Molecularly Imprinted Membranes Research Articles

Precise selection and separation of ribavirin by nanoconfined imprinted MOFs membrane

Metal-organic frameworks (MOFs) are highly tunable materials with potential as porous media in membrane separations. However, traditional MOFs are usually not specific and selective. Here, we demonstrate a nanocomposite molecularly imprinted MOFs membrane material that can selectively adsorb and separate specific molecules. We demonstrated this adsorption-separation mechanism by introducing ribavirin molecules into multicomponent MOFs by molecular imprinting strategy and performing permeation and dynamic permeation tests. Due to the previously formed nanocages with a specific structure inside the MOFs, combined with the synergistic effect of the subsequent secondary imprinting, excellent selectivity (more than 6) and effective adsorption (46.46 mg g−1) were displayed by the obtained imprinted membrane. The stability of the membrane was measured by the process of dynamic osmosis, and the results showed that the membrane always had a large factor of separation (greater than 7). The experimental results and conclusions of this paper provide new theoretical and practical support for solving the key scientific issues of the “trade-off” effect between the permeation flux and permeation selectivity of template molecules in the traditional molecularly imprinted membranes (MIMs) osmotic separation process.

Molecularly imprinted alginate-PVP membrane for the selective fluorescence detection of flavonoids in foods: A practical case for rutin

Flavonoids benefits have rendered them interesting molecules in the realm of sensing. However, a significant challenge lies in their selective and sensitive detection in complex matrices. One of the most relevant flavonoids is rutin (RU), a flavonoid glycoside. In this work, a novel, straightforward, and green approach is proposed to prepare a selective molecularly imprinted membrane (MIM) for RU based on sodium alginate and polyvinylpyrrolidone, following a central composite design for the optimization of the MIM preparation. The developed membrane was characterized by Fourier transform infrared spectroscopy, thermo-gravimetric analysis, and scanning electron microscopy to assess the functional, thermal, and morphological properties of the membrane, respectively. The developed MIM was successfully applied for the selective and sensitive solid spectro-fluorescence sensing of RU within a concentration range of 0.01–10 µg/mL and a limit of detection (LOD) of 3.6 ng/mL. Furthermore, a new 3D-printed smartphone accessory was designed and applied in smartphone-based solid fluorescence assays. This innovation enabled portable, label-free, rapid, cheap, and green detection of RU across a concentration interval of 0.05–10 µg/mL, with a LOD of 20 ng/mL. Moreover, MIM showed important long-term stability and good reusability (10 regeneration cycles). Finally, the proposed methodology was validated using an accuracy statistical approach. Overall, this study didn’t only demonstrate an innovative and straightforward approach to imprinting technology but also highlighted the promise of the proposed smartphone-based sensing method as a versatile tool with a broad range of applications to automatize the analysis and to enhance portable diagnosis technology.

Development of a molecularly imprinted membrane for selective, high-sensitive, and on-site detection of antibiotics in waters and drugs: Application for sulfamethoxazole

Sulfonamides are among the widespread bacterial antibiotics. Despite this, their quick emergence constitutes a serious problem for ecosystems and human health. Therefore, there is an increased interest in developing relevant detection method for antibiotics in different matrices. In this work, a straightforward, green, and cost-effective protocol was proposed for the preparation of a selective molecularly imprinted membrane (MIM) of sulfamethoxazole (SMX), a commonly used antibiotic. Thus, cellulose acetate was used as the functional polymer, while polyethylene glycol served as a pore-former. The developed MIM was successfully characterized through scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The MIM was used as a sensing platform in conjunction with a smartphone for optical readout, enabling on-site, selective, and highly sensitive detection of SMX. In this way, a satisfactory imprinting factor of around 3.6 and a limit of detection of 2 ng mL−1 were reached after applying response surface methodologies, including Box-Behnken and central composite designs. Besides, MIM demonstrated its applicability for the accurate and selective detection of SMX in river waters, wastewater, and drugs. Additionally, the MIM was shown to be a valuable sorbent in a solid-phase extraction protocol, employing a spin column setup that offered rapid and reproducible results. Furthermore, the developed sensing platform exhibited notable regeneration properties over multiple cycles and long shelf-life in different storage conditions. The newly developed methodology is of crucial importance to overcome the limitations of classical imprinting polymers. Furthermore, the smartphone-based platform was used to surpass the typically expensive and complicated methods of detection.

Synthesis of metal-organic framework hybrid nanocomposites based on MOFs@C3N4 with high selective separation ability for luteolin

Complex substrates found in certain extracts-particularly those containing high phenolic compounds with significant medicinal value-pose considerable challenges to developing molecularly imprinted membranes (MIMs) with specific recognition abilities. In this study, UiO-66-NH2, a metal–organic structure (MOF), was chosen as an optimizer to enhance the basic support material C3N4. A composite imprinted membrane based on MOFs was then prepared for the targeted adsorption of luteolin (LTL). This not only increases the surface area and pore capacity of the composite membranes, but also ensures unprecedented control over the membranes structure and good stability. To maximize the proportion of imprinted sites, we utilize an advanced boron affinity sol–gel imprinting technique that capitalizes on the exceptional response of the bifunctional monomer. By finely manipulating the imprinting process, controlled distribution of imprinted sites was achieved. Furthermore, the incorporation of Ag nanoparticles into the composite matrix of MIMs enhances selectivity and efficiency due to their plasmonic properties and high affinity for phenolic compounds, providing increased adsorption surface area and additional binding sites. The results showed satisfactory rebinding ability (56.25 mg g−1) and superselective (βAG/LTL = 4.43 and βCT/LTL = 8.49). It was worth noting that incorporating Ag nanoparticles into composite MIMs for the selective adsorption of LTL demonstrates significant potential. This includes enhanced selectivity, efficiency, and hydrophilicity of the membrane surface. Thus, enhanced hydrophilicity can establish stronger non-covalent interactions, namely hydrogen bonding and van der waals forces, with the target molecules, thereby significantly improving the adsorption capacity of the MIMs. The feasibility of this method was demonstrated via in-situ infrared analysis of the chemical structure changes before and after adsorption.

Porous MOFs-based self-assembled membrane with specific rebinding nanocages for selective recognition and separation at molecular level

We present the design and fabrication of high-performance molecularly imprinted membranes (MIMs) using a UiO-66@PDA framework with densely imprinted sites for the targeted adsorption of artemisinin (ATSN). UiO-66@PDA was synthesized by modifying polydopamine with metal-organic frame (MOF) that contain Zr(IV) ions. The unique UiO-66@PDA structure exhibits an excellent specific surface area and strong binding abilities towards ATSN due to the abundant phenolic, quinone, and amino functional groups. The addition of SiO2 nanoparticles further enhanced the stability of the hybrid membrane during the adsorption process, and the preparation of inorganic-organic hybrid membranes (k-SUPCP-IMs) involves the use of a click chemistry-based imprinted polymer that takes advantage of the heterogeneous structure of the material. This process highlights the importance of different building blocks and functional reactions in controlling the morphology and porosity of porous organic polymers. The results showed satisfactory rebinding ability (40.07 mg g−1) and superselective (βATMT/ATSN = 7.87, βDDTM/ATSN = 8.26, βATST/ATSN = 6.40). It was noteworthy that the unique electrostatic interaction between SiO2 and the imprinted molecules provides optimal conditions for the formation of high-affinity binding sites, thereinto, the creation of additional active sites played a critical role in improving the sensitivity of MIMs.

An anti-fouling wearable molecular imprinting sensor based on semi-interpenetrating network hydrogel for the detection of tryptophan in sweat

The challenge of heavy biofouling in complex sweat environments limits the potential of electrochemical sweat sensors for noninvasive physiological assessment. In this study, a novel semi-interpenetrating hydrogel of PSBMA/PEDOT:PSS was engineered by interlacing PEDOT:PSS conductive polymer with zwitterionic PSBMA network. This versatile hydrogel served as the foundation for developing an anti-fouling wearable molecular imprinting sensor capable of sensitive and robust detection of tryptophan (Trp) in complex sweat. The incorporation of PEDOT:PSS conductive polymer into the semi-interpenetrating hydrogel introduced diverse physical crosslinks, including hydrogen bonding, electrostatic interactions, and chain entanglement. This incorporation considerably boosted the hydrogel's mechanical robustness and imparted commendable self-healing property. At the same time, the synergistic coupling between the well-balanced charge of the zwitterionic network and the high conductivity of the PEDOT:PSS polymer facilitated efficient charge transfer. The formation of the desired molecular imprinting membrane of semi-interpenetrating hydrogel was triggered by self-polymerization of dopamine (DA) in the presence of Trp. The designed biosensor demonstrated good sensitivity, selectivity and stability in detecting the target Trp. Notably, it also exhibited exceptional anti-fouling abilities, allowing for accurate Trp detection in complex real sweat samples, yielding results comparable to commercial enzyme-linked immunoassay (ELISA).

Synthesis of Molecularly Imprinted Membrane Glucose for Selective Membrane Transport

Molecularly Imprinted Membrane (MIM) was synthesized using polyeugenoxy acetic acid as the functional polymer, polyethylene glycol as the crosslinker agent, and polysulfone as a base membrane which was applied as a selective glucose membrane transport, and the immersion time expected to determine the transport capability of the membrane. This study aimed to determine the selectivity and transport properties of the MIM and NIM membranes. NIM was used as a control for MIM to research the selectivity test. In comparison, MIM has a template, while NIM is without a template. In this study, eugenol derivatives were synthesized through a polymerization reaction using a BF3-diethylether catalyst polymerized for 16 hours to produce polyeugenoxy acetic acid (PA). The PA was contacted with 7500 ppm glucose. PA-glucose produced an imprinted membrane, while PA produced a non-imprinted membrane. The membrane thickness was measured with a micrometer, resulting in a measurement range of 0.08–0.10 mm. The best transport result was achieved at the membrane passage of 24 hours of immersion time because the effect of membrane immersion time can increase the porosity, hydrophilicity, and membrane’s transport ability. Transport with MIM membrane shows better and more selective results than NIM. This confirms the existence of a glucose template on the MIM membrane, which causes the MIM membrane to recognize glucose and transport glucose better than fructose. This study’s advantages include learning how immersion time affects membrane production and determining how well MIM and NIM membranes transport and select glucose and fructose. Furthermore, membrane characterizations were done using FTIR to identify functional groups, SEM-EDX to analyze the shape of the membrane, and a UV-Vis spectrophotometer to analyze the membrane’s selectivity and transport capabilities.

Advanced Development of Molecularly Imprinted Membranes for Selective Separation.

Molecularly imprinted membranes (MIMs), the incorporation of a given target molecule into a membrane, are generally used for separating and purifying the effective constituents of various natural products. They have been in use since 1990. The application of MIMs has been studied in many fields, including separation, medicine analysis, solid-phase extraction, and so on, and selective separation is still an active area of research. In MIM separation, two important membrane performances, flux and permselectivities, show a trade-off relationship. The enhancement not only of permselectivity, but also of flux poses a challenging task for membranologists. The present review first describes the recent development of MIMs, as well as various preparation methods, showing the features and applications of MIMs prepared with these different methods. Next, the review focuses on the relationship between flux and permselectivities, providing a detailed analysis of the selective transport mechanisms. According to the majority of the studies in the field, the paramount factors for resolving the trade-off relationship between the permselectivity and the flux in MIMs are the presence of effective high-density recognition sites and a high degree of matching between these sites and the imprinted cavity. Beyond the recognition sites, the membrane structure and pore-size distribution in the final imprinted membrane collectively determine the selective transport mechanism of MIM. Furthermore, it also pointed out that the important parameters of regeneration and antifouling performance have an essential role in MIMs for practical applications. This review subsequently highlights the emerging forms of MIM, including molecularly imprinted nanofiber membranes, new phase-inversion MIMs, and metal-organic-framework-material-based MIMs, as well as the construction of high-density recognition sites for further enhancing the permselectivity/flux. Finally, a discussion of the future of MIMs regarding breakthroughs in solving the flux-permselectivity trade-off is offered. It is believed that there will be greater advancements regarding selective separation using MIMs in the future.

Novel graphene electrochemical transistors incorporating zirconia inorganic molecular imprinted layer：Design, construction and application for highly sensitive and selective detection of acetaminophen

Owing to their intrinsic amplifying effect together with chemical stability, graphene electrochemical transistor sensors (GECTs) are gaining momentum for sensing applications. However, the surface of GECTs for different detection substances must be modified with different recognition molecules, which was cumbersome and lack a universal method. Molecularly imprinted polymer (MIP) is a kind of polymer with specific recognition function for given molecules. Here, MIP and GECTs were combined to effectively solve the problem of weak selectivity of GECTs, and achieve the high sensitivity and selectivity of MIP-GECTs equipment in detecting acetaminophen (AP) in complex urine environment. A novel molecular imprinting sensor based on Au nanoparticles modified zirconia (ZrO2) inorganic molecular imprinting membrane on reduced graphene oxide (ZrO2-MIP-Au/rGO) was proposed. ZrO2-MIP-Au/rGO was synthesized by one-step electropolymerization using AP as template, ZrO2 precursor as the functional monomer. The –OH group on ZrO2 and the –OH/–CONH– group on AP were easily bonded by hydrogen bonding to form a MIP layer on the surface, which allows the sensor to have a large number of imprinted cavities for AP specific adsorption. As a proof of method, the GECTs based on ZrO2-MIP-Au/rGO functional gate electrode has the characteristics of wide linear range (0.1 nM-4 mM), low detection limit (0.1 nM) and high selectivity for AP detection. These achievements highlight the introduction of specific and selective MIP to GECTs with unique amplification function, which could effectively solve the problem of selectivity of GECTs in complex environments, suggesting the potential of MIP-GECTs in real-time diagnosis.

Hydrophilic imprinted MnO2 nanowires “coating” membrane with ultrahigh adsorption capacity for highly selective separation of Artemisinin/Artemether

The selective separation and purification of ART and ARE using molecularly imprinted membrane (MIM) has attracted considerable attention, but most of conventional blending MIM face low adsorption capacity and poor selectivity due to the blockage of imprinting sites. Herein, an alternative ART imprinted MnO2 nanowires “coating” membrane (MINM) withhydrophilicity was fabricated by vacuum filtration of imprinted MnO2 nanowires and graphene oxide nanosheets on PVDF membrane surface for selective ART separation. For the MINM, the imprinted MnO2 nanowires coating offers more available exposed imprinting sites on the MINM surface compared to that of the blending MIM, while the introduction of graphene oxide improves the hydrophilicity of MINM, significantly reducing the non-specific absorption. Consequently, the MINM exhibits ultrahigh ART adsorption capacity and selectivity, with the ART adsorption amount of 335 mg g−1 at 5 min using dynamic cross-flow separation system, about 12.18 times higher than that of ARE (27.5 mg g−1), and the separation factor (a) value of 12.39. Moreover, the ATR FT-IR dynamic spectrum discloses the in-situ formation of H-bond between ART and MINM, playing a key role in the selective adsorption process. This work provides an alternative strategy to prepare “coating” MIM for high-efficient and selective separation of complex analogue systems.

Determination of ribavirin by molecularly imprinted electrochemical sensors using pyrro-1-propionyl-alaninoyl-chitooligosaccharide and pyrrole as bifunctional monomers on Prussian blue-gold nanocomposite films

Herein, we developed a highly sensitive imprinted electrochemical sensor for the trace detection of ribavirin (RBV) using pyrrole (PYR) and pyrro-1-propionyl-alaninoyl-chitooligosaccharides (PPACO) as bifunctional monomers on Prussian blue-gold nanocomposite films. PPACO had strong molecular effect on RBV molecule and was selected by quantitative calculations. After the deposition of the Prussian blue-gold nanocomposite on a glassy carbon electrode (GCE) surface, a 4-aminothiophenol layer successfully self-assembled on the surface. Subsequently, the molecularly imprinted membrane (MIM) was subjected to electrochemical polymerization on the electrode surface using RBV as the template and PPACO and PYR as the two monomers. After eluting the RBV molecules from the MIM, the fabricated RBV-MIM/Fn-Au-PB/GCE exhibited the specific adsorption of RBV. Under optimal conditions, differential pulse voltammetry (DPV) was used to measure the performance of the synthesized sensor, which exhibited a linear relationship between the decreasing peak current and RBV concentration from 0.015 to 3.5 μM with a low detection limit of 3 nM (S/N = 3). As a proof of concept, RBV-MIM/Fn-Au-PB/GCE was also applied to monitor the RBV content in RBV granules. It showed a satisfactory recovery (96.5–99.2%) with a relative standard deviation of less than 3.5% (n = 5), and thus, we believe it has potential for practical applications.

“Sandwich-like” electrospinning fiber-based molecularly imprinted membrane constructed with electrospun polyethyleneimine as the multifunction interlayer for the selective separation of shikimic acid

Electrospinning fiber with excellent structure is sharing the spotlight with molecularly imprinted membranes (MIMs) in the selective separation field. This work shows a teamed boronate affinity (TBA)-functionalized electrospinning fiber-based MIM with designed binding sites for shikimic acid (SA). Electrospun polyacrylonitrile (PAN) fiber is used as the supporting material. Specifically, polyethyleneimine (PEI)-PAN interlayer is constructed on the PAN substrate via electrospinning instead of chemical grafting. The role of PEI-PAN interlayer is compared with the PEI-grafting membrane as well as separation performance. The introduction of PEI via electrospinning enhances the adhesion between PAN substrate and imprinted layer, additionally, offers abundant reaction sites for more boronic acid moieties to decrease the pKa value of boronic acid. The “sandwich-like” SA molecular imprinted PAN membrane (S-MIPM) exhibits perfect integrity, excellent pore structure and enhanced selective adsorption performance. The adsorption amount of S-MIPM is 68.64 mg g−1 under neutral condition and 1413 L m−2h−1 bar−1 for the pure water flux. S-MIPM exhibits 3.1 times higher of adsorption capacity than that of the membrane prepared via chemical grafting, demonstrating the advantage of the proposed strategy. The membrane shows good selective permeation ability, which may give a better direction for the selective separation of 1,2-diols by boronate affinity.

Hierarchically porous molecularly imprinted membranes with multiple transfer channels for micropollutants selective separation

Molecularly imprinted membranes (MIMs) have been considered as a promising material for the treatment of intractable micropollutants due to their predetermined selectivity and high stability. Herein, we proposed an exclusive design by incorporation of heterogeneous porous UiO-66-NH2 and hierarchically porous structure nanofibrous membranes to fabricate a MOFs based hierarchically porous molecularly imprinted nanofiber membranes (HP-MINMs) with multiple mass transfer channels, achieving efficient selective removal of atrazine (ATZ). The heterogeneous pores UiO-66-NH2 nanoparticles as matrix facilitated loaded with more densely and accessible imprinted recognition sites. Meanwhile, the multiple transfer channels formed in well-designed hierarchically porous nanofibrous membranes significantly enhancing of permeation flux and increase the contacting efficiency of target molecules with selective recognition sites. As a result, the obtained HP-MINMs possess synchronous enhanced permeation flux (J = 0.40 × 10−3, 1.01 × 10−3 and 1.07 × 10−3 mg min −1 cm −2) and permselectivity factors (β = 3.22 and 3.52), which much superior to those pure molecularly imprinted nanofiber membranes and other references. Importantly, the impressive selective separation performance (the separation efficiency for ATZ is 60.7 %) was achieved in continuous separation process. The presented work provides a fresh idea for addressing the trade-off effect in selective separation of MIMs.

“Cobweb locking raindrops” inspired construction of bio-based 3D porous molecularly imprinted membrane with ultrahigh adsorption capacity and selectivity: Effectively avoiding imprinting sites embedment

Generally, 2D “thin-film” structural molecularly imprinted membranes (MIMs) prepared by the common phase inversion method suffer low adsorption capacity due to the easy embedment of imprinting sites. Herein, an alternative “delayed phase inversion” strategy was first developed to construct a natural loofah-based 3D porous MIM (LPMIM), in which the as-prepared molecularly imprinted polymers (MIPs) with artesunate (ARU) as dummy template spontaneously interacted with the polyvinylidene fluoride (PVDF) pre-treated loofah framework (LPM), and evenly anchored on loofah fiber surfaces, similar to the cobweb locking raindrops. Interestingly, the natural 3D fiber cross networks of loofah not only provided sufficient capacity and space to support MIPs without causing aggregation and maintains high flux, but also the inherent high mechanical strength of loofah fibers endowed the LPMIM with excellent stability. Under dynamic conditions the ART adsorption capacity of LPMIM could be further remarkably improved by tailoring the flow rate of 1.19 mL·cm−2·min−1, up to 334.70 mg/g. As a result, effective enhancement in the artemisinin (ART) adsorption capacity were achieved for the LPMIM, which was about 2.25 times higher than that of the common blend MIM prepared by common phase inversion method (148.30 mg/g). Moreover, the LPMIM possessed high ART selectivity towards its analogue, artemether (ARE), giving an ART/ARE ratio of 2.7. Furthermore, the LPMIM displayed excellent recycling performance. By altering the template of MIPs, the corresponding LPMIM can be expanded to highly selective separation of other substrates along with large absorption capacity. This work highlights a universal strategy to construct novel MIMs with high absorption capacity and selectivity using bio-based fiber cross frameworks.

Highly Improved Chiral-Selective Resolution in Pillar[5]arene-Functionalized Molecularly Imprinted Membranes

It is a challenging task to achieve the effective separation of chiral compounds under simple and rapid conditions. In order to solve this problem, this study used the molecularly imprinted membrane (MIM) technology developed on the basis of biological semi-permeable membranes, using S-triadimefon as the template molecule, and successfully prepared MIMs by photo-initiated polymerization. By adding macrocyclic molecular 1,4-bis(allyloxy)pillar[5]arene as a functional monomers, the effectiveness of the chiral recognition sites of the target molecules is improved, thereby improving the chiral selectivity of the MIM and optimizing the molar ratio of template molecules, monomers, and cross-linkers. On this basis, the separation effect of non-MIM (NIM), single-monomer MIM (MIM-I), and two-monomer MIM (MIM-II) on triadimefon enantiomers was investigated. It was found that the enantiomer excess (e. e.) % value of MIM-I is larger than that of NIM, but the value of MIM-I is still very low. When pillar[5]arene, a macrocyclic molecule was added as the second monomer, its e. e. % increased from 27.4 to 84.8%.

Silk fibroin/calcium alginate composite modifying supermacroporous molecularly imprinted membrane synthesis for high performance on recognizing bovine hemoglobin

AbstractBio‐macromolecule hemoglobin (Hb) is a kind of iron‐rich metalloprotein that abundant in erythrocytes with various physiological properties. Separating Hb from bio‐matrix with high efficacy is crucial to Hb application but quite challenging. In this study, a supermacroporous molecularly imprinted membrane (MIM) was prepared with high performance on recognizing bovine hemoglobin (BHb). By using the silk fibroin and calcium alginate as mechanical modifiers, the mechanical strength of the prepared membrane was significantly improved to at around 0.25 MPa, and the supermacroporous structure in MIM was also formed. The MIM adsorption capacity of BHb was as high as 121.8 mg g−1at the initial concentration of 0.5 mg mL−1. The MIM separation factor of BHb from BHb/BSA mixtures was as high as 7.34, and the relative imprinting factor was at around 4.0. The prepared MIM demonstrated the superiority and the valuable application prospect on specific separation of BHb.

Bio-inspired design on EGCG-selective membrane: An anchoring/imprinting strategy based on bi-interactions

In recent years, molecularly imprinted membrane (MIM) has exhibited superiority in industrial separation, drug purification, solid-phase extraction and even medical detection owing to its remarkable selectivity. For catechins, however, the reactivity with free radicals limits the traditional construction of MIM towards such molecules. Here in this work, we have developed a bio-inspired MIM towards Epigallocatechin gallate (EGCG, a representative catechin) by the anchoring/imprinting strategy. The covalent interactions based on boronate-affinity supplied an oriented anchoring effect, while the non-covalent interactions from l-cysteine promoted the formation of imprinted sites that are highly matched with template. Mild and efficient imprinting was carried out by self-polymerization of dopamine to avoid the destruction of templates. As a result, remarkable selectivity coefficients (2.70 and 4.58), permselectivity coefficients (more than 3.19 and 3.41) and separation factors (5.18 and 7.00) were achieved on the EGCG-imprinted membrane (EIM), accompanied by the impressive imprinting factor (10.14) and superior regeneration performance (only 4.4% of the decline in five cycles). For deep insight into selective recognition and separation, microscopic and visualized mechanisms of site formation and specific rebinding was proposed by molecular dynamics simulations. Approaches with such an anchoring/imprinting strategy will enrich the avant-garde molecular imprinting strategies, and also expand membrane-based applications.

Bio-synthesis of molecularly imprinted membrane with photo-regeneration availability for selective separation applications

Since the in-depth exploration of molecularly imprinted membranes (MIMs), compatibility between high selectivity and superior regeneration has been always the focus. Here we propose, based on biomimetic self-polymerization of dopamine, highly specific, self-cleaning, and interfacial-stable g-C3N4/Ag3PO4/PDA-composited molecularly imprinted membranes (C/A/D-MIMs) for enhanced treatment of fit-for-purpose water. Ciprofloxacin (CFX) was selected as a representative target because of its potential toxic effect on the microorganism, which will inevitably weaken the traditional biological-based water treatment. Besides superior antifouling performance, remarkable permselectivity (βNFX/CFX = 1.65, βEFX/CFX = 1.90, and βOFX/CFX = 2.08) and flux regeneration rate (84.4% after photo-regeneration) could be ascribed to (i) effective formation of molecularly imprinted sites by self-polymerization of dopamine, (ii) synergism of polydopamine in constructing Z-scheme heterojunction configuration, as well as (iii) bio-adhesion of polydopamine in coupling photocatalyst and MIMs. Achievements in the present work will promote the development of highly specific and self-cleaning MIMs with considerable stability and applications in specific and selective separation.

Hydrophilic molecularly imprinted membranes based on GO-loading for simultaneously selective recognition and detection of three amphenicols drugs in pork and milk

It plays an important role to effective detection of amphenicols antibiotic residues in food and an important issue considering of possible impact on human health. In this work, the molecularly imprinted membranes (MIMs) were proposed to simultaneously recognize and detect thiamphenicol (TAP), florfenicol (FF) and chloramphenicol (CAP) in pork and milk samples. The synergistic effect of graphene oxide (GO), double functional monomer (methacrylate and acrylamide) and “click chemistry” strategy prompted the membranes to possess good surface hydrophilicity (48.6°), excellent selectivity and capacity to exclude macromolecules. The theoretical models of selectivity mechanism showed the selective recognition depended mainly on the hydrogen bond interaction and van der Waals interaction between the analytes and monomers. The limit of detection for 3 analytes were 0.04–0.28 µg kg−1, and showed a good correlation (r > 0.9949). Finally, this study established an effective MIMs-UHPLC-MS/MS method with great potential for the monitor of antibiotics residue in complicated matrices.

Progress of molecular imprinting technique for enantioseparation of chiral drugs in recent ten years

The existence of chiral compounds is a very common phenomenon in the field of medicine, and nearly 60% of drugs are chiral. The separation of racemic drugs is the key to safe use of drugs. Molecularly imprinted technique (MIT) has attracted wide attention in the separation of chiral drugs in recent years due to its simple operation and strong specific recognition ability of target molecules. Molecularly imprinted polymers (MIPs) have been used as selective adsorbents in a variety of analytical techniques, and excellent progress has been made in the separation of chiral drugs. In this paper, the MIT for the separation of drug in recent ten years is reviewed. We will introduce how to achieve chiral drug resolution in different chromatographic techniques based on the morphological differences of MIPs (micron-sized particles, nanoparticles and monolithic column materials) as the classification criteria. Furthermore, the contributions of surface molecularly imprinted technique (SMIT) and molecularly imprinted membrane (MIM) technology in racemic drug resolution are also introduced. Finally, the main application challenges of chiral MIT are briefly introduced, and the future development direction of this field is prospected.