Innovative Methods of Synthesis and Characterization for Molecularly Imprinted Polymers

The characterization of these molecularly imprinted polymers is essential to understanding their binding dynamics and structural properties. Through the analysis of the current research, it is found that there are overlaps in the methods used by scholars. The Langmuir equation is frequently applied to model the adsorption isotherms of MIPs, providing critical insight into the capacity and affinity of the binding sites. Infrared Spectroscopy (IR) plays a crucial role in identifying the functional groups involved in the imprinting process and confirming the successful formation of specific binding sites. UV-visible spectrophotometry is employed to monitor the absorption characteristics of the polymers, offering data on the interactions between the template molecules and the polymer matrix. Transmission Electron Microscopy (TEM) provides detailed visualization of the internal structure of MIPs at the nanoscale, revealing the morphology and size of the imprinted cavities. Thermogravimetric Analysis (TGA) assesses the thermal stability and composition of the polymers, identifying decomposition patterns that are indicative of the material’s robustness under different conditions. Finally, the Laser Particle Size Analyzer is used to measure the size distribution of the polymer particles, which is critical for determining the uniformity and efficiency of the imprinting process. The six characterization methods discussed in this paper provide a comprehensive understanding of MIP, and it is hoped that in the future, more optimized design solutions will emerge and their applications in various fields will be enhanced.

Preparation of high selective molecularly imprinted polymers for tetracycline by precipitation polymerization

High selective molecularly imprinted polymers （MIPs） for tetracycline have been prepared by precipitation polymerization. Effects of monomer and solvent, the ratio of monomer and template and the characterization of the polymer were investigated by frontal chromatography and selectivity experiment. The results clearly indicated that the polymer, which had the highest molecular recognition abilities for tetracycline antibiotics, had been received.

Fluorescent competitive assay for melamine using dummy molecularly imprinted polymers as antibody mimics

A fluorescent competitive assay for melamine was first developed utilizing dummy molecularly imprinted polymers（DMIPs） as artificial antibodies. This method is based on the competition between fluorescent substances and the unlabeled analyte for binding sites in synthesized DMIPs and the decreased binding of fluorescent substances to DMIPs due to increased concentrations of melamine in the solutions. DMIPs for melamine were synthesized under a hot water bath in the presence of the initiator azobisisobutyronitrile（AIBN） using 2,4-diamino-6-methyl-1,3,5-triazine（DAMT） as a dummy template, methacrylic acid（MAA） as a functional monomer, and ethylene glycol dimethacrylate（EGDMA） as a crosslinking agent. The adsorption capacity and selectivity of DMIPs for melamine were evaluated by the isothermal adsorption curve and Scatchard analysis. The evaluation results showed that the synthesized DMIPs had specific recognition sites for melamine and the maximum adsorption amount was 1 066.33 μg g^（-1）. Later, 5-（4,6-d ichlorotriazinyl） amino fluorescein（DTAF） with a triazine ring, which s lightly resembles m elamine, w as selected as the fluorescent substance. The fluorescent competitive assay using DMIPs as t he antibody mimics was finally established by selecting and optimizing the reaction solvents, DMIPs amount, DTAF concentration, and incubation time. The optimal detection system showed a linear response w ithin range of 0.05-40 mg L^（-1） and the limit of detection（LOD） was 1.23 μg L^（-1）. It was successfully applied to the detection of melamine in spiked milk samples wi th satisfactory recoveries（71.9 to 86.3%）. According to the comparative analysis, the result of optimized fluorescent competitive assay re vealed excellent agreement with the HPLC-MS/MS result for melamine.

Preparation of Magnetic Molecularly Imprinted Polymers for Selective Isolation and Determination of Kaempferol and Protoapigenone in Macrothelypteris torresiana

Novel uniform-sized magnetic molecularly imprinted polymers （MMIPs） were synthe- sized for selective recognition of active antitumor ingredients of kaempferol （KMF） and protoapi- genone （PA） in Macrothelypteris torresiana （M. torresiana） by surface molecular imprinting tech- nique in this study. Super paramagnetic core-sheU nanoparticles （γ-MPS-SiO2@Fe3O4） were used as seeds, KMF as template molecule, acrylamide （AM） as functional monomer, and N, N＇-methylene bisacrylamide （BisAM） as cross-linker. The prepared MMIPs were characterized by X-ray diffraction （XRD）, Fourier transform infrared spectrum fiT/R）, transmission electron microscopy （TEM） and thermo-gravimetric analysis （TGA）, respectively. The recognition capacity of MMIPs was 2.436 times of non-imprinted polymers. The adsorption results based on kinetics and isotherm analysis were in accordance with the pseudo-second-order model （R2=0.9980） and the Langmuir adsorption model （R2=0.9944）. The value of E （6.742 kJ/mol） calculated from the Dubinin-Radushkevich isotherm model suggested that the physical adsorption via hydrogen-bonding might be predominant. The Scatchard plot showed a single line （R2=0.9172） and demonstrated the homogeneous recognition sites on MMIPs for KMF. The magnetic solid phase extraction （MSPE） based on MMIPs as sorbent was established for fast and selective enrichment of KMF and its structural analogue PA from the crude extract of M. torresiana and then KMF and PA were detected by HPLC-UV. The established method showed good performance and satisfactory results for real sample analysis. It also showed the feasi- bility of MMIPs for selective recognition of active structural analogues from complex herbal extracts.

Molecularly Imprinted Polymers on Chloromethyl Polystyrene Resin Prepared via RAFT Polymerization

Surface molecularly imprinted polymers （SMIP） was prepared via the reversible addition-fragmentation chain transfer （RAFT） polymerization on the chloromethyl polystyrene resin （CPR） in the presence of the template D-phenylalanine. The structure of SMIP was characterized by FTIR and SEM. The adsorption behavior of D-phenylalanine of SMIP was preliminarily investigated.

STUDY ON THE NON-COVALENT INTERACTION OF APIGENIN MOLECULARLY IMPRINTED POLYMERS BY SPECTROMETRY

The non-covalent interaction between apigenin (API) and different functional monomers (α-methylacrylic acid (MAA), acrylamide (AM), 2-vinylpyridine (2-Vpy) and combined functional monomers (AM/2-Vpy)) was determined by UV spectrometry, and a series of apigenin molecularly imprinted polymers (API-MIPs) was synthesized with different functional monomers through molecular imprinting technology. The relationship between the non-covalent interaction of template/functional monomer and absorption of MIPs also was studied. The results showed that the order of the strength of the non-covalent interaction between API and different functional monomers in tetrahydrofuran (THF) is as follows: 2-Vpy> AM/2-Vpy>AM>MAA, which is positive correlation to the absorption capability of corresponding MIPs, and 2-Vpy is the optimum functional monomer among the used monomer for preparing API- MIPs.

Preparation of High Selective Molecularly Imprinted Polymers for (S)-4-Phenyl-2-oxazolidinone

（S）-4-Phenyl-2-oxazolidinone imprinted polymers were prepared by using methacrylic acid （MAA） as the functional monomer, and divinylbenzene （DVB） as crosslinker. The factors, which influence the selectivity of the polymers were explored. Effective separation was observed for racemic 4-phenyl-2-oxazolidinone in mobile phase of acetonitrile. The investigation of mobile phase suggested that the hydrogen bonds between template and functional monomer was a primary factor in chiral recognition, while the preparation of polymers implied that the л-л stacking interaction between template and crosslinker played a role in imprinting procedure.

RECENT ADVANCES IN THE PREPARATION OF MOLECULARLY IMPRINTED POLYMERS VIA CONTROLLED RADICAL POLYMERIZATION TECHNIQUES

Molecular imprinting technique is a simple and efficient method for the preparation of polymer materials (i.e., molecularly imprinted polymers, MIPs) with tailor-made recognition sites for certain target molecules. The resulting MIPs have proven to be versatile synthetic receptors due to their high specific recognition ability, favorable mechanical, thermal and chemical stability, and ease of preparation. Recent years have witnessed significant progress in the synthesis and applications of MIPs. This review focus on the recent developments and advances in the preparation of MIPs via various controlled radical polymerization techniques.

Synthesis and Solid Phase Extraction Performance Study of NNAL-specific Molecularly Imprinted Polymers Using Dummy Templates

Dummy molecularly imprinted polymers （DMIPs） for 4-（methylnitrosamino）-1-（3-pyridyl）-1-butanol （NNAL） were produced using three structural analogues as dummy template molecules. The chosen analogues were 4-（acetymethylamino）-1-（3-pyridyl）-butanol, 4- （methylamino）-1-（3-pyridyl）-1-butanol, and 1-（3-pyridyl）-1,4,-butanediol. The molecular recognition characteristics of the produced polymers were evaluated by X-ray photoelec- tron spectroscopy （XPS） and Fourier transform infrared spectroscopy （FT-IR）. Interactions between NNAL and methacrylic acid should be cooperative hydrogen bonds while the ni- trogen atom of the pyridine ring and the oxygen atom of the nitroso group in NNAL are two of the hydrogen-bond acceptors. It was further demonstrated that DMIP synthesized by 4-（acetymethylamino）-1-（3-pyridyl）-butanol had the best binding performance by XPS and FT-IR. Then dummy molecularly imprinted solid phase extraction （DMISPE） was developed for the determination of the analyte using the hit polymer as the sorbing material. Under optimal conditions, the recovery of NNAL dissolved in standard solution reached 93%. And the investigated polymer exhibited much higher binding of NNAL when nicotine was acted as the competitive molecule. Also the proposed method was applied to the measurement of NNAL spiked in blank urine samples with recoveries ranging from 87.2% to 101.2%.

Molecularly Imprinted Polymers for Selective Extraction of Crystal Violet from Natural Seawater coupled with HighPerformance Liquid Chromatographic Determination

Molecularly imprinted polymers （MIPs） were prepared by the bulk polymerization using crystal violet as the template molecule, and the methacrylic acid and ethylene glycol dimetheacrylate as functional monomer and cross-linker, respectively. Sys- tematic investigations of synthetic conditions were conducted. The surface morphology and recognition mechanism of the obtained polymers were studied using scanning electron microscope and spectrophotometric analysis. MIPs showed high atTmity to template molecule and were successfully applied as special solid-phase extraction sorbent for selective extraction of crystal violet from natural seawater. An off-line molecularly imprinted solid-phase extraction （MISPE） method followed by high-performance liquid chroma- tography with diodearray detection for the analysis of crystal violet was also established. MISPE columns have good recoveries for crystal violet standard solutions and good linearity was obtained over the concentration range of 0-200 ~tg L-1 （R2 〉 0.99）. Finally, two natural seawater samples were investigated. The recoveries of spiked seawater on the MISPE columns were from 44.47% to 62.34%, the relative standard deviation （n=3） being in the range of 2.89%-5.96%.

Theoretical Researches on the Self-assembly System of Molecularly Imprinted Polymers Formed via Phenobarbital and Acrylamide

For preparing the phenobarbital(PHN) molecularly imprinted polymers(MIPs) with higher adsorption and selectivity properties, we used the M062 X/6-31 g(d,p) method of density functional theory to predict the various properties of PHN-MIPs. Here PHN is as the imprinted molecule and acrylamide(AM) as the functional monomer. The ethylene glycol dimethacrylate,trimethylolpropane trimethacrylate, divinyl benzene, and pentaerythritol trimethacrylate are as the cross-linking agents, respectively. The acetonitrile, chloroform, toluene, and tetrahydrofuran are used as the solvents, respectively. The configurations of the molecular imprinting self-assembly system for PHN and AM have been simulated to study their bonding sites, binding energy, amount of hydrogen bond, and interaction mechanism. The essence of imprinting interaction for PHN and AM has been revealed by the atomic in the molecule theory. Meanwhile, the analogues of PHN were used to discuss the selectivity property of the stable PHN-AM complex. The results show that the PHN interacts with AM through hydrogen bonds. When the imprinting molar ratio of PHN-AM is1:6 and the THF is as the solvent, the amount of their hydrogen bonds is the most, the binding energy is the lowest, and their configuration is the most stable. In comparison with the other cross-linking agents(EGDMA, TRIM, and DVB), the PETA is more suitable for PHN-MIPs. The selective property of PHN-MIP to PHN is excellent when PHN and DMBA exist at the same time.

Direct Synthesis of Monodisperse Hollow Molecularly Imprinted Polymers Based on Unfunctionalized SiO2 for the Recognition of Bisphenol A

A novel and effective approach was developed to synthesize monodisperse hollow molecularly imprinted polymers （MHMIPs） with unfunctionalized SiO2 spheres in a mixture of toluene and CH3CN. The factors that affected the synthesis of MHMIPs were systematically investigated. It was determined that a suitable ratio of toluene to CH3CN and the use of a functional monomer that can generate double H-bonding interactions were the critical factors to obtain MHMIPs with high uniformity and rnonodispersion. The obtained MHMIPs exhibited a fast adsorption rate and high adsorption capacity （270 μmol/g） for bisphenol A. As the shell thickness increased from 90 nm to 130 nm, the binding capacity of the imprinted shells decreased gradually. The relative selectivity coefficients of MHMIPs for tetra-brornobisphenol A （TBBPA）, phenol and p-tert-butylphenol （PTBP） were calculated as 1.53, 1.83 and 1.90, respectively. These findings indicate that MHMIPs have good adsorption performances and suggest applications in the selective removal or sensitive analysis of bisphenol A.

The Development of Molecularly Imprinted Polymers in the Clean-Up of Water Pollutants: A Review

In the last decades, the extensive use of chemical and biological materials has not only seen to an increased transport of environmental pollutants but also, it has interfered and compromised the pristine state of different environmental matrices with emphasis on waterbodies. This has stimulated studies to develop and adopt novel techniques which consider the removal of pollutants with premium on economic feasibility, simple instrumentation, and high performance. In the treatment of water, the removal of trace concentration organic compounds and other numerous polluted water effluents is difficult due to limited affinity of trace compound ions to ion exchange resins. Because of the selective nature;recognition properties;adsorption ability;high stability;and easier preparation of molecular imprints, they are considered attractive and suitable artificial receptors to be applied in analytical separations, drug delivery, and as chemical sensors. In this review, we touch on the fundamentals of molecularly imprinted technologies and underscore some recent advances made in the development of imprinted polymers that are compatible with water and how they can be used in the clean-up of pollutants. The paper finally presents a comprehensive report on some challenges and outlook in the use of MIPs as water treatment sorbent.

Application of Molecularly Imprinted Polymers for the Analysis of Pesticide Residues in Food—A Highly Selective and Innovative Approach

The increasing application of pesticides for agricultural purposes involves serious risk to the environment and human health due to either exposure or through residues in food and drinking water. Since food safety is of mandatory importance there is a growing interest on the development of selective, simple, rapid, cost-effective and reliable analytical methodologies in order to ensure that pesticides residues should not be found at levels above the established maximum pesticide residue limits (MRLs). In recent years, a new methodology based on the development of molecularly imprinting polymers (MIPs) allows not only pre-concentration and cleaning of the sample but also selective extraction of the target analyte, which is crucial, particularly when the sample is complex and impurities can interfere with quantification. The scope of this review is to provide a general overview on MIPs field, with emphasis on MIP preparation and its use as sorbents for solid-phase extraction. This paper will be focused on the review of the current state of the art in the use of MIPs as selective materials in molecularly imprinted solid-phase extraction (MISPE) for the analysis of pesticide residues from food matrices. A review of preparation and application of MIPs in food matrices, will also be discussed.

The Application of Molecularly Imprinted Polymers

Molecularly imprinted technology (MIT) has the characteristics of specificity and high selectivity, which is one of the most promising methodologies. Besides, the polymers are made using MIT as the functional material of solid-phase extraction and chromatographic fractionating and sensor, because of the characteristics of the high selectivity, the better stability and easy preparation. This review introduces the progress in the application of MIT and summarizes its application in the chemistry.

Recent advances in magnetic molecularly imprinted polymers and their application in the food safety analysis

Food safety is a worldwide concern and is directly related to human health.Therefore,convenient,effective,and economical methods and technologies for food safety analysis have been developed continuously.Magnetic molecularly imprinted polymers(MMIPs)have gained extensive attention in recent years,as they have high selectivity,high adsorption capacity,and are easy to isolate from food samples.Recently,advanced strategies for the synthesis of MMIPs have been proposed to solve problems of template leakage and non-specific adsorption,and to increase the biocompatibility,adsorption rate,as well as adsorption capacity of the imprinted materials.In this review,we focus on new attempts at modification of magnetic core and MMIPs’surfaces,and the selection of template,functional monomer,cross-linker as well as porogen.Studies are summarized that used advanced MMIPs for the recognition and adsorption of pesticide residues,veterinary drug residues,mycotoxins,contaminants,and adulterations in foodstuffs over the last 5 years.Finally,some still existing challenges and future prospects to further promote MMIPs properties are also discussed.

Preparation of hydrophilic molecularly imprinted polymers for tetracycline antibiotics recognition

Hydrophilic molecularly imprinted polymers（MIPs） were prepared using tetracycline as template,methacrylic acid as monomer and glycidilmethacrylate as pro-hydrophilic co-monomer.Compared with common MIPs,the imprinting effect and adsorption amounts of hydrophilic MIPs for tetracycline（TC） were greatly improved in water media.Furthermore,the electrochemical sensor fabricated by modifying hydrophilic MIPs on glassy carbon electrode was developed for the determination of TC in foodstuff samples.

Molecularly Imprinted Polymers Based Surface Plasmon Resonance Sensor for Sulfamethoxazole Detection

Sulfamethoxazole(SMX)is a sulfonamide antibiotic primarily used to treat urinary tract infections and used in veterinary and industrialized husbandry to treat diseases and food additives.Like other antibiotics,SMX is considered as a pollutant in water and food that threaten local life.This study developed a surface plasmon resonance(SPR)sensor chip that is fast,highly selective,and reusable,and requires no pretreatment for detecting SMX.As a receptor,SMX imprinted methacrylic acid-2-hydroxyethyl methacrylate-ethylene glycol dimethacrylate polymer[poly(MAA-HEMA-EGDMA)]was used.The surface of the gold SPR chips was coated with a drop-casting method.The nanofilm coated chips were characterized by scanning electron microscopy(SEM),atomic force microscopy(AFM),ellipsometer,contact angle measurement,and Fourier-transform infrared spectrometry(FTIR).Imprinting factor(IF)was calculated as:ΔR[MIP(molecularly imprinted polymers)]/ΔR[NIP(non-imprinted)]=12/3.5=3.4.Limit of detection(LOD)and limit of quantification(LOQ)values were calculated with 3 s/m and 10 s/m methods,and the results were found to be 0.0011μg/L for LOD 0.0034μg/L for LOQ.Adsorption studies on both standard SMX solution and commercial milk samples were applied.Also,we investigated the developed chip’s reusability,storability,and selectivity with amoxicillin and cefalexin.

Preparation and Evaluation of Molecularly Imprinted Monolithic Column for Felodipine in Micro-liquid Chromatography

This study concentrated on the production of molecularly imprinted polymers (MIPs) as highly selective sorbents for felodipine (FLD), a representive dihydropyridine calcium antagonists. Demonstrated chromatographically through a selection factor, these MIPs showed high selectivity for the template molecule among a group of structurally similar compounds. The recognition was found to correlate with structural similarity to the template compound.