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.

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%.

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.

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%.

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.

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.

Determination of cytokine regulated glycan expression by using molecularly imprinted polymers targeting sialic acid

Cancer cells often have an increased amount of glycans, such as sialic acid (SA), on the cell surface, which normally play an important role in cell growth, proliferation and differentiation. In this study, SA expression is determined by fluorescent nanoprobes, molecularly imprinted polymers, SA-MIPs. The nanoprobes are synthesized with an imprinting approach to produce tailor-made fluorescent core-shell particles with high affinity for cell surface SA. Inflammation and cytokine production are well known tumor promoters, modulating the cellular microenvironment, including an aberrant cell surface glycan pattern. The recombinant cytokines IL-4, IL-6, IL-8 and a cocktail of cytokines collected from stimulated T leukemia Jurkat cells were used to induce in vitro inflammation in two cell lines, and thereafter analyzed with the use of SA-MIPs and flow cytometry. One of the cell lines showed a different binding pattern of SA-MIPs after treatment with recombinant cytokines and the cytokine cocktail. This study shows that SA-MIPs can be an important tool in the investigation of overexpressed glycans in the tumor microenvironment.

Selective Solid-phase Extraction of Aloe Emodin from Aloe by Molecularly Imprinted Polymers

The extraction and separation of aloe emodin were optimized via selective molecularly imprinted solid-phase extraction. Molecularly imprinted polymer was prepared from the functional monomer, methacrylic acid and a mixture of ethanol/dodecanol（90/10, volume ratio） as porogen. It overcomes the common problems of imprin- ting biological polar compounds and shows high selectivity compared favorably with those of non-imprinted polymer and commercially available C18 and silica cartridges in similar aloe emodin tests. Good linearity was obtained be- tween 0.002 and 2.5 mg/mL（r2=0.998） with relative standard deviations below 3.3%.

Theoretical Design and Adsorption Properties of Molecularly Imprinted Polymers Obtained from Chloramphenicol and Acrylamide

Molecular simulations are widely used to model molecularly imprinted polymers(MIPs)in order to enliance their adsorption and selectivity.In this study,chloramphenicol(CAP)and acrylamide(AM)were used as the template and flinctional monomer,respectively,and pentaenlhritol triacrylate(PETA),ethylene glycol dimethacrylate(EGDMA),and trimethvlolpropane trimethvlacrylate(TRIM)were used as cross-linking agents.The 6oB97XD/6-31 density functional theory method was employed to simulate binding sites,binding energy,the number of hydrogen bonds,the imprinted molar ratio,which produced the most stable complex,and the interaction mechanism.The cross-linking agent was optimized based on the binding energy.The atoms in molecules theory were used to study the nature of the imprinting effects.The theoretical calculations revealed that CAP and AM fonned ordered complexes via hydrogen bonding interactions when the molar ratio between CAP and AM was 1:7 using TRIM as the cross-linking agent.The CAP-AM complex(molar ratio 1:7)had the most stable structure,the largest number of hydrogen bonds,and the smallest AE.The experimental results indicate that the CAP-MIPs ionncd perfect microspheres with an average particle size of 314 nm.Scat chard plot analysis showed that the CAP-MIPs had only one type of binding site over thestudied concentration ranges.The dissociation equilibriinn constant and maximum apparent adsorption capacities were 1887.35 mg/L(5.84 mmol/L)and 155.56 mg/g(0.482 mmol/g),respectively.

Molecularly imprinted polymers as the extracted sorbents of clenbuterol ahead of liquid chromatographic determination

A pre-treatment methodology for clenbuterol hydrochloride （CLEN） isolation and enrichment in a complex matrix environment was developed through exploiting molecularly imprinted polymers （MIPs）. CLEN-imprinted pol- ymers were synthesized by the combined use of ally-β-cyclodextrin （ally-13-CD） and methacrylic acid （MAA）, allyl-β-CD and acrylonitrile （AN）, and allyl-β-CD and methyl methacrylate （MMA） as the binary functional monomers. MAA-linked allyl-β-CD MIPs （M-MAA） were characterized by Fourier transform-infrared （FT-IR） spectroscopy and a scanning electron microscope （SEM）. Based upon the results, M-MAA polymers generally proved to be an excellent selective extraction compared to its references： AN-linked allyl-β-CD MIPs （M-AN） and MMA-linked allyl-β-CD MIPs （M-MMA）. M-MAA polymers were eventually chosen to run through a molecularly imprinted solid-phase extraction （MISPE） micro-column to enrich CLEN residues spiked in pig livers. A high recovery was achieved, ranging from 91.03% to 96.76% with relative standard deviation （RSD） ≤4.45%.

Surface plasmon resonance sensor chips for the recognition of bovine serum albumin via electropolymerized molecularly imprinted polymers

In this paper, a surface plasmon resonance （SPR） sensor chip for detection of bovine serum album （BSA） was prepared by electropolymerization of 3-aminophenylboronic acid （3-APBA） based on molecularly imprinted polymer （MIP） technique. The surface morphology of MIP and non-imprinted （NIP） films were characterized by scanning electroscopy （SEM）. SEM images exhibited nanoscale cavities formed on the MIP films surface homogeneously due to the removal of BSA templates. The effects of pH, ion strength of rebinding BSA, the specific binding and selective recognition were studied for MIP films. Results indicated that the BSA-imprinted films exhibited a good adsorption of template protein （0.02-0.8 mg/mL） in 0.05 mol/L sodium phosphate buffer at pH 5.0 with the limit of detection （LOD） of 0.02 mg/mL.

Detection of TNT by Surface Plasmon Resonance Based on Molecularly Imprinted Polymers

2,4,6-trinitrotoluene(TNT)is a commonly used explosive.It is not only a threat to public safety but also causes environmental pollution,affecting human health.However,at this stage of TNT detection,technology cannot meet the demands of the current situation.To acquire a new method devoted to the study of fast and quantitative detection of TNT.It combines the molecular imprinting technique(MIT)with surface plasmon resonance(SPR)technology for high sensitivity.In this study,a molecularly imprinted polymer(MIP)film for the detection of TNT was synthesized by heat in acetonitrile at 60°C,using the TNT imprinting molecule and azobisisobutyronitrile(AEBN)as initiators.In the present work,there are many factors that can influence the elution efficiency,such as raw material ratios,fore-reaction time,reaction time,etc.The polymers have the highest elution efficiency when raw material mole ratios[n(TNT):n methacrylic acid(MAA):n ethylene glycol dimethylacrylate(EGDMA)]were 1:4:8;the MIP sensor could detect a TNT concentration as low as 1x10-10 M.Compared to the blank polymer with the same chemical composition,the imprinted polymer had higher binding efficiency and higher selectivity.