Synthesis of Molecularly Imprinted Polymer via Emulsion Polymerization for Application in Solanesol Separation

Design and synthesis of S-citalopram-imprinted polymeric sorbent: Characterization and application in enantioselective separation

The current work describes the efficient creation and employment of a new S-citalopram selective polymeric sorbent, made from poly(divinylbenzene-maleic anhydride-styrene). The process began by using suspension polymerization technique in the synthesis of poly(styrene-maleic anhydride-divinylbenzene) microparticles. These were then modified with ethylenediamine, developing an amido-succinic acid-based polymer derivative. The S-citalopram, a cationic molecule, was loaded onto these developed anionic polymer particles. Subsequently, the particles were post-crosslinked using glyoxal, which reacts with the amino group residues of ethylenediamine. S-citalopram was extracted from this matrix using an acidic solution, which also left behind stereo-selective cavities in the S-citalopram imprinted polymer, allowing for the selective re-adsorption of S-citalopram. The attributes of the polymer were examined through methods such as 13C NMR, FTIR, thermogravemetric and elemental analyses. SEM was used to observe the shapes and structures of the particles. The imprinted polymers demonstrated a significant ability to adsorb S-citalopram, achieving a capacity of 878 mmol/g at a preferred pH level of 8. It proved efficient in separating enantiomers of (±)-citalopram via column methods, achieving an enantiomeric purity of 97 % for R-citalopram upon introduction and 92 % for S-citalopram upon release.

Molecularly imprinted polymer-based electrochemical sensors for monitoring the persistent organic pollutants chlorophenols

Because of the serious risks they pose to the environment and public health, chlorophenols (CPs), a typical class of the most persistent organic pollutants, have drawn increasing attention. Monitoring CPs effectively has become a pressing and difficult problem. The rapidly increasing need for onsite and real-time CP detection has led to the consideration of electrochemical sensing as a workable solution. Molecularly imprinted polymer (MIP)-based electrochemical sensing has emerged as a promising area for environmental monitoring in response to this analytical problem. MIPs, in conjunction with miniature electrochemical transducers, provide the opportunity to detect target analytes in situ. These devices have the advantages of great chemical and physical stability, cheap production costs, good selectivity, and quick response times. Most studies suggest that these sensors use nanoparticles to improve their analytical properties, especially sensitivity. Furthermore, these sensors have successfully used real water samples without the need for time-consuming pretreatment procedures. This article provides an overview of electrochemical MIP-based sensors reported to detect CPs in water samples. To obtain the highest sensitivity, special consideration is given to the fabrication of the sensors, which includes the use of various functional monomers, sensing platforms, and materials. Several other parameters are also discussed, including the linear concentration range, limit of detection, and the types of water samples that were examined.

An Overview on Recent Advances in Biomimetic Sensors for the Detection of Perfluoroalkyl Substances

Per- and polyfluoroalkyl substances (PFAS) are a class of materials that have been widely used in the industrial production of a wide range of products. After decades of bioaccumulation in the environment, research has demonstrated that these compounds are toxic and potentially carcinogenic. Therefore, it is essential to map the extent of the problem to be able to remediate it properly in the next few decades. Current state-of-the-art detection platforms, however, are lab based and therefore too expensive and time-consuming for routine screening. Traditional biosensor tests based on, e.g., lateral flow assays may struggle with the low regulatory levels of PFAS (ng/mL), the complexity of environmental matrices and the presence of coexisting chemicals. Therefore, a lot of research effort has been directed towards the development of biomimetic receptors and their implementation into handheld, low-cost sensors. Numerous research groups have developed PFAS sensors based on molecularly imprinted polymers (MIPs), metal-organic frameworks (MOFs) or aptamers. In order to transform these research efforts into tangible devices and implement them into environmental applications, it is necessary to provide an overview of these research efforts. This review aims to provide this overview and critically compare several technologies to each other to provide a recommendation for the direction of future research efforts focused on the development of the next generation of biomimetic PFAS sensors.

Synthesis of a New Molecularly Imprinted Polymer and Optimisation of Phenylglyoxylic Acid Extraction from Human Urine Samples Using a Central Composite Design within the Response Surface Methodology

Styrene, a chemical widely used in various industries, undergoes metabolic breakdown in the human body, resulting in the production of phenylglyoxylic acid (PGA). A novel molecularly imprinted polymer (MIP) was synthesised for selective extraction and enrichment of PGA in urine samples prior to high-performance liquid chromatography. The MIP employed in this research was a 4-vinylpyridine molecularly imprinted polymer (4-VPMIP) prepared via mass polymerisation using a noncovalent method. The structural and morphological characteristics of the molecularly imprinted polymers (MIPs) and non-imprinted polymers (NIPs) were evaluated using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The efficiency of the molecularly imprinted solid-phase extraction (MISPE) process was optimised by investigating critical variables such as sample pH, sorbent mass, sample flow rate, and volume of the elution solvent. A central composite design (CCD) within the response surface methodology was utilised to develop separate models for the adsorption and desorption steps. Analysis of variance (ANOVA) confirmed the excellent fit of the experimental data to the proposed response models. Under the optimised conditions, the molecularly imprinted polymers exhibited a higher degree of selectivity and affinity for PGA, with a relative selectivity coefficient (α) of 2.79 against hippuric acid. The limits of detection (LOD) and quantification (LOQ) for PGA were determined to be 0.5 mg/L and 1.6 mg/L, respectively. The recoveries of PGA ranged from 97.32% to 99.06%, with a relative standard deviation (RSD) lower than 4.6%. Furthermore, MIP(4VP)SPE demonstrated the potential for recycling up to three times without significant loss in analyte recovery.

Synthesis and Characterization of a New Molecularly Imprinted Polymer for Selective Extraction of Mandelic Acid Metabolite from Human Urine as a Biomarker of Environmental and Occupational Exposures to Styrene

4-Vinylpyridine molecularly imprinted polymer (4-VPMIP) microparticles for mandelic acid (MA) metabolite as a major biomarker of exposure to styrene (S) were synthesized by bulk polymerization with a noncovalent approach. A common mole ratio of 1:4:20 (i.e., metabolite template: functional monomer: cross-linking agent, respectively) was applied to allow the selective solid-phase extraction of MA in a urine sample followed by high-performance liquid chromatography-diode array detection (HPLC-DAD). In this research, the 4-VPMIP components were carefully selected: MA was used as a template (T), 4-Vinylpyridine (4-VP) as a functional monomer (FM), ethylene glycol dimethacrylate (EGDMA) as a cross-linker (XL), and azobisisobutyronitrile (AIBN) as an initiator (I) and acetonitrile (ACN) as a porogenic solvent. Non-imprinted polymer (NIP) which serves as a "control" was also synthesized simultaneously under the same condition without the addition of MA molecules. Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were used to characterize the imprinted and nonimprinted polymer to explain the structural and morphological characteristics of the 4-VPMIP and surface NIP. The results obtained from SEM depicted that the polymers were irregularly shaped microparticles. Moreover, MIPs surfaces had cavities and were rougher than NIP. In addition, all particle sizes were less than 40 µm in diameter. The IR spectra of 4-VPMIPs before washing MA were a little different from NIP, while 4-VPMIP after elution had a spectrum that was almost identical to the NIP spectrum. The adsorption kinetics, isotherms, competitive adsorption, and reusability of 4-VPMIP were investigated. 4-VPMIP showed good recognition selectivity as well as enrichment and separation abilities for MA in the extract of human urine with satisfactory recoveries. The results obtained in this research imply that 4-VPMIP might be used as a sorbent for MA solid-phase extraction (MISPE), for the exclusive extraction of MA in human urine.

Application of molecular imprinting technology based on new nanomaterials in adsorption and detection of fluoroquinolones

Irrational use of fluoroquinolones (FQs) can lead to allergic reactions, adverse reactions to the heart and damage of the liver; thus, it is of great significance to establish rapid, sensitive and accurate detection methods for FQs. Molecularly imprinted polymers (MIPs) with specific structures synthesized by molecular imprinting technology (MIT) are widely used for the detection of FQs due to their high specificity, high sensitivity and stable performance. Recently, new functional nanomaterials with different morphologies and sizes, which can provide rich sites for surface chemical reactions, have attracted more and more attention of the researchers. Thus, the application status and development prospects of MIT based on new nanomaterials in the adsorption and detection of FQs were summarized in this study, providing a theoretical basis and technical guarantee for the development of new and efficient food safety analysis strategies based on MIPs.

Thermal Pyocyanin Sensor Based on Molecularly Imprinted Polymers for the Indirect Detection of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a ubiquitous multi-drug-resistant bacterium, capable of causing serious illnesses and infections. This research focuses on the development of a thermal sensor for the indirect detection of P. aeruginosa infection using molecularly imprinted polymers (MIPs). This was achieved by developing MIPs for the detection of pyocyanin, the main toxin secreted by P. aeruginosa. To this end, phenazine was used as a dummy template, evaluating several polymeric compositions to achieve a selective MIP for pyocyanin recognition. The sensitivity of the synthesized MIPs was investigated by UV-vis analysis, with the best composition having a maximum rebinding capacity of 30 μmol g^-1 and an imprinting factor (IF) of 1.59. Subsequently, the MIP particles were immobilized onto planar aluminum chips using an adhesive layer, to perform thermal resistance measurements at clinically relevant concentrations of pyocyanin (1.4-9.8 μM), achieving a limit of detection (LoD) of 0.347 ± 0.027 μM. The selectivity of the sensor was also scrutinized by subjecting the receptor to potential interferents. Furthermore, the rebinding was demonstrated in King's A medium, highlighting the potential of the sensor for the indirect detection of P. aeruginosa in complex fluids. The research culminates in the demonstration of the MIP-based sensor's applicability for clinical diagnosis. To achieve this goal, an experiment was performed in which the sensor was exposed to pyocyanin-spiked saliva samples, achieving a limit of detection of 0.569 ± 0.063 μM and demonstrating that this technology is suitable to detect the presence of the toxin even at the very first stage of its production.

Biodegradable Mulching Films Based on Polycaprolactone and Its Porous Structure Construction

Polycaprolactone (PCL) is one of the promising linear aliphatic polyesters which can be used as mulching film. Although it has suitable glass transition temperature and good biodegradability, further practical applications are restricted by the limited temperature-increasing and moisturizing properties. The rational design of the PCL structure is a good strategy to enhance the related properties. In this study, thermally-induced phase separation (TIPS) was introduced to fabricate a PCL nanoporous thin film. The introduction of a nanoporous structure on the PCL surface (np-PCL) exhibited enhanced temperature-increasing and moisturizing properties when used as mulch film. In detail, the average soil temperature of np-PCL was increased to 17.81 °C, when compared with common PCL of 17.42 °C and PBAT of 17.50 °C, and approaches to PE of 18.02 °C. In terms of water vapor transmission rate, the value for np-PCL is 637 gm^-2day^-1, which was much less than the common PCL of 786 and PBAT of 890 gm^-2day^-1. As a result, the weed biomass under the np-PCL was suppressed to be 0.35 kg m^-2, almost half of the common PCL and PBAT. In addition, the np-PCL shows good thermal stability with an onset decomposition temperature of 295 °C. The degradation mechanism and rate of the np-PCL in different pH environments were also studied to explore the influence of nanoporous structure. This work highlights the importance of the nanoporous structure in PCL to enhance the temperature-increasing and moisturizing properties of PCL-based biodegradable mulching film.

Progress and challenges in sensing of mycotoxins using molecularly imprinted polymers

Mycotoxin is toxic secondary metabolite formed by certain filamentous fungi. This toxic compound can enter the food chain through contamination of food (e.g., by colonization of toxigenic fungi on food). In light of the growing concerns on the health hazards posed by mycotoxins, it is desirable to develop reliable analytical tools for their detection in food products in both sensitive and efficient manner. For this purpose, the potential utility of molecularly imprinted polymers (MIPs) has been explored due to their meritful properties (e.g., large number of tailor-made binding sites, sensitive template molecules, high recognition specificity, and structure predictability). This review addresses the recent advances in the application of MIPs toward the sensing of various mycotoxins (e.g., aflatoxins and patulin) along with their fabrication strategies. Then, performance evaluation is made for various types of MIP- and non-MIP-based sensing platforms built for the listed target mycotoxins in terms of quality assurance such as limit of detection (LOD). Further, the present challenges in the MIP-based sensing application of mycotoxins are discussed along with the future outlook in this research field.

Magnetic Molecularly Imprinted Polymers: An Update on Their Use in the Separation of Active Compounds from Natural Products

During the last few years, separation techniques using molecularly imprinted polymers (MIPs) have been developed, making breakthroughs using magnetic properties. Compared to conventional MIPs, magnetic molecularly imprinted polymers (MMIPs) have advantages in sample pretreatment due to their high specificity and selectivity towards analytes as a result of their larger specific surface areas and highly accessible specific binding sites. The techniques of isolation of active compounds from natural products usually require very long process times and low compound yields. When MMIPs are used in sample separation as Solid Phase Extraction (SPE) sorbents, the MMIPs are introduced into the dissolved sample and spread evenly, and they form bonds between the analyte and the MMIPs, which are then separated from the sample matrix using an external magnetic field. This process of separating analytes from the sample matrix makes the separation technique with MMIPs very simple and easy. This review discusses how to synthesize MMIPs, which factors must be considered in their synthesis, and their application in the separation of active compounds from natural products. MMIPs with magnetic core-shells made by co-precipitation can be a good choice for further development due to the high synthesis yield. Further optimization of the factors affecting the size and distribution of magnetic core-shell particles can obtain higher synthesis yields of MMIPs with higher adsorption capacity and selectivity. Thus, they can isolate target compounds from natural plants in high yields and purity.

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.

The Evolution of Molecular Recognition: From Antibodies to Molecularly Imprinted Polymers (MIPs) as Artificial Counterpart

Molecular recognition is a useful property shared by various molecules, such as antibodies, aptamers and molecularly imprinted polymers (MIPs). It allows these molecules to be potentially involved in many applications including biological and pharmaceutical research, diagnostics, theranostics, therapy and drug delivery. Antibodies, naturally produced by plasma cells, have been exploited for this purpose, but they present noticeable drawbacks, above all production cost and time. Therefore, several research studies for similar applications have been carried out about MIPs and the main studies are reported in this review. MIPs, indeed, are more versatile and cost-effective than conventional antibodies, but the lack of toxicity studies and their scarce use for practical applications, make it that further investigations on this kind of molecules need to be conducted.

Development of a microfluidic dispensing device for multivariate data acquisition and application in molecularly imprinting hydrogel preparation

Molecularly imprinted polymer (MIP) is the superior material with molecular recognition ability that applies to various applications. In order to get high specificity recognition for target molecules, selecting polymerization conditions,...

Molecularly Imprinted Polymers in Diagnostics: Accessing Analytes in Biofluids

Bio-applied molecularly imprinted polymers (MIPs) are biomimetic materials with tailor-made synthetic recognition sites, mimicking biological counterparts known for their sensitive and selective analyte detection. MIPs, specifically designed for biomarker analysis...

Factors Affecting Preparation of Molecularly Imprinted Polymer and Methods on Finding Template-Monomer Interaction as the Key of Selective Properties of the Materials

Molecular imprinting is a technique for creating artificial recognition sites on polymer matrices that complement the template in terms of size, shape, and spatial arrangement of functional groups. The main advantage of Molecularly Imprinted Polymers (MIP) as the polymer for use with a molecular imprinting technique is that they have high selectivity and affinity for the target molecules used in the molding process. The components of a Molecularly Imprinted Polymer are template, functional monomer, cross-linker, solvent, and initiator. Many things determine the success of a Molecularly Imprinted Polymer, but the Molecularly Imprinted Polymer component and the interaction between template-monomers are the most critical factors. This review will discuss how to find the interaction between template and monomer in Molecularly Imprinted Polymer before polymerization and after polymerization and choose the suitable component for MIP development. Computer simulation, UV-Vis spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Proton-Nuclear Magnetic Resonance (¹H-NMR) are generally used to determine the type and strength of intermolecular interaction on pre-polymerization stage. In turn, Suspended State Saturation Transfer Difference High Resolution/Magic Angle Spinning (STD HR/MAS) NMR, Raman Spectroscopy, and Surface-Enhanced Raman Scattering (SERS) and Fluorescence Spectroscopy are used to detect chemical interaction after polymerization. Hydrogen bonding is the type of interaction that is becoming a focus to find on all methods as this interaction strongly contributes to the affinity of molecularly imprinted polymers (MIPs).

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.

Preparation and adsorption properties of Ni(ii) ion-imprinted polymers based on synthesized novel functional monomer

In this study, a novel functional monomer N-(1-(2,4-difluorophenyl)-2-(1H-1,2,4-triazol-1-yl)ethyl)acrylamide (NDTEA) was designed and synthesized, and was used to prepare Ni(ii) ion-imprinted polymers (Ni(ii)-IIPs). Sixteen kinds of Ni(ii)-IIP (Ni(ii)-IIP1–16) and corresponding non-imprinted polymers (NIP1–16) were prepared by precipitation polymerization method. After optimized condition experiment, Ni(ii)-IIP5 possessed maximum adsorption capacity and better imprinting factor under optimal experimental conditions which indicated by equilibrium adsorption experiments. The morphology and structural characteristics of Ni(ii)-IIP5 were characterized by scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET). The adsorption selectivity of Ni(ii)-IIP5 was analyzed by ICP-OES, and the results showed that Ni(ii)-IIP5 had favorable selectivity recognition ability for Ni(ii) when Cu(ii), Co(ii), and Cd(ii) are used as competitive ions. The kinetic experiment indicated that the performance of Ni(ii) adsorption on the surface of Ni(ii)-IIP5 obeyed the pseudo-first-order model, and adsorption equilibrium was attained after 15 min. Isothermal adsorption process fitted to Langmuir and Freundlich isothermal adsorption models, simultaneously. The results showed that Ni(ii)-IIP5 prepared by using a new functional monomer had better permeation selectivity and higher affinity for Ni(ii), which also verified the rationality of the functional monomer design. At the same time, it also provided a broad application prospect for removal of Ni(ii) in complex samples.