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 bowl-shaped polydopamine surface imprinted polymer composite adsorbent for specific separation of 2'-deoxyadenosine

Molecularly imprinted polymers (MIPs) have great potential as adsorbents for selective adsorption and separation of nucleoside compounds,but effectively enhancing the affinity of recognition sites by adjusting the forces between template molecules and functional monomers remains an important challenge.In this work,a surface imprinting strategy was used to construct bowl-shaped molecularly imprinted composite sorbents (BHPN@MIPs) based on polydopamine (PDA) particles and have achieved selective separation and purification of 2'-deoxyadenosine (dA).Where by the base complementary pairing interaction of the combined template molecule d A and the pyrimidine functional monomer can enhance the preassembly force,and the hydrophilic bowl-shaped PDA can provide a larger storage space contact efficiency of d A in the test solution,causing the site utilization much higher and improving the kinetic adsorption performance.The equilibrium adsorption time and maximum adsorption capacity of60 min and 328.45μmol·g^(-1)were observed by static adsorption experiments,and the selectivity experimental results showed an imprinting factor IF of 1.30.After four adsorption–desorption cycles,the initial adsorption equilibrium adsorption capacity of BHPN@MIPs still retained 91.14%.By evaluating the selective adsorption of d A in spiked human serum solutions,BHPN@MIPs can be used to selectively enrich and analyze target d A in complex biological samples.

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%.

Synthesis and Adsorption Study of BSA Surface Imprinted Polymer on CdS Quantum Dots

A new bovine serum albumin （BSA） surface imprinting method was developed by the incorporation of quantum dots （QDs） into molecularly imprinted polymers （MIP）, which can offer shape selectivity. Preparation and adsorption conditions were optimized. Physical appearance of the QDs and QDs-MIP particles was illustrated by scanning electron microscope images. Photoluminescence emission of CdS was quenched when rebinding of the template.The quenching of photoluminescence emissions is presumably due to the fluorescence resonance energy transfer between quantum dots and BSA template molecules. The adsorption is compiled with Langmuir isotherm, and chemical adsorption is the rate-controlling step.The maximum adsorption capacity could reach 226.0 mg/g, which is 142.4 mg/g larger than that of undoped BSA MIP. This study demonstrates the validity of QDs coupled with MIP technology for analyzing BSA.

Ion imprinted polymer particles of neodymium:synthesis,characterization and selective recognition

Neodymium ion imprinted polymer（Nd^3＋-IIP） particles for selective solid-phase extraction of Nd^3＋ were prepared and determined with inductively coupled plasma atomic emission spectrometry（ICP-AES）.The unleached Nd^3＋-IIP particles were prepared by the copoly-merization of Nd^3＋-5,7-dichloroquinoline-8-ol-4-vinylpyridine ternary complex with styrene and divinyl benzene, then Nd^3＋ was leached to obtain Nd^3＋-IIP particles.The adsorption capacity of the Nd3＋-IIP was 35.18 mg/g.The largest selectivity coefficient for Nd3＋ in the presence of competitive ions such as La^3＋, Ce^3＋, Pr^3＋ and Sm^3＋ was over 110.The proposed method was validated by analyzing two certified reference materials（GBW07301a sediment and GBW07401 soil） and the determined values were in a good agreement with standard values.The method was convenient, selective, sensitive and applicable to the determination of trace Nd^3＋ in environmental samples with complicated matrix.

A novel surface molecularly imprinted polymer as the solid-phase extraction adsorbent for the selective determination of ampicillin sodium in milk and blood samples

Surface molecularly imprinted polymers （SMIPs） for selective adsorption of ampicillin sodium were synthesized using surface molecular imprinting technique with silica gel as a support. The physical and morphological characteristics of the polymers were investigated by scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FT-IR）, thermogravimetric analysis （TGA）, elemental analysis and nitrogen adsorption-desorption test. The obtained results showed that the SMIPs displayed great adsorption capacity （13.5 lag/mg）, high recognition ability （the imprinted factor is 3.2） and good binding kinetics for ampicillin sodium. Finally, as solid phase extraction adsorbents, the SMIPs coupled with HPLC method were validated and applied for the enrichment, purification and determination of anapicillin sodium in real milk and blood samples. The averages of spiked accuracy ranged from 92.1% to 107.6%. The relative standard deviations of intra- and inter-day precisions were less than 4.6%. This study provides a new and promising method for enriching, extracting and determining ampicillin sodium in complex biological samples.

Recognition Interactions of Metal-complexing Imprinted Polymer

Molecularly imprinted polymer, exhibiting considerable enantioselectivity for L-mandelic acid, was prepared using metal coordination-chelation interaction. By evaluating the recognition characteristics in the chromatographic mode, the recognition interactions were proposed: specific and nonspecific metal coordination-chelation interaction and hydrophobic interaction were responsible for substrate binding on metal-complexing imprinted polymer; while the selective recognition only came from specific metal coordination-chelation interaction and specific hydrophobic interaction.

Molecularly imprinted polymer based on upconversion nanoparticles for highly selective and sensitive determination of Ochratoxin A

A novel molecularly imprinted polymer (MIP) based on upconversion nanoparticles (UCNPs) was successfully synthesized for determination of Ochratoxin A (OTA). The MIP was developed on the silica-coated UCNPs using N-(1-hydroxy-2-naphthoyl amido)-(L)-phenylalanine (HNA-Phe) as the alternative template. The final composite combined the advantages of the high selectivity of MIP with the high fluorescence intensity of UCNPs which was selective and sensitive to OTA. Under the optimal condition, the fluorescence intensity of UCNPs@SiO2@MIP decreases linearly when the concentration of OTA increases from 0.05 to 1.0 mg/L. The detection limit of OTA with the method was 0.031 mg/L. At three spiked concentration levels (50, 100 and 200 μg/kg), the recovery ranges of OTA in corn, rice and feed are 88.0%–91.6%, 80.2%–91.6% and 89.2%–90.4%, respectively.

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.

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%.

Sensitivity Enhancement in Uranium Determination by UV-Visible Spectroscopy Using Ion Imprinted Polymer

There is need to determination of uranium concentration at ppb level in environmental matrices.Due to low sensitivity of FAAS,UV-Visible Spectroscopy is generally used as measurement technique.In this study,ion-imprinted polymers(IIP)were prepared for uranyl ion(imprint ion)by formation of ternary(salicylaldoxime and 4-vinylpyridine)complex in 2-methoxy ethanol(porogen)following copolymerization with methacrylic acid(MAA)as a functional monomer and ethylene glycol dimethacrylate(EGDMA)as crosslinking monomer using 2,2-azobisisobutyronitrile as initiator.The synthesized polymers were characterized by FTIR and TGA analysis.ArsenazoⅢin 3M HClO_4 was used as complexing agent in the measurement step.The optimal pH for preconcentration was found to be between 3.5~6.5values.The developed method was applied to uranium(Ⅵ)determination in natural water samples.

Preparation and Aqueous Recognition of Metal Complex Imprinted Polymer Using N-vinyl-2-pyrrolidone as Functional Monomer

Using nickel（II） acetate.-2,2＇-dipyridyl complex as template and N-vinyl-2-pyrrolidone （NVP） as coordinate functional monomer,.a new kind of metal-compiexing template molecularly impnnted polymer （MIP） was prepared..The results of equilibri.um binding experiments in. aqueous solution showed that the MIP had higher＇binding capacity for nickel（ II ）-2,2＇-dipyridyl than the non-imprinted polymer with the same chemical composition. Theinfluences of metal ions and pHof solution on the recognition performance of MIP were investigated. The bindingcharacteristics of MIP were evaluated by the Scatchard analysis with one-site and two-site binding equations, respectively. The results on substrate selectivity of imprinted polymer revealed that MIP had better binding affinityfor template among thetested compounds.

Synthesis of Molecularly Imprinted Polymer Particles by Suspension Polymerization in Silicon Oil

Molecularly imprinted polymers using 2,4-dichlorophenoxyacetic acid （2,4-D） as templates were prepared by suspension polymerization in silicon oil. The polymer particles exhibited regular shape in the micro-scale range. The adsorbing experiments indicated that the imprinted polymer particles possessed higher affinity to 2,4-D than the non-imprinted polymer particles.

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.

Development and Characterization of an Electrochemical Sensor for Cinchonidine Detection Based on Molecularly Imprinted Polymer with Modified Rosin as Cross-linker

Molecularly imprinted polymers（MIPs） were applied as molecular recognition elements to an electro- chemical sensor for cinchonidine（CD）. A kind of MIP was synthesized with cinchonidine as template, modified ro- sin（ethylene glycol maleic rosinate acrylate） containing the skeleton of phenanthrene rings as cross-linker and me- thylacrylic acid as functional monomer. MIP membrane was prepared on a glassy carbon electrode for the determina- tion of CD via free radical polymerization method. Electrochemical impedance spectroscopy（EIS） and cyclic vol- tammetry（CV） were used to characterize the membrane electrochemical behavior in electrode fabrication process. The experimental conditions were discussed. Under optimum conditions, it was found that the response of peak cur- rents was linear to the concentration of CD in a range of 0.013-2.26 mmol/L. The detection limit for CD is 1 μmol/L the relative standard deviation for 100 μmol/L CD is 1.34% and the incubation time is 2 min. The sensor was applied to the determination of CD in urine samples with satisfactory results.

Synthesis, adsorption and selectivity of inverse emulsion Cd(Ⅱ) imprinted polymers

Inverse emulsion polymerization was employed to synthesize inverse emulsion Cd（Ⅱ） imprinted polymers （IEⅡ P）. The morphology and functional groups of IEⅡP were characterized by SEM,FTIR and TG. Static adsorption experiments and competitive adsorption test were used to evaluate the adsorption ability of IEⅡP. The adsorption capacity of polymers could reach 86.7 mg·g^-1 under the optimal adsorption conditions. The pseudo second order kinetic model and Langmuir isotherm model could be used to analyze the experimental data well. The adsorption process of IEⅡP was chemical adsorption process and monomolecular type. Thermodynamic parameters showed that the adsorption process was endothermic and could occur spontaneously. The selectivity coefficients k of Cd^2＋/v, Cd^2＋/Zn^2＋ and Cd^2＋/Cu^2＋ were 2.4998, 1.2437 and 4.6882, respectively. The proposed method provides a new thought for removing Cd（Ⅱ） in water samples.

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.

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.

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.