Multi-templates surface molecularly imprinted polymer for rapid separation and analysis of quinolones in water

Preparation of Zn/Zr-MOFs by microwave-assisted ball milling and adsorption of lomefloxacin hydrochloride and levofloxacin hydrochloride in wastewater

The Zn/Zr-MOFs were synthesized via microwave-assisted ball milling and subsequently characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The thermal stability of the Zn/Zr-MOFs was evaluated through thermogravimetry (TGA). The results demonstrated the exceptional adsorption properties of the Zn/Zr-MOFs towards Lomefloxacin hydrochloride and Levofloxacin hydrochloride. At a concentration of 30 ppm for Lomefloxacin hydrochloride, the addition of 30 mg of Zn/Zr-MOFs material resulted in an adsorption capacity of 179.2 mg•g-1. Similarly, at a concentration of 40 ppm for Levofloxacin hydrochloride, the addition of 30 mg Zn/Zr-MOFs material led to an adsorption capacity of 187.1 mg•g-1. Kinetic analysis revealed that the experimental data aligned well with a pseudo-second order kinetic model. Overall, these findings highlight the significant potential application of Zn/Zr-MOF materials in wastewater treatment.

Development of a molecularly imprinted polymer on silanized graphene oxide for the detection of 17-estradiol in wastewater

This research article demonstrates the synthesis, characterization, and electrochemical evaluation of a molecularly imprinted polymer (MIP) on the surface of silanized graphene oxide (silanized GO), which is nanostructured and used to quantify 17-estradiol (E2) in wastewater. As characterization methods, X-ray diffraction (XRD), Raman spectroscopy, dynamic scattering light (DSL), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) were utilized to examine the synthesized GO, silanized GO, MIP-GO composite, and non-imprinted polymer (NIP)-GO (NIP-GO) composite. FTIR results confirmed the successful synthesis of GO composites. Raman study confirmed the synthesis of monolayer silanized GO, MIP-GO composite, and NIP-GO composite. Surface morphology revealed that after polymerization, the surface of silanized GO sheet-like morphology is covered with nanoparticles. Adsorption kinetics studies revealed that adsorption follows the pseudo-second-order kinetics. Further, we studied the performance of a MIP-GO-based sensor by optimizing the effects of pH, scan rate, and incubation period. The linear calibration was achieved between the oxidation peak current and E2 concentration from 0.1 to 0.81 ppm, with a detection limit of 0.037 ppm. The selectivity of the MIP-GO composite was also checked by using other estrogens, and it was found that E2 is 3.3, 0.5, and 1.4 times more selective than equilin, estriol, and estrone, respectively. The composite was successfully applied to the wastewater samples for the detection of E2, and a good percentage of recoveries were achieved. It suggests that the reported composite can be applied to real samples. PRACTITIONER POINTS: An innovative electrochemical sensor was developed for selective detection of 17-estradiol through molecularly imprinted polymer fabricated on the surface of silanized GO (MIP-GO composite). The developed method was comprehensively validated and found to be linear in the range of 0.1 to 0.8 ppm of 17-estradiol, with 0.037 ppm of limit of detection and 0.1 ppm of limit of quantification, respectively. The developed MIP-GO-composite-based electrochemical sensor was found 3.3, 0.5, and 1.4 times more selective for 17-estradiol than equiline, estriol, and estrone, respectively. The applicability of a developed sensor was also checked on wastewater samples, and a good percent recovery was obtained.

One-pot preparation of magnetic molecularly imprinted adsorbent with dual template molecules for simultaneously specific capture of sulfonamides and quinolones in water and milk samples

Specific capture is a beneficial tactic in simultaneous monitoring of sulfonamides (SAs) and quinolones (QLs). For this purpose, a new magnetic molecularly imprinted adsorbent based on double-template molecules (DT-MIP@MNA) was facilely prepared by "one-pot" hydrothermal technique and utilized as the adsorbent of magnetic solid-phase extraction (MSPE). Molecular simulation technique was employed to quickly screen functional monomer. The recognition factors of prepared adsorbent towards templates sulfamethazine and nalidixic acid were 5.89 and 2.90, respectively, and the corresponding adsorption capacities were as high as 8.85 mg/g and 8.97 mg/g, respectively. Under the optimized parameters, the proposed DT-MIP@MNA/MSPE was combined with HPLC to simultaneously and selectively monitor trace SAs and QLs residuals in water and milk samples. The achieved limits of detection were 0.012-0.028 μg/L and 0.015-0.032 μg/kg for water and milk samples, respectively. The current supplied a sensitive, reliable and anti-interference method for simultaneously monitoring trace SAs and QLs in food.

Synthesis and Properties of Cefixime Core-Shell Magnetic Nano-Molecularly Imprinted Materials

Novel core-shell magnetic molecularly imprinted polymers (MMIPs) were synthesized using the sol-gel method for the adsorption of cefixime (CFX). Fe3O4@SiO2 is the core, and molecularly imprinted polymers (MIPs) are the shell, which can selectively interact with CFX. The preparation conditions, adsorption kinetics, adsorption isotherms, selective adsorption ability, and reutilization performance of the MMIPs were investigated. The adsorption capacity of MMIPs for CFX was 111.38 mg/g, which was about 3.5 times that of MNIPs. The adsorption equilibrium time was 180 min. The dynamic adsorption experiments showed that the adsorption process of MMIPs to CFX conformed to the pseudo-second-order model. Through static adsorption study, the Scatchard analysis showed that MMIPs had two types of binding sites-the high-affinity binding sites and the low-affinity binding sites-while the Langmuir model fit the adsorption isotherms well (R2 = 0.9962). Cefepime and ceftiofur were selected as the structural analogs of CFX for selective adsorption studies; the adsorption of CFX by MMIPs was higher than that of other structural analogs; and the imprinting factors of CFX, cefepime, and ceftiofur were 3.5, 1.7, and 1.4, respectively. Furthermore, the MMIPs also showed excellent reusable performance.

Molecularly Imprinted Polymers for Pharmaceutical Impurities: Design and Synthesis Methods

The safety of a medicinal product is determined by its pharmacological and toxicological profile, which depends not only on the active substance's toxicological properties, but also on the impurities it contains. Because impurities are a problem that must be considered to ensure the safety of a drug product, many studies have been conducted regarding the separation or purification of active pharmaceutical ingredients (APIs) and the determination of impurities in APIs and drug products. Several studies have applied molecularly imprinted polymers (MIPs) to separate impurities in active ingredients and as adsorbents in the sample preparation process. This review presents the design of MIPs and the methods used to synthesise MIPs to separate impurities in APIs and drug product samples, the application of MIPs to separate impurities, and a view of future studies involving MIPs to remove impurities from pharmaceutical products. Based on a comparison of the bulk and surface-imprinting polymerisation methods, the MIPs produced by the surface-imprinting polymerisation method have a higher adsorption capacity and faster adsorption kinetics than the MIPs produced by the bulk polymerisation method. However, the application of MIPs in the analysis of APIs and drug products are currently only related to organic compounds. Considering the advantages of MIPs to separate impurities, MIPs for other impurities still need to be developed, including multi-template MIPs for simultaneous separation of multiple impurities.

In situ synthesis and dynamic simulation of molecularly imprinted polymeric nanoparticles on a micro-reactor system

Current practices in synthesizing molecularly imprinted polymers face challenges-lengthy process, low-productivity, the need for expensive and sophisticated equipment, and they cannot be controlled in situ synthesis. Herein, we present a micro-reactor for in situ and continuously synthesizing trillions of molecularly imprinted polymeric nanoparticles that contain molecular fingerprints of bovine serum albumin in a short period of time (5-30 min). Initially, we performed COMSOL simulation to analyze mixing efficiency with altering flow rates, and experimentally validated the platform for synthesizing nanoparticles with sizes ranging from 52-106 nm. Molecular interactions between monomers and protein were also examined by molecular docking and dynamics simulations. Afterwards, we benchmarked the micro-reactor parameters through dispersity and concentration of molecularly imprinted polymers using principal component analysis. Sensing assets of molecularly imprinted polymers were examined on a metamaterial sensor, resulting in 81% of precision with high selectivity (4.5 times), and three cycles of consecutive use. Overall, our micro-reactor stood out for its high productivity (48-288 times improvement in assay-time and 2 times improvement in reagent volume), enabling to produce 1.4-1.5 times more MIPs at one-single step, and continuous production compared to conventional strategy.

Dual-Functional Monomer MIPs and Their Comparison to Mono-Functional Monomer MIPs for SPE and as Sensors

A molecularly imprinted polymer (MIP) is a synthetic polymer that has characteristics such as natural receptors which are able to interact and bind to a specific molecule that is used as a template in the MIP polymerization process. MIPs have been widely developed because of the need for more selective, effective, and efficient methods for sample preparation, identification, isolation, and separation. The MIP compositions consist of a template, monomer, crosslinker, initiator, and porogenic solvent. Generally, MIPs are only synthesized using one type of monomer (mono-functional monomer); however, along with the development of MIPs, MIPs began to be synthesized using two types of monomers to improve the performance of MIPs. MIPs used for identification, separation, and molecular analysis have the most applications in solid-phase extraction (SPE) and as biochemical sensors. Until now, no review article has discussed the various studies carried out in recent years in relation to the synthesis of dual-functional monomer MIPs. This review is necessary, as an improvement in the performance of MIPs still needs to be explored, and a dual-functional monomer strategy is one way of overcoming the current performance limitations. In this review article, we discuss the techniques commonly used in the synthesis of dual-functional monomer MIPs, and the use of dual-functional monomer MIPs as sorbents in the MI-SPE method and as detection elements in biochemical sensors. The application of dual-functional monomer MIPs showed better selectivity and adsorption capacity in these areas when compared to mono-functional monomer MIPs. However, the combination of functional monomers must be selected properly, in order to achieve an effective synergistic effect and produce the ideal MIP characteristics. Therefore, studies regarding the synergistic effect of the MIP combination still need to be carried out to obtain MIPs with superior characteristics.

Single-drop microextraction technique for the determination of antibiotics in environmental water

Growing concerns related to antibiotic residues in environmental water have encouraged the development of rapid, sensitive, and accurate analytical methods. Single-drop microextraction has been recognized as an efficient approach for the isolation and preconcentration of several analytes from a complex sample matrix. Thus, single-drop microextraction techniques are cost-effective and less harmful to the environment, subscribing to green analytical chemistry principles. Herein, an overview and the current advances in single-drop microextraction for the determination of antibiotics in environmental water are presented were included. In particular, two main approaches used to perform single-drop microextraction (direct immersion-single-drop microextraction and headspace-single-drop microextraction) are reviewed. Furthermore, the impressive analytical features and future perspectives of single-drop microextraction are discussed in this review. This article is protected by copyright. All rights reserved.

Eco-friendly fabrication of a magnetic dual-template molecularly imprinted polymer for the selective enrichment of organophosphorus pesticides for fruits and vegetables

A magnetic dual-template molecularly imprinted polymer (DMIP) was successfully prepared in an aqueous medium and used as a sorbent for the selective extraction of organophosphorus pesticides prior to analysis by high-performance liquid chromatography (HPLC). The binding properties and selectivity of DMIP toward organophosphorus were evaluated and compared with those of a non-imprinted polymer. The established magnetic dispersive solid-phase extraction (MDSPE) method using DMIP exhibited fast enrichment of the target analytes within 60 s for adsorption and 30 s for desorption. Good linearities in the range of 0.5-2000 μg L^-1 with coefficients of determination (R²) greater than 0.9930 were observed. The method provides low limits of detection of 0.062-0.195 μg L^-1 and limits of quantification of 0.210-0.640 μg L^-1 with relative standard deviations of less than 9.5% for intra- and inter-day analyses. The enrichment factors ranged from 464 to 621. Satisfactory recoveries ranged from 81.3 to 110.0% with relative standard deviations below 11%.

Synthesis of molecularly imprinted polymers for extraction of fluoroquinolones in environmental, food and biological samples

In recent years, fluoroquinolones have been found present in important water resources and food sources which compromises the food quality and availability, thereby, causing risks to the consumer. Despite the recent advancement in the development of analytical instrumentation for routine monitoring of fluoroquinolones in water, food, and biological samples, sample pre-treatment is still a major bottleneck of the analytical methods. Therefore, fast, selective, sensitive, and cost-effective sample preparation methods prior to instrumental analysis for fluoroquinolones residues in environmental, food and biological samples are increasingly important. Solid-phase extraction using different adsorbents is one of the most widely used pre-concentration/clean-up techniques for analysis of fluoroquinolones. Molecularly imprinted polymers (MIPs) serve as excellent effective adsorbent materials for selective extraction, separation, clean-up and preconcentration of various pollutants in different complex matrices. Therefore, synthesis of MIPs remains crucial for their applications in sample preparation as this offers much-needed selectivity in the extraction of compounds in complex samples. In this study, the progress made in the synthesis of MIPs for fluoroquinolones and their applications in water, food and biological samples were reviewed. The present review discusses the selection of all the elements of molecular imprinting for fluoroquinolones, polymerization processes and molecular recognition mechanisms. In conclusion, the related challenges and gaps are given to offer ideas for future research focussing on MIPs for fluoroquinolones.

Co-precipitation polymerization of dual functional monomers and polystyrene-co-divinylbenzene for ciprofloxacin imprinted polymer preparation

Novel ciprofloxacin composite imprinted materials are synthesized by using co-precipitation polymerization of dual functional monomers (methacrylic acid and 2-vinylpyridine) and polystyrene-co-divinylbenzene. The intermolecular interactions between monomers and template are evaluated by molecular modeling analysis. The physicochemical properties of the obtained polymers are characterized using FT-IR, TGA, and SEM. Batch adsorption experiments are used to investigate adsorption properties (kinetic, pH, and isotherm). These polymers are employed to prepare the solid phase extraction cartridges, and their extraction performances are analyzed by the HPLC-UV method. DFT calculations indicate that hydrogen bonding and π−π stacking are the driving forces for the formation of selective rebinding sites. The obtained polymers exhibit excellent adsorption properties, including fast kinetics and high adsorption capacity (up to 10.28 mg g⁻¹) with an imprinted factor of 2.55. The Scatchard analysis indicates the presence of specific high-affinity adsorption sites on the imprinted polymer. These absorbents are employed to extract CIP in river water with recoveries in the range of 65.97–119.26% and the relative standard deviation of 3.59–14.01%. Furthermore, the used cartridges could be reused at least eight times without decreasing their initial adsorption capacity.

Ciprofloxacin imprinted polymers were prepared using co-precipitation polymerization of methacrylic acid, 2-vinylpyridine and polystyrene-co-divinylbenzene.

Multi-templates surface molecularly imprinted polymer for simultaneous and rapid determination of sulfonamides and quinolones in water: effect of carbon-carbon double bond

In this work, the effect of a carrier modified with a carbon-carbon double bond (C=C) on preparing multi-templates surface molecularly imprinted polymer MIP (C=C@MIP) for simultaneous detection of sulfonamides and quinolones was investigated. The results showed that the adsorption capacities of the C=C@MIP were obviously higher than those of MIP, which is the carrier without modified C=C, suggesting that C=C played a key role in preparing MIP with higher adsorption capacities. Then, C=C@MIP was used as adsorbents for solid-phase extraction (SPE) and coupled with high-performance liquid chromatography (HPLC) for the simultaneous determination of sulfonamides and quinolones in water. The method showed excellent applicability, with the adsorption capacities of 19.92, 16.38, 12.92, 18.37, 14.49, 12.01, 16.98, 23.33, and 14.29 mg/g for SDZ, STZ, SMZ, SMX, SDM, ENRO, OFL, LOME, and GATI, respectively. The spiked recoveries and relative standard deviations (RSDs) of sulfonamides and quinolones using C=C@MIP were 81.59-100.7 % and 3.75-7.37 %, respectively. The limits of detection (LODs) for SDZ, STZ, SMZ, SMX, SDM, ENRO, OFL, LOME, and GATI were 0.013, 0.012, 0.012, 0.013, 0.014, 0.012, 0.013, 0.015, and 0.015 μg/L, respectively.

Synergetic Effect of Dual Functional Monomers in Molecularly Imprinted Polymer Preparation for Selective Solid Phase Extraction of Ciprofloxacin

BACKGROUND

Ciprofloxacin (CIP), an important broad-spectrum fluoroquinolone antibiotic, was often used as a template molecule for the preparation of imprinted materials. In this study, methacrylic acid and 2-vinylpyridine were employed for the first time as dual functional monomers for synthesizing ciprofloxacin imprinted polymers.

METHODS

The chemical and physicochemical properties of synthesized polymers were characterized using Fourier transform-infrared spectroscopy, thermogravimetric analysis-differential scanning calorimetry, scanning electron microscopy, and nitrogen adsorption-desorption isotherm. The adsorption properties of ciprofloxacin onto synthesized polymers were determined by batch experiments. The extraction performances were studied using the solid phase extraction and HPLC-UV method.

RESULTS

The molecularly imprinted polymer synthesized with dual functional monomers showed a higher adsorption capacity and selectivity toward the template molecule. The adsorbed amounts of ciprofloxacin onto the imprinted and non-imprinted polymer were 2.40 and 1.45 mg g-1, respectively. Furthermore, the imprinted polymers were employed as a selective adsorbent for the solid phase extraction of ciprofloxacin in aqueous solutions with the recovery of 105% and relative standard deviation of 7.9%. This work provides an alternative approach for designing a new adsorbent with high adsorption capacity and good extraction performance for highly polar template molecules.

Sensitive 'two-steps' competitive assay for gonadotropin-releasing hormone detection via SPR biosensing and polynorepinephrine-based molecularly imprinted polymer

The work reports an innovative bioassay for the detection of gonadorelin in urine, a gonadotropin-releasing hormone agonist widely used in fertility medicine and to treat hormonal dysfunctions. Gonadorelin is also a synthetic hormone listed by the World Anti-Doping Agency (WADA) and of interest in anti-doping controls. The main novelty relies on the development of a biocompatible, stable, and low-cost biomimetic receptor alternative to classic antibodies. Starting from norepinephrine monomer, a highly selective and sensitive molecularly imprinted polymer (MIP) was developed and optimized for optical real-time and label-free SPR biosensing. The selectivity has been addressed by testing a series of peptides, from high to low similarity, both in terms of molecular weight and primary sequence. Due to the very low molecular weight of gonadorelin (1182 Da), a 'two-steps' competitive assay was developed. Particular attention has been paid to the design of the competitor and its binding affinity constant towards the MIP, being a key step for the success of the competitive strategy. The SPR assay was first optimized in standard conditions and finally applied to untreated urine samples, achieving the sensitivity required by WADA guidelines. The MIP, tested in parallel with a monoclonal antibody, gave comparable results in terms of affinity constants and selectivity towards possible interfering analytes. However, the biomimetic receptor appears clearly superior in terms of sensitivity and reproducibility. This, together with its preparation simplicity, the extremely low-cost of the monomer and its reusability for hundreds of measurements, make polynorepinephrine-based MIPs powerful rivals to immune-based approaches in the near future for similar applications.

Eco-friendly ionic liquid imprinted polymer based on a green synthesis strategy for highly selective adsorption tylosin in animal muscle samples

A novel eco-friendly molecularly imprinted polymer (MIP) was proposed as solid-phase extraction (SPE) adsorbent to selective adsorption tylosin (TYL) in animal muscle samples. The MIP was synthesized in aqueous by using 1,4-butanediyl-3,3-bis-1-vinyl imidazolium chloride and 2-acrylamide-2-methylpropanesulfonic acid as bifunctional monomer. The obtained MIP had excellent selectivity towards TYL in water, and the maximum binding capacity can reach 123.45 mg g^-1. Combined with high-performance liquid chromatography, the presented MIP can be used as SPE sorbent to recognize and detect TYL in the range of 0.008 to 0.6 mg L^-1 (R² = 0.9995). The limit of detection and limit of quantification were 0.003 mg L^-1 and 0.008 mg L^-1, and the intraday and interday precision were 1.05% and 3.36%, respectively. Under the optimal condition, the established MIP-SPE-HPLC method was successfully applied to separate and determine trace TYL in chicken, pork, and beef samples with satisfactory recoveries ranged from 94.0 to 106.3%, and the MIP-SPE cartridge can be cycled at least 20 times. This study implies a promising green MIP-SPE-HPLC method for highly selective adsorption and analysis trace TYL in complex matrices.

Low-cost disposable Poly(ethyleneimine)-Functionalized Carbon Nanofibers Coated Cellulose Paper as efficient solid phase extraction sorbent material for the extraction of Parahydroxybenzoates from environmental waters

Parahydroxybenzoates (parabens) are considered as emerging environmental contaminants because of their extensive usage in our daily life products, causing parabens contamination into environmental water systems and lead to toxic effects on environmental health. This study describes a greener extraction method using a new cationic polymer poly (ethyleneimine) functionalized acid-treated carbon nanofibers (PEI-CNFs) coated cellulose paper (CP) as solid-phase extraction (SPE) sorbent material for the extraction of parabens from environmental water samples. The fabrication of PEI-CNFs modified CP was confirmed using field-emission scanning electron microscope, transmission electron microscopy, and fourier-transformer infrared spectroscopy techniques. Various factors affecting the adsorption and desorption of parabens on PEI-CNFs@CP and its extraction efficiencies were studied using HPLC-UV analysis. Under the optimal experimental conditions, maximum extraction efficiencies were achieved for four target parabens, and PEI-CNFs@CP/HPLC-UV method exhibited excellent linearities ranged from 0.5-50 ng mL^-1 with regression coefficient values were between 0.9952-0.9970. The presented method showed good sensitivity with quantification limits between 0.5-0.75 ng mL^-1 and detection limits between 0.1-0.25 ng mL^-1. The developed technique was applied for the real sample analysis (river, lake, domestic sewage water, and drinking tap water). The spiked recovery revealed good recoveries between 86.8-116.0% with RSD less than 8.8% for all the water samples. These results proved that it a simple, fast, efficient, low-cost, and eco-friendly method for the extraction and determination of parabens in environmental water samples and can be applied as a routine analytical tool in environmental monitoring and quality control laboratories.

Efficient removal of norfloxacin in water using magnetic molecularly imprinted polymer

Effective and practical materials are important for the pollution control in the environment. A novel magnetic molecularly imprinted polymer (CoFe₂O₄@TiO₂-MMIP) was prepared based on the surface molecular imprinting technology combined with photocatalytic degradation and magnetic separation. The adsorption rate constant and maximum adsorption capacity of CoFe₂O₄@TiO₂-MMIP are 0.21 g mg^-1 min^-1 and 14.26 mg g^-1, respectively. The effects of experimental factors on the adsorption properties of the magnetic molecularly imprinted polymer were investigated. CoFe₂O₄@TiO₂-MMIP had selective adsorption ability towards fluoroquinolones. The adsorption efficiency was closely related to the molecular structure, molecular weight, polarity and functional groups of the target contaminant and the removal efficiency of norfloxacin was affected by another substance obviously in binary adsorption system. The adsorption-photocatalytic recycling experiment verified that CoFe₂O₄@TiO₂-MMIP could simultaneously complete the degradation of pollutants and in-situ regeneration, indicating good reusability. This material with selective adsorption and photocatalytic regeneration would have substantial attraction for application in the removal of fluoroquinolones.

Effects of prepolymerization on surface molecularly imprinted polymer for rapid separation and analysis of sulfonamides in water

This work systematically investigated the effects of prepolymerization on the property of multi-templates surface molecularly imprinted polymer (MIP), which was utilized to quickly and simultaneously separate and detect six sulfonamides (sulfadiazine, sulfathiazole, sulfamerazine, sulfamethazine, sulfamethoxazole and sulfadoxine) in real waters. The MIPs were prepared using the six sulfonamides as the templates, mesoporous silica supported onto the surface of magnetic graphene oxide as the carrier and 4-vinylbenzoic as the functional monomer, with and without prepolymerization of templates with functional monomer. The preparation and adsorption conditions were optimized. It was found that the adsorption capacities of the selected six sulfonamides on the MIP (pre) prepared with prepolymerization were apparently higher than those on the MIP (no pre) synthesized without prepolymerization. Subsequently, the MIPs were utilized as adsorbents for SPE of these sulfonamides, and coupled with high performance liquid chromatography (HPLC) for the determination of sulfonamides. The developed analytical method showed outstanding applicability for the detection of trace sulfonamides in real water samples. The spiked recoveries and relative standard deviations (RSDs) of the six sulfonamides using MIP (no pre) and MIP (pre) were 73.34-99.43% and 87.37-102.34%, 2.28-7.77% and 3.18-6.49%, respectively.