymer combined with aptamer (MIP-aptamer) as a hybrid dual recognition element for bio(chemical) sensing applications. Review

The development of diagnostic devices based on memetic molecular recognitions are becoming highly promising due to high specificity, sensitivity, stability, and low-cost comparing to natural molecular recognition. During the last decade, molecular imprinted polymers (MIPs) and aptamer have shown dramatic enhancement in the molecular recognition characteristics for bio(chemical) sensing applications. Recently, MIP-aptamer, as an emerging hybrid recognition element, merged the advantages of the both recognition components. This dual recognition-based sensor has shown improved properties and desirable features, such as high sensitivity, low limit of detection, high stability under harsh environmental conditions, high binding affinity, and superior selectivity. Hybrid MIP-aptamer as dual recognition element, was used in the real sample analysis, such as detection of proteins, neurotransmitters, environmental pollutants, biogenic compounds, small ions, explosives, virus detections and pharmaceuticals. This review focuses on a comprehensive overview of the preparation strategies of various MIP-aptamer recognition elements, mechanism of formation of MIP-aptamer, and detection of various target molecules in different matrices.