Performance Of Molecularly Imprinted Polymers Research Articles

Preparation of a surface molecularly imprinted thermo-sensitive polymer for selective trypsin capture

Molecularly imprinted polymers (MIPs) are innovative porous materials created through polymerization templating methods for highly selective, sensitive detection and separation of the desired chemical species, known as template molecules. Surface imprinting over nano-sized substrates with special functional groups is an effective approach for improving the mass transfer and rebinding capacity. In this study, we successfully performed surface imprinting using methacrylic acid (MAA) and thermoresponsive N-isopropyl acrylamide (NIPAm) as functional monomers on acrylic-functionalized silica nanoparticles and served as a Trypsin artificial receptor. The resulting Trypsin imprinted polymer exhibited a binding capacity of 1022.44 mg/g, surpassing the non-imprinted polymer’s capacity of 292.41 mg/g within 45 min. Moreover, the imprinting factor, the main influence factor in MIP performance, was 3.5, demonstrating the significant selectivity of the polymeric products. In addition, due to the temperature sensitivity of NIPAm the template removing process was simply done by changing pore size. The silica nanoparticles and the synthesized MIP particles had diameters of approximately 95 nm and 105 nm, respectively, with the polymer layer thickness being around 5 nm. The MIP adsorption model followed the Freundlich isotherm and pseudo-second-order kinetics resulting in efficiencies of 93.0 % and 95.4 %, respectively. The developed Trypsin imprinted polymer was reusable for four consecutive uses,demonstrating both resilience and selectivity towards Trypsin.

Unraveling multi-template molecularly imprinted polymer for selective extraction of triazole antifungals: Theoretical and experimental investigation

Fungal coinfection is an emerging problem in the COVID-19 pandemic. Aspergillus and Candida species are the most prevalent pathogens. Therapeutic drug monitoring of triazole antifungals as a first-line therapy is required to increase their effectiveness and minimize toxicity. Bioanalysis of triazole antifungals requires selective extraction because of the complexity of matrices. Molecularly imprinted polymers (MIP) are potential solutions for increasing selectivity. This study aimed to synthesize a selective MIP sorbent to simultaneously determine voriconazole, itraconazole, and fluconazole concentrations through computational and laboratory studies. The host-guest interaction was used in the selection of monomer and solvent. The synthesis was optimized by precipitation and bulk methods using single and multi-template. Adsorption tests, characterizations, and application to the sample were performed to analyze the MIP performance. The optimal synthesis obtained using the precipitation method with mol ratio of template:monomer:crosslinker was 1:4:20. Adsorption equilibrium was established within 3 h and following pseudo-second-order kinetic. The MIP-P9 provided the highest adsorption capacity and followed the Freundlich isotherm. Characterization of MIP confirmed the successful synthesis and template removal of MIP. MIP was selective to triazole antifungals and had higher recovery than NIP and SPE C18. Based on these findings, MIP can be utilized for direct separation in clinical analysis.

Innovative approaches to suppress non-specific adsorption in molecularly imprinted polymers for sensing applications

Molecularly imprinted polymers (MIPs) are synthetic antibodies developed to bind selectively with specific molecules. They function through a particular recognition process involving their cavities and functional groups. Nevertheless, functional groups located outside these cavities are the main cause of non-specific molecule binding, thus reducing the effectiveness of MIPs in sensing applications. This work focused on enhancing the selectivity and performance of MIPs through electrostatic modification with surfactants. The study investigates the use of two surfactants, namely sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB), to eliminate non-specific adsorption in MIPs. The binding isotherms of the target molecule sulfamethoxazole (SMX) on MIPs and non-imprinted polymers (NIPs) were analyzed, showing higher adsorption capacity of MIPs due to the specific cavities. The modification with SDS or CTAB effectively eliminated non-specific adsorption in MIPs. The kinetic adsorption behavior further demonstrated the efficacy of MIP+--SDS/CTAB in the selective adsorption of SMX. Calibration curves showcase the methodology's analytical capabilities, achieving low limit of detection for SMX 6 ng mL−1 using MIP +-SDS. The stability study confirmed that the developed MIP +/--SDS/CTAB remains stable even at high temperatures, demonstrating its suitability for on-site applications. The methodology was successfully applied to detect SMX in milk and water samples, achieving promising recoveries. Overall, the electrostatic modification of MIPs with surfactants emerges as a valuable strategy for enhancing selectivity and performance in target molecule recognition and detection.

Application of molecularly imprinted polymers (MIPs) as environmental separation tools

This review is structured to outline the applications of MIPs as environmental separation tools and assess the role of functional groups as a parameter influencing MIP performance.

Molecularly imprinted dispersive micro solid-phase extraction and tandem derivatization for the determination of histamine in fermented wines.

Histamine causes allergic reactions and can serve as an indicator for assessing food quality. This study designed and developed a dispersive micro solid-phase extraction (D-μSPE) method that combined the advantages of dispersive liquid-liquid extraction and solid-phase extraction (SPE). Molecularly imprinted polymers (MIPs) were employed as the solid phase in the D-μSPE method to extract histamine in wine samples. We used microwave energy to significantly reduce the synthesis time, achieving an 11.1-fold shorter synthesis time compared to the conventional MIP synthetic method. Under optimized D-μSPE conditions, our results showed that the dispersive solvent could effectively increase the adsorption performance of MIPs in wine samples by 97.7%. To improve the sensitivity of histamine detection in gas chromatography-mass spectrometry, we employed the microwave-assisted tandem derivatization method to reuse excess derivatization reagents and reduce energy consumption and reaction time. Calibration curves were constructed for wine samples spiked with 0-400 nmol histamine using the standard addition method, resulting in good linearity with a coefficient of determination of 0.999. The intra- and inter-batch relative standard deviations of the slope and intercept were < 0.7% and < 5.3%, respectively. The limits of quantitation and detection were 0.4 nmol and 0.1 nmol, respectively. The developed method was successfully applied to analyze the histamine concentration in 10 commercial wine samples. In addition, the AGREEprep tool was used to evaluate the greenness performance of the developed method, which obtained a higher score than the other reported methods.

Bibliometric research analysis of molecularly imprinted polymers (MIPs): evidence and research activity dynamics

The escalating issue of water pollution has become a worldwide issue that has captured the attention of numerous scientists. Molecularly imprinted polymers (MIPs) have emerged as adaptable materials with exceptional attributes, including easy synthesis, low cost, remarkable durability, long life, and accessibility. These attributes have motivated researchers to develop novel materials based on MIPs to tackle hazardous contaminants in environmental matrices. The purpose of this paper was to conduct a bibliometric analysis on MIPs’ publications, in order to shed light on the developments and focus points of the field. The selected publications were obtained from Scopus database and subjected to a filtering process, resulting in 11,131 relevant publications. The analysis revealed that the leading publication source (journal) is Biosensors and Bioelectronics; the mostly employed keywords are solid-phase extraction, electrochemical sensor, and molecular recognition; and the top contributing countries are China, Iran, and the USA. The Latent Dirichlet Allocation (LDA) algorithm was used for extracting thematic axes from the textual content of the publications. The results of the LDA model showcase that the topic of synthesis and performance of MIPs for environmental applications can be considered as the most dominant topic with a share value of 72.71%. From the analysis, it can be concluded that MIPs are a cross-disciplinary research field.

Synthesis of molecularly imprinted polymer for the removal of cyanazine from aqueous samples

BackgroundCyanazine (CYZ) is one of the triazine herbicides to prevent broadleaf grass and weeds in crops. Despite its affordability and productivity in increasing crop yield, the extensive usage of CYZ contributes to environmental pollution and poses risks to living organisms. Most research has focused on detecting CYZ in the environment and its toxicity to humans and the ecosystem. For these reasons, molecular imprinting technology (MIT) can be applied to produce an effective adsorbent material of high binding affinity and selectivity towards its target compound which is known as molecularly imprinted polymers (MIPs). In this study, MIP was prepared by precipitation polymerization using CYZ as a template molecule, methacrylic acid (MAA), acrylamide (AAm) and 4-vinylpyridine (4VP) as functional monomers, and ethylene glycol dimethacrylate (EGDMA) as cross-linker in the ratio of 1:6:12, respectively. The effects of contact time, initial concentration, pH, and polymer dosages on the adsorption efficiencies of MIPs were also investigated in this study.ResultsMIPs of CYZ were successfully synthesized by precipitation polymerization method with a non-covalent approach using different functional monomers such as methacrylic acid (MAA), acrylamide (AAm) and 4-vinylpyridine (4VP). For the comparison study, the non-imprinted polymer (NIP) was synthesized without the addition of CYZ, the template molecule. The FTIR analysis indicated the interactions among CYZ and functional monomers (MAA, AAm or 4VP) in the presence of EGDMA as a cross-linker. The FESEM analysis showed that only MIP (AAm) and NIP (AAm) had regular and spherical polymer particles while MIP (MAA), NIP (MAA), MIP (4VP) and NIP (4VP) were agglomerated and irregular in shape. The EDX analysis showed that the MIPs were mainly composed of carbon and oxygen. Meanwhile, the BET analysis of MIP (AAm) had higher surface area, total pore volume and average pore radius than that NIP (AAm). Based on the batch binding study, MIP (AAm) (83.30%) had the highest binding efficiency than the MIP (MAA) (76.96%) and MIP (2VP) (76.90%) at a contact time of 240 min. The optimum conditions for the highest binding efficiency of MIP (AAm) were obtained at an initial concentration of 6 ppm, pH 7 and polymer dosage of 0.1 g polymer beads. The adsorption efficiency of MIP (AAm) with CYZ at the optimum parameters resulted in 86.39%. The selectivity test showed that MIP (AAm) was more selective towards CYZ than AME, the competitive compound with relative selectivity coefficient of 2.36. The kinetic isotherm of MIP (AAm) was best explained according to the pseudo-second-order kinetic model while the adsorption isotherm of MIP (AAm) was based on the Langmuir adsorption isotherm model. The MIP (AAm) was tested in the distilled water (DIW), tap water and river water spiked with CYZ and a substantial amount of CYZ was removed with a recovery of 86.67%, 84.75% and 84.69%, respectively.ConclusionThe MIPs of CYZ were successfully synthesized by the precipitation polymerization method using different functional monomers. Among those MIPs, MIP (AAm) showed the highest rebinding efficiency and therefore this MIP was selected for further studies. The best combination of CYZ, AAm was the main factor that contributed to the morphological and chemical properties, as well as the efficiency and selective binding performance of MIP (AAm). Since MIP (AAm) showed a substantial removal efficiency of CYZ in the environment specifically water sources, it has the capability to act as an adsorbent material for various purposes such as solid-phase extraction techniques and a stationary phase in various chromatographic techniques.Graphical

Reshaping the imprinting strategy through the thermo-responsive moiety-derived “deep eutectic solvents” effect

As a new concept having emerged in last few years, the “deep eutectic solvents” (DESs) effect integrated into the imprinting technology inevitably exposes design limitations of stimuli-responsive molecularly imprinted polymers (MIPs), as well as inadequate analysis of the adsorption performance of MIPs. Herein, a simple yet defined N-isopropylacrylamide/(3-acrylamidopropyl) trimethylammonium chloride (NIPAM/APTMAC) binary DESs system was proposed to prepare intelligent MIPs with thermo-sensitivity. Accordingly, magnetic and thermo-responsive MIPs based on functional monomers-derived DESs (TM-DESs-MIPs1) were synthesized, revealing DESs effect-regulated affinity/kinetics for the enhanced adsorption capability, eco-friendly thermo-regulated elution for high release efficiency, and simple magnetic separation, along with superior selectivity to rhein (RH) and good regeneration ability. TM-DESs-MIPs1 were utilized to extract RH from Cassiae semen samples coupled with high performance liquid chromatography (HPLC), yielding satisfactory recoveries (79.47%−110.82%) and low limits of detection (LOD) (16.67 µg/L). Another two kinds of MIPs adopting the thermo-responsive moiety-derived DESs effect strategy further demonstrated great applicability of such intelligent MIPs for analyses of complicated samples.

Application of Molecularly Imprinted Electrochemical Biomimetic Sensors for Detecting Small Molecule Food Contaminants.

Environmental chemical contaminants in food seriously impact human health and food safety. Successful detection methods can effectively monitor the potential risk of emerging chemical contaminants. Among them, molecularly imprinted polymers (MIPs) based on electrochemical biomimetic sensors overcome many drawbacks of conventional detection methods and offer opportunities to detect contaminants with simple equipment in an efficient, sensitive, and low-cost manner. We searched eligible papers through the Web of Science (2000-2022) and PubMed databases. Then, we introduced the sensing mechanism of MIPs, outlined the sample preparation methods, and summarized the MIP characterization and performance. The classification of electrochemistry, as well as its advantages and disadvantages, are also discussed. Furthermore, the representative application of MIP-based electrochemical biomimetic sensors for detecting small molecular chemical contaminants, such as antibiotics, pesticides, toxins, food additives, illegal additions, organic pollutants, and heavy metal ions in food, is demonstrated. Finally, the conclusions and future perspectives are summarized and discussed.

Molecularly Imprinted Polymer-Based Sensor for Electrochemical Detection of Cortisol.

As a steroid hormone, cortisol has a close relationship with the stress response, and therefore, can be used as a biomarker for early detection of stress. An electrochemical immunosensor is one of the most widely used methods to detect cortisol, with antibodies as its bioreceptor. Apart from conventional laboratory-based methods, the trend for cortisol detection has seemed to be exploiting antibodies and aptamers. Both can provide satisfactory performance with high selectivity and sensitivity, but they still face issues with their short shelf life. Molecularly imprinted polymers (MIPs) have been widely used to detect macro- and micro-molecules by forming artificial antibodies as bioreceptors. MIPs are an alternative to natural antibodies, which despite demonstrating high selectivity and a low degree of cross-reactivity, often also show a high sensitivity to the environment, leading to their denaturation. MIPs can be prepared with convenient and relatively affordable fabrication processes. They also have high durability in ambient conditions, a long shelf life, and the ability to detect cortisol molecules at a concentration as low as 2 ag/mL. By collecting data from the past five years, this review summarizes the antibody and aptamer-based amperometric sensors as well as the latest developments exploiting MIPs rather than antibodies. Lastly, factors that can improve MIPs performance and are expected to be developed in the future are also explained.

Construction of PEGylated boronate-affinity-oriented imprinting magnetic nanoparticles for ultrasensitive detection of ellagic acid from beverages.

Molecularly imprinted polymers (MIPs) can exhibit antibody-level affinity for target molecules. However, the nonspecific adsorption of non-imprinted regions for non-target molecules limits the application range of MIPs. Herein, we fabricated PEGylated boronate-affinity-oriented ellagic acid-imprinting magnetic nanoparticles (PBEMN), which first integrated boronate-affinity-oriented surface imprinting and sequential PEGylation for small molecule-imprinted MIPs. The resultant PBEMN possess higher adsorption capacity and faster adsorption rate for template ellagic acid (EA) molecules than the non-PEGylated control. To prove the excellent performance, the PBEMN were linked with hydrophilic boronic acid-modified/fluorescein isothiocyanate-loaded graphene oxide (BFGO), because BFGO could selectively label cis-diol-containing substances by boronate-affinity and output ultrasensitive fluorescent signals. Based on a dual boronate-affinity synergy, the PBEMN first selectively captured EA molecules by boronate-affinity-oriented molecular imprinted recognition, and then the EA molecules were further labeled with BFGO through boronate-affinity. The PBEMN linked BFGO (PBPF) strategy provided ultrahigh sensitivity for EA molecules with a limit of detection of 39.1fgmL-1, resulting from the low nonspecific adsorption of PBEMN and the ultrasensitive fluorescence signal of BFGO. Lastly, the PBPF strategy was successfully employed in the determination of EA concentration in a spiked beverage sample with recovery and relative standard deviation in the range of 96.5 to 104.2% and 3.8 to 5.1%, respectively. This work demonstrates that the integration of boronate-affinity-oriented surface imprinting and sequential PEGylation may be a universal tool for improving the performance of MIPs.

Molecularly Imprinted and Cladded Nanoparticles Provide Better Phosphorylation Recognition.

Phosphorylation is one of the most frequently occurring post-translation modifications in mammals. Because abnormal protein phosphorylation is related to many diseases, phosphorylation analysis is essential for a sound understanding of protein phosphorylation and its relationship with diseases. Among several types of reagents for phosphorylation recognition, molecularly imprinted polymers (MIPs), as synthetic mimics of antibodies, have exhibited unique strengths that can overcome the drawbacks of biological reagents. However, the performance of current MIPs has remained unideal. Meanwhile, while the currently existing imprinting methods have permitted the production of several material formats, such as crushed particles and mesoporous nanoparticles, a general method allowing for the preparation of monodispersed molecularly imprinted nanoparticles has not been developed yet. Herein, we report a new approach called reverse microemulsion template docking surface imprinting and cladding (RMTD-SIC) for facile preparation of monodispersed imprinted nanoparticles for better phosphorylation recognition. Through rational design and controllable engineering, monodisperse imprinted and cladded nanoparticles specific to general phosphorylation and tyrosine phosphorylation were synthesized, which yield the highest imprinting factors as compared with published studies. The prepared nanomaterials exhibited excellent specificity and affinity, allowing for specific enrichment and improved mass spectrometric identification of target phosphorylated peptides from complex samples containing 100-fold more abundant interfering peptides. Therefore, the RMTD-SIC approach holds great potential for phosphorylation analysis and phosphorylation recognition-based applications.

Preparation of liquid crystal-based molecularly imprinted monolith and its molecular recognition thermodynamics

液晶分子印迹聚合物(MIPs)因刚性液晶单体的加入而在超低交联度水平下也能印迹和识别模板分子,有效解决了传统MIPs因高交联度造成的位点包埋、结合容量低、传质慢等问题。尽管液晶MIPs具有如此独特的优势,但却面临着由于交联度的大幅度降低而导致印迹效果下降的问题。为了研究液晶MIPs的结合特性,制备具有良好印迹效果的低交联液晶MIPs,该文通过二次接枝聚合,制备了一系列不同交联度的液晶分子印迹整体柱,用高效液相色谱法研究了聚合参数与印迹整体柱亲和性的关系。实验中选用三羟甲基丙烷三甲基丙烯酸酯(TRIM)为交联剂,以甲苯和十二醇为致孔剂合成整体柱骨架,并在此基础上以(S)-萘普生为模板,加入液晶单体4-氰基苯基单环己基乙烯(CPCE)进行二次聚合接枝。实验中系统考察了流动相中乙腈比例及缓冲液pH值对色谱保留的影响,结果发现液晶单体的加入使得MIPs对萘普生保留控制机制由原来的氢键作用变为了疏水作用;通过动态吸附实验得到的突破曲线经前沿分析及对吸附等温线Langmuir、Freundlich和Scatchard分析拟合,发现交联度为15%时液晶MIPs印迹因子最大(3.78)、非均一性最强,且特异性吸附量高于非特异性吸附量。液晶MIPs的计量置换模型(SDM-R)分析表明,液晶印迹整体柱对模板分子的总亲和力(ln A=0.645)明显高于其类似物;而从空间匹配程度看,与液晶印迹整体柱空间匹配程度最高的是酮洛芬而非模板分子,但液晶印迹整体柱对酮洛芬的总亲和力(ln A=0.242)不及模板分子的一半,表明在本低交联液晶印迹系统中,空间效应不是决定印迹系统识别能力的主要因素。进一步的分离热力学研究发现,低交联液晶印迹柱的|ΔΔH|<T|ΔΔS|,而交联度为70%的非液晶MIPs柱的|ΔΔH|>T|ΔΔS|,表明液晶MIPs的分离过程是一个熵控制过程,而常规无液晶MIPs的分离过程是一个焓控制过程。上述结果表明,液晶单体的加入改变了MIPs的识别机制,适当的低交联度可显著提高液晶MIPs的识别性能,因此液晶MIPs这些特质有望使其成为新一代的MIPs。

Selective recognition of a cyclic peptide hormone in human plasma by hydrazone bond-oriented surface imprinted nanoparticles

As a kind of artificial recognition material, molecularly imprinted polymers (MIPs) offer a promising perspective to be developed as synthetic chemical binders capable of selectively recognize biomacromolecules. However, owing to the large size and conformational flexibility of proteins and peptides, imprinting of these biomacromolecules remains a challenge. Novel imprinting strategies still need exploration for the improvement of recognition performance of MIPs. Herein, we developed a hydrazone bond-oriented surface imprinting strategy for an endogenous peptide hormone, human atrial natriuretic peptide (ANP). Surface-oriented imprinting of peptide via reversible covalent bond anchoring approach increased the orientation homogeneity of imprinted cavities as well as the utility of templates. The prepared nanoparticles exhibited high selectivity and fast recognition kinetics for ANP epitope. The dissociation constant between ANP epitope and MIP was measured as 5.3 μM. The applicability of the material in real samples was verified by the selective magnetic extraction of ANP from human plasma samples. This hydrazone bond-oriented surface imprinting strategy provides an alternative approach for the separation of peptides or proteins in complex bio-samples.

Effect of the Molecularly Imprinted Polymer Component Ratio on Analytical Performance.

Molecular imprinting technology is a new analytical method that is highly selective and specific for certain analytes in artificial receptor design. The renewal possibilities of this technology make it an ideal material for sundry application fields. Molecularly imprinted polymers (MIPs) are polymeric matrices that have molecules printed on their surfaces; these surfaces can chemically interact with molecules or follow the pattern of the available template cavities obtained using imprinting technology. A MIP is useful for separating and analysing complex samples, such as biological fluids and environmental samples, because it is a strong analytical recognition element that can mimick natural recognition entities like biological receptors and antibodies. The MIP components consist of the target template, functional monomer, crosslinker, polymerisation initiator, and porogen. The effectiveness and selectivity of a MIP are greatly influenced by variations in the components. This review will provide an overview of the effect of MIP component ratio on analytical performance to each target analyte; it will also provide a strategy to obtain the best MIP performance. For every MIP, each template : monomer : crosslinker ratio shows a distinct performance for a specific analyte. The effects of the template : monomer : crosslinker ratio on a MIP's analytical performances-measured by the imprinting factor, sorbent binding capacity, and sorbent selectivity-are briefly outlined.

Capacitive sensing of an amphetamine drug precursor in aqueous samples: Application of novel molecularly imprinted polymers for benzyl methyl ketone detection

Highly selective molecularly imprinted polymers (MIPs) towards benzyl methyl ketone (BMK) were synthesized for application as recognition elements in a capacitive sensor. A computational approach was employed to select the most appropriate monomers and cross-linkers. Using the selected compounds, different polymerization techniques and protocols were compared in order to study the effect on the MIP performance and characteristics. MIPs synthesized by bulk polymerization using itaconic acid and 1-vinylimidazole as monomers and p-divinylbenzene as cross-linker possess the highest affinity towards the target analyte. Prior to capacitive analysis, the developed particles were immobilized on the surface of gold transducers using tyramine as a linker. The validity of the developed sensor was checked by the BMK detection in spiked tap water and real water samples. A linear working range from 50 to 1000 μM was found while the limit of detection (LOD) was determined to be 1 μM in tap water. To the best of our knowledge, both the developed MIPs towards BMK and the electrochemical sensor for its detection have not been published or marketed to date.

A critical review of molecularly imprinted polymers for the analysis of organic pollutants in environmental water samples

Molecularly imprinted polymers (MIPs) with tailor-made recognition sites are used in water analysis for selective sample pretreatment before quantitation. The exceptional performance of MIPs with reduced interferences and matrix effects during sample preparation has resulted in selective and precise analytical methods by enhancing chromatographic separation and detection. MIPs are fabricated using a varying range of synthetic procedures and used as the adsorptive phase in solid phase extraction (SPE), dispersive solid phase extraction (DSPE), solid phase microextraction (SPME), stir bar sorptive extraction (SBSE), and membrane-based extraction techniques. In this paper, a comprehensive review of MIP technologies reported in the literature for water analysis is provided. MIPs are critically evaluated using key performance criteria, such as adsorption capacity, imprinting factor, chromatographic retention factor, and cross-selectivity. The recent advances of MIP technologies including the preparation protocols, applications and developments are discussed. Additionally, the performance of MIPs which can be improved by optimizing the composition of the polymeric network is reviewed regarding the characteristics of rebinding medium. The limitations of MIPs for water analysis, especially restricted selectivity for water soluble analytes, material wettability, and MIP inhomogeneity are discussed by providing the possible solutions. Finally, some novel applications and prospects for online, rapid and direct analysis of environmental samples using MIPs are included.

Preparation of dual-dummy-template molecularly imprinted polymers coated magnetic graphene oxide for separation and enrichment of phthalate esters in water

A novel molecularly imprinted polymers (MIPs) was prepared by the sol-gel imprinting method on the surface of magnetic graphene oxide (MGO) modified with mesoporous silica (mSiO2), with dipropyl phthalate (DPRP) and diisononyl phthalate (DINP) as the dual-dummy templates. The prepared MIPs, which was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), etc., was subsequently employed for simultaneous separation and enrichment of six typical phthalates esters (PAEs) in water. Moreover, the adsorption performance of MIPs was evaluated by means of adsorption isotherms, kinetics and selectivity experiments. Results demonstrated that the adsorption process followed the pseudo-second-order kinetic model, with an equilibrium time of about 120 min and the equilibrium adsorption capacities of MIPs for PAEs ranging from 2.3 to 4.8 mg g−1 at 298 K. Besides, the prepared MIPs exhibited favorable selectivity and reusability for PAEs. Furthermore, an analytical method was proposed for determining trace PAEs in water samples by gas chromatography/mass spectrometry (GC/MS) combined with solid-phase extraction (SPE) using MIPs as the adsorbent. Factors that affected the extraction efficiency of PAEs were also examined and optimized. It was found that the limits of detection (LODs) and the limits of quantity (LOQs) for PAEs were 0.01–0.05 μg L−1 and 0.05–0.2 μg L−1, respectively. The spiked recoveries for PAEs were >92.9%, with the relative standard deviations (RSDs) of <3.8%. Consequently, the synthesized MIPs can serve as a promising material for the selective detection and removal of PAEs from water.

Development of Molecularly Imprinted Polymers to Target Polyphenols Present in Plant Extracts

The development of molecularly imprinted polymers (MIPs) to target polyphenols present in vegetable extracts was here addressed. Polydatin was selected as a template polyphenol due to its relatively high size and amphiphilic character. Different MIPs were synthesized to explore preferential interactions between the functional monomers and the template molecule. The effect of solvent polarity on the molecular imprinting efficiency, namely owing to hydrophobic interactions, was also assessed. Precipitation and suspension polymerization were examined as a possible way to change MIPs morphology and performance. Solid phase extraction and batch/continuous sorption processes were used to evaluate the polyphenols uptake/release in individual/competitive assays. Among the prepared MIPs, a suspension polymerization synthesized material, with 4-vinylpyridine as the functional monomer and water/methanol as solvent, showed a superior performance. The underlying cause of such a significant outcome is the likely surface imprinting process caused by the amphiphilic properties of polydatin. The uptake and subsequent selective release of polyphenols present in natural extracts was successfully demonstrated, considering a red wine solution as a case study. However, hydrophilic/hydrophobic interactions are inevitable (especially with complex natural extracts) and the tuning of the polarity of the solvents is an important issue for the isolation of the different polyphenols.

Molecular imprinting sensor based on quantum weak measurement

A new type of sensing protocol, based on a high precision metrology of quantum weak measurement, was first proposed for molecularly imprinted polymers (MIP) sensor. The feasibility, sensitivity and selectivity of weak measurement based MIP (WMMIP) sensor were experimentally demonstrated with bovine serum albumin (BSA). Weak measurement system exhibits high sensitivity to the optical phase shift corresponding to the refractive index change, which is induced by the specific capture of target protein molecules with its recognition sites. The recognition process can be finally characterized by the central wavelength shift of output spectra through weak value amplification. In our experiment, we prepared BSA@MIP with modified reversed-phase microemulsion method, and coated it on the internal surface of measuring channels assembled into the Mach-Zehnder (MZ) interferometer based optical weak measurement system. The design of this home-built optical system makes it possible to detect analyte in real time. The dynamic process of the specific adsorption and concentration response to BSA from 5×10−4 to 5×10−1μg/L was achieved with a limit of detection (LOD) of 8.01×10−12g/L. This WMMIP shows superiority in accuracy, fast response and low cost. Furthermore, real-time monitoring system can creatively promote the performance of MIP in molecular analysis.