Facile Way to Prepare a Porous Molecular Imprinting Lock for Specifically Recognizing Oxytetracyclin Based on Coordination

Cupric ion coordination-mediated molecularly imprinted electrochemical sensor for the recognition and ratiometric detection of lidocaine

Molecularly imprinted polymers (MIPs) have been widely used as artificial recognition elements in sensing applications. However, their electrochemical sensing performance is generally hampered by limited affinity and uncontrolled condition change. In this work, a novel MIP electrochemical sensor based on metal coordination interaction was prepared and used for the recognition and ratiometric detection of lidocaine (LC). The sensor was constructed by electrodepositing Cu-coordinated MIP on biomass carbon modified glassy carbon electrode. Herein, Cu2+ ions acted as anchor for the immobilization of LC during the synthesis process, enabling the orderly formation of molecular recognition sites. Reversely, the metal coordination between Cu2+ ions and LC molecules facilitated the recognition of LC. Moreover, the doped cupric ions in the polymer film could provide a reference signal for subsequent ratiometric strategy. Thus the resulting sensor exhibited high selectivity, sensitivity, satisfactory reproducibility, and anti-interference ability. Under the selected conditions, the peak current ratio of LC and cupric ion was linear to LC concentration in the range of 0.008-2.5 μmol L-1 (R2 = 0.9951), and the limit of detection was 1.9 nmol L-1 (S/N = 3). The practical feasibility of the sensor was evaluated by detecting human serum and pharmaceutical samples, and satisfactory outcomes were obtained.

Design and fabrication of acorn-like Janus molecularly imprinted materials for highly specific separation and enrichment of oxytetracycline from restaurant oily wastewater

Molecularly imprinted polymer (MIP) is dedicated to the adsorption of target substances in the aqueous phase, but ignores the adsorption in a more complex environment (oily wastewater). In order to explore the application field of existing MIPs, acorn-like Janus particles were fabricated by photo-initiated seed swelling polymerization. A novel amphiphilic Janus-MIP was prepared with the acorn-like Janus particles as matrix, methacrylic acid, ethylene dimethacrylate and oxytetracycline (OTC) as functional monomers, crosslinking agents and template molecules via surface initiated-atom transfer radical polymerization (SI-ATRP). For comparison, the poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate) (poly (GMA-co-EDMA)) microspheres were also utilized as the matrix to prepare common spherical-MIP. The adsorption capacity of Janus-MIP for OTC was 23.8 mg g-1 in oil-water system, while the adsorption capacity of spherical-MIP for OTC was only 12.6 mg g-1 in the same system. At the same time, through high performance liquid chromatography (HPLC) analysis, Janus-MIP can specifically recognize and adsorb trace OTC in restaurant oily wastewater samples, and the proposed method exhibited a lower limit of detection (LOD, 3 ng mL-1) and a higher OTC recovery rate (94.2 %-98.4 %). This work demonstrated great potential for the detection and control of OTC contamination from real samples in an oil-water mixed environment.

Co2+ coordination-assisted molecularly imprinted covalent organic framework for selective extraction of ochratoxin A

Covalent organic frameworks (COFs) are attractive materials for sample pretreatment due to their tunable structures and functions. However, the precise recognition of contaminant in complex environmental matrices by COFs remains challenging owing to their insufficient specific active sites. Herein, we report Co2+ coordination-assisted molecularly imprinted flexible COF (MI-COF@Co2+) for selective recognition of ochratoxin A (OTA). The MI-COF@Co2+ was prepared via one-step polymerization of 3,3-dihydroxybenzidine, 2,4,6-tris(4-formylphenoxy)- 1,3,5-triazine, Co2+ and template. The flexible units endowed COFs with the self-adaptable ability to regulate the molecular conformation and coordinate with Co2+ to locate the imprinted cavities. The coordination interaction greatly improved the adsorption capacity and selectivity of MI-COF@Co2+ for OTA. The prepared MI-COF@Co2+ was used as solid phase extraction adsorbent for high-performance liquid chromatography determination of OTA with the detection limit of 0.03 ng mL-1 and the relative standard deviation of < 2.5 %. In addition, this method permitted interference-free determination of OTA in real samples with recovery from 89.5 % to 102.8 %. This work provides a simple way to improve the selectivity of COFs for the determination of hazardous compounds in complex environments.

Fabrication of molecularly imprinted carbon nanotubes integrating ionic liquids for efficient detection of perfluoroalkyl carboxylic acid in environmental water

It is extremely significant while challenging to accurately detect low-levels of perfluoroalkyl carboxylic acid compounds (PFCAs) in environmental water. Herein, adopting perfluorotetradecanoic acid as the dummy template, selective molecularly imprinted composites (CNTs@ILs@MIPs) grafted carbon nanotubes integrating hydrophilic ionic liquids were successfully prepared via surface imprinting and dummy-template imprinting techniques. The obtained CNTs@ILs@MIPs were applied as selective extraction adsorbent for specifically extract PFCAs in environmental water coupled with gas chromatography-mass spectrometry quantification. Detailed studies were conducted on the main preparation parameters and extraction conditions. The CNTs@ILs@MIPs displayed excellent adsorptivity, and the established method exhibited low LODs (0.60-1.64 ng L-1), wide linearity with R2 above 0.9994, and satisfactory adsorption recoveries (80.5-112.5%) for seven PFCAs. This proposed method provides a new applicable approach for the detection of targeted pollutants in environmental water by utilizing the high affinity and recognition ability of molecularly imprinted carbon nanotube functional materials modified with ionic liquids.

Magnetic molecularly imprinted polymer based on coordination for the determination of trace banned substance furosemide in human urine

Furosemide (FUR), banned in sports events by the World Anti-Doping Agency, is a key target in drug tests, necessitating a pretreatment material capable of selectively, rapidly, and sufficiently separating/enriching analytes from complex matrices. Herein, a metal-mediated magnetic molecularly imprinted polymer (mMIP) was rationally designed and synthesized for the specific capture of FUR. The preparations involved the utilization of chromium (III) as the binding pivot, (3-aminopropyl)triethoxysilane as functional monomer, and Fe3O4 as core, all assembled via free radical polymerization. Both the morphologies and adsorptive properties of the mMIP were characterized using multiple methods. The resulting Cr(III)-mediated mMIP (ChM-mMIP) presented excellent selectivity and specificity toward FUR. Under optimized conditions, the adsorption capacity reached 128.50 mg/g within 10 min, and the imprinting factor was 10.41. Moreover, it was also successfully applied as a dispersive solid-phase extraction material, enabling the detection of FUR concentration as low as 20 ng/mL in human urine samples when coupled with a high-performance liquid chromatography/photodiode array. Overall, this study offers a valuable strategy for the development of novel recognition material.

Current trends of functional monomers and cross linkers used to produce molecularly imprinted polymers for food analysis

Molecularly imprinted polymers (MIPs) as artificial synthetic receptors are in high demand for food analysis due to their inherent molecular recognition abilities. It is common practice to employ functional monomers with basic or acidic groups that can interact with analyte molecules via hydrogen bonds, covalent bonds, and other interactions (π-π, dipole-ion, hydrophobic, and Van der Waals). Therefore, selecting the appropriate functional monomer and cross-linker is crucial for determining how precisely they interact with the template and developing the polymeric network's three-dimensional structure. This study summarizes the advancements made in MIP's functional monomers and cross-linkers for food analysis from 2018 to 2023. The subsequent computational design of MIP has been thoroughly explained. The discussion has concluded with a look at the difficulties and prospects for MIP in food analysis.

Fabricating Ultrathin Imprinting Layer for Fast Capture of Valsartan via a Metal Affinity-Oriented Surface Imprinting Method

Rapid separation and enrichment of targets in biological matrixes are of significant interest in multiple life sciences disciplines. Molecularly imprinted polymers (MIPs) have vital applications in extraction and sample cleanup owing to their excellent specificity and selectivity. However, the low mass transfer rate, caused by the heterogeneity of imprinted cavities in polymer networks and strong driving forces, significantly limits its application in high-throughput analysis. Herein, one novel metal affinity-oriented surface imprinting method was proposed to fabricate an MIP with an ultrathin imprinting layer. MIPs were prepared by immobilized template molecules on magnetic nanoparticles (NPs) with metal ions as bridges via coordination, and then polymerization was done. Under the optimized conditions, the thickness of the imprinting layer was merely 1 nm, and the adsorption toward VAL well matched the Langmuir model. Moreover, it took just 5 min to achieve adsorption equilibrium significantly faster than other reported MIPs toward VAL. Adsorption capacity still can reach 25.3 mg/g ascribed to the high imprinting efficiency of the method (the imprinting factor was as high as 5). All evidence proved that recognition sites were all external cavities and were evenly distributed on the surface of the NPs. The obtained MIP NPs exhibited excellent selectivity and specificity toward VAL, with good dispersibility and stability. Coupled with high-performance liquid chromatography, it was successfully used as a dispersed solid phase extraction material to determine VAL in serum. Average recoveries are over 90.0% with relative standard deviations less than 2.14% at three spiked levels (n = 3). All evidence testified that the MIPs fabricated with the proposed method showed a fast trans mass rate and a large rebinding capacity. The method can potentially use high-throughput separation and enrichment of target molecules in batch samples to meet practical applications.

A novel electrochemical sensor based on a Cu-coordinated molecularly imprinted polymer and MoS2 modified chitin-derived carbon for selective detection of dextromethorphan

Dextromethorphan (DXM) is a widely utilized central antitussive agent, which is frequently abused by individuals seeking its recreational effect. But DXM overdose can cause some adverse effects, including brain damage, loss of consciousness, and cardiac arrhythmias, and hence its detection is significant. Herein, an electrochemical sensor based on a Cu-coordinated molecularly imprinted polymer (Cu-MIP) was fabricated for its detection. For constructing the sensor, nitrogen-doped carbon nanosheets (CCNs) were prepared through calcining chitin under an argon atmosphere, and molybdenum disulfide (MoS2) was allowed to grow on their surface. Subsequently, the obtained MoS2/CCNs composite was employed to modify a glassy carbon electrode (GCE), and the Cu-MIP was electrodeposited on the electrode in a Cu-1,10-phenanthroline (Cu-Phen) solution containing DXM, where Cu2+ played a role in facilitating electron transfer and binding DXM. Due to the large specific surface area, good electrocatalytic properties and recognition of the resulting composite, the resulting Cu-MIP/MoS2/CCNs/GCE showed high selectivity and sensitivity. Under optimized experimental conditions, the peak current of DXM and its concentration exhibited a good linear relationship over the concentration range of 0.1-100 μM, and the limit of detection (S/N = 3) was 0.02 μM. Furthermore, the electrochemical sensor presented good stability, and it was successfully used for the determination of DXM in pharmaceutical, human serum and urine samples.

Emerging biosensor probes for glycated hemoglobin (HbA1c) detection

Glycated hemoglobin (HbA1c), originating from the non-enzymatic glycosylation of βVal1 residues in hemoglobin (Hb), is an essential biomarker indicating average blood glucose levels over a period of 2 to 3 months without external environmental disturbances, thereby serving as the gold standard in the management of diabetes instead of blood glucose testing. The emergence of HbA1c biosensors presents affordable, readily available options for glycemic monitoring, offering significant benefits to small-scale laboratories and clinics. Utilizing nanomaterials coupled with high-specificity probes as integral components for recognition, labeling, and signal transduction, these sensors demonstrate exceptional sensitivity and selectivity in HbA1c detection. This review mainly focuses on the emerging probes and strategies integral to HbA1c sensor development. We discussed the advantages and limitations of various probes in sensor construction as well as recent advances in diverse sensing strategies for HbA1c measurement and their potential clinical applications, highlighting the critical gaps in current technologies and future needs in this evolving field.

The construction of highly selective surface molecularly imprinted polymers based on Cu(II) coordination for the detection of bisphenol A

Herein, we designed and constructed a highly selective MIPs for bisphenol A (BPA) named Cu-MIPs@CS based on Cu(II) coordination. The synthesis of Cu-MIPs@CS employed a dummy template strategy and surface imprinting technology, with chitosan (CS) as the substrate linked to imprinted layers via Cu2+ bridging. 4-vinylpyridine acted as the functional monomer, capable of forming a complex with the template ketoprofen, while ethylene glycol dimethacrylate served as the cross linker. Cu-MIPs@CS exhibited a significantly enhanced imprinting factor of 14.78 for BPA, which was approximately 6.6 times higher than that of imprinted materials without Cu2+ (MIPs@CS). Cu-MIPs@CS exhibited a selective factor of 12.74 towards resorcinol, which possessed identical functional groups but a smaller size than BPA, representing an enhancement of selectivity by 12.25-fold compared to MIPs@CS. More importantly, Cu-MIPs@CS exhibited a superior discrimination ability between BPA and its structural analogue, diphenolic acid, with an excellent selective factor of 2.93, highlighting its significance in distinguish the structural analogue of BPA. In contrast, MIPs@CS lack sufficient selectivity to differentiate between them. Through exploration of adsorption mechanism of Cu-MIPs@CS, it was demonstrated that the incorporation of Cu2+ significantly reduced nonspecific adsorption, but also facilitated the creation of more selective imprinted cavities by introducing metal coordination, thereby notably enhancing the selectivity of Cu-MIPs@CS. Finally, the developed Cu-MIPs@CS were applied as the solid phase extraction adsorbent and combined with HPLC-DAD detection to establish an analytical method towards BPA in drinking water samples. The limit of detection of the method was 0.14 μg L-1 and recoveries ranged from 95.6 % to 101 %. This work provided broad prospects for construction of highly selective MIPs and accurate quantification of trace amounts of BPA.

Exposure and risk assessment of phthalates in environmental water using a three-template molecularly imprinted fiber array strategy

Phthalate is a kind of environmental estrogen having a reproductive toxicity effect on animals and plants in the environment, and its detection is prone to matrix interference. Nevertheless, the molecularly imprinted polymer (MIP) can resist matrix interference. A three-template MIP solid-phase microextraction fiber array technique with improved adsorption flux and extraction capacity was innovatively developed. Additionally, the three-template MIP fiber arrays were used to screen phthalates in environmental water. The result showed that the three-template MIP fiber array had great potential for monitoring and controlling phthalate in environmental water. Moreover, the enrichment factors of the three-template MIP fiber arrays were 1410.65, 2419.55, and 493.21 times those of PA, PDMS, and PDMS/DVB commercial fiber-constructed arrays, respectively. The risk assessment using risk quotient revealed that BBP and DPHP had a medium-high ecological risk, DMP had a medium-low ecological risk, while EP and BP had a minimal ecological risk. This strategy represents an effective, easily tailored, and reusable method to simultaneously enhance extraction capacity and adsorption flux. It is environmentally friendly and has great feasibility for specific recognition of phthalate from environmental water and ecological risk assessment.

Preparation of lysozyme-imprinted mesoporous Zr-based metal-organic frameworks with remarkable specific recognition

The development of high-performance protein-imprinted materials remains challenging due to defects concerning high mass transfer resistance and non-specific binding, which are crucial for protein purification and enrichment. In this paper, lysozyme-imprinted mesoporous Zr-based MOF (mesoUiO-66-NH2@MIPs) with specific and selective recognition of lysozyme (Lyz) were prepared by surface imprinting technology. In particular, the excellent hydrophilicity mesoporous MOFs (mesoUiO-66-NH2) with a pore size of 10 nm was prepared as a carrier for Lyz immobilization by an auxiliary modulation strategy to regulate the microporous structure of UiO-66-NH2 with the propionic acid solution, enabling massive loading of the macromolecular protein Lyz. The mesoUiO-66-NH2@MIPs reached a maximum saturation adsorption of 206.54 mg g-1 on Lyz in 20 min at 25 °C with an imprinting factor of 2.57 and selection factors of 2.02, 2.34, and 2.45 for cytochrome c (Cyt c), bovine serum albumin (BSA) and bovine hemoglobin (BHb), respectively. More importantly, the mesoUiO-66-NH2@MIPs could specifically recognize Lyz from the mixed protein system. The adsorption capacity of Lyz could still reach 78.55% after 5 cycles with good cyclic regeneration performance. This provides a new research option for developing and applying novel porous MOF in biomolecule imprinting technology and the specific separation of biomolecules.

Efficient separation of aristolochic acid I from Caulis aristolochiae manshuriensis (Guan-mu-tong) with copper mediated magnetic molecularly imprinted polymer

Screening bioactive compounds from natural products is one of the most effective ways for new drug research and development. However, obtaining a single extract component on a large scale and with high purity from a complex matrix is still an arduous and challenging task. Herein, one metal mediated magnetic molecularly imprinted polymer (mMIP) was rationally designed and prepared for specifically capturing Aristolochic acid I (AAI). The preparation was done with copper(II) as binding pivot, (3-aminopropyl) triethoxysilane as functional monomer, and Fe3O4 as core, by a one-step sol-gel method. Under the optimized conditions, the apparent maximum binding amount of copper mediated mMIP (Cu-mMIP) reaches as high as 349.72 mg g-1, the highest among the reported AAI-MIPs. Moreover, the nanoparticles exhibit excellent specificity and selectivity, good reproducibility and stability, high superparamagnetism (60.32 emu g-1), and high imprinting efficiency (an imprinting factor of 7). By simulating an industrial-scale separation, 16.56 mg AAI (purity of 95.11%) is obtained after six cycles with 100 mg nanoparticles from 20 g Caulis aristolochiae manshuriensis (Guan-mu-tong). Notably, this takes only 3 hours and consumes 50 mL of methanol. The study provides a potent tool for the green, fast, and specific extraction of high-purity ingredients from natural plants in the manufacturing industry and conventional analysis in the lab.

Synergistically Enhancing Tumor Chemotherapy Using an Aggregation-Induced Emission Photosensitizer on Covalently Conjugated Molecularly Imprinted Polymer Nanoparticles

Due to the polygenic and heterogeneous nature of the tumorigenesis process, traditional chemotherapy is far from desirable. Fabricating multifunctional nanoplatforms integrating photodynamic effect can synergistically enhance chemotherapy because they can make the cancer cells much sensitive to chemotherapeutics. However, how to assemble different units in nanoplatforms and minimize side effects caused by chemodrugs and photosensitizers (PSs) still needs to be explored. Herein, a nanoplatform CPP/PS-MIP@DOX is developed using a simultaneously covalently conjugated new aggregation-induced emission (AIE) PS and a cell-penetrating peptide (CPP) on the surface of silica-based molecularly imprinted polymer (MIP) nanoparticles, prepared with doxorubicin (DOX) as the template in the water system via a sol-gel technique. CPP/PS-MIP@DOX has good biocompatibility, high DOX-loading ability, promoted cellular uptake, and sustained and pH-sensitive drug release capability. Furthermore, it can efficiently penetrate into tumor tissue, accurately home to, and accumulate at the tumor site. As a result, a better efficacy with lower cytotoxicity is achieved with a smaller dosage of DOX by utilizing either the photodynamic effect or unique characteristics of the MIP. It is the first nanoplatform fabricated by chemically conjugating AIE PSs directly on the surface of the scaffold via the surface-decorated strategy and successfully applied in cancer therapy. This work provides an effective strategy by constructing AIE PS-based cancer nanomedicines with MIPs as scaffolds.

Generic imprinted fiber array strategy for high-throughput and ultrasensitive simultaneous determination of multiple neonicotinoids

Herein, a new generic fiber array based on molecular imprinting solid-phase microextraction (MIP-SPME) technology, was described to enrich trace multiple neonicotinoids with high flux from the food matrix. To begin with adsorption experiments coupled with theoretical calculations provided universal means for selecting the preferred template molecule clothianidin (CLT). Results demonstrated that the CLT-MIP fiber array exhibited significantly superior enrichment ability of 1189-2356-folds for six neonicotinoids compared with two kinds of commercial fiber arrays. Furthermore, the practicability of the CLT-MIP fiber array was verified by simultaneously determining multiple neonicotinoids in tea and honey samples. The CLT-MIP fiber array showed a limit of detection (LOD) of 0.03-0.58 μg/L for six neonicotinoids. The method also exhibited satisfactory recoveries ranging from 85.4% to 116.8% with RSD (n = 3) less than 8.8%. The imprinted fiber array has the advantages of high-throughput, predominant reproducibility, and accurate quantitation multi-component, and it may open up a new mean to efficiently enrich high-throughput and simultaneously detect multiple compounds from food samples.

Adsorption properties and recognition mechanisms of a novel surface imprinted polymer for selective removal of Cu(II)-citrate complexes

Cu(II)-citrate (Cu(II)-CA) complex, as one of the components in plating solutions, increases the difficulty of Cu(II) treatment due to its stable structure and high mobility. In this work, a novel surface imprinted polymer (Cu-CA-SIP) for selective removal of Cu(II)-CA complex from aqueous solution is synthesized by using polyethyleneimine (PEI) grafted onto chloromethylated polystyrene (CMP) microspheres. Cu(II)-CA anions are successfully imprinted with the molar ration of 1:1 by Cu-CA-SIP at initial pH 4.0. Nearly 100% removal rate can be achieved even at low Cu(II)-CA concentration (0.5 mmol/L), and the maximum Cu(II) uptake of Cu-CA-SIP reaches 1.38 mmol/g at 303 K. In Cu(II)/Fe(III)-CA, Cu(II)/Ni(II)-CA, Cu(II)/Zn(II)-CA and Cu(II)/Cd(II)-CA systems, the relative selectivity coefficients of Cu-CA-SIP for Cu(II)-CA are 9.66, 2.32, 1.40 and 44.55, respectively. Moreover, Cu-CA-SIP can be retrieved with negligible loss of adsorption capacity after six times of reuse. The Cu-CA-SIP column can effectively treat the actual electroplating wastewater within 114 BV, and can still reach 104 BV after three dynamic cycles. Therefore, an innovative imprinted material is designed for the first time on the basis of coordination-configuration recognition mechanism for the treatment of electroplating wastewater, providing a new insight in developing surface imprinted polymer in environmental remediation.

One-Pot Strategy as a Green and Rapid Method to Fabricate Magnetic Molecularly Imprinted Nanoparticles for Selective Capture of Sulfonylurea Herbicides

Magnetic solid-phase extraction (MSPE) based on molecularly imprinted nanoparticles (MINs) has attracted wide attention in sample pretreatment because it combines the merits of high selectivity and quick extraction procedures. However, laborious, time and solvent-consuming steps were involved in the synthesis of magnetic imprinted particles in existing approaches. To circumvent this dilemma, a green and rapid "one-pot" strategy was proposed to prepare MINs. Halosulfuron-methyl (HSM) was selected as a template molecule, and Gaussian 09 simulation software was employed to screen the 2,4,6-trivinylboroxin pyridine complex (TBP) as a functional monomer. Subsequently, the fabrication was simply conducted using a hydrothermal approach by mixing self-assembly solution of TBP-HSM, Fe³⁺, Fe²⁺, dimethyl sulfoxide, and azobisisobutyronitrile in one-pot with a total reaction time of 3.0 h. Various characterized results well evidenced the successful imprint of HSM and the resultant HSM-MINs presented satisfying superparamagnetism and saturation magnetism. Under the optimized parameters, the obtained HSM-MINs displayed good recognition capability and selectivity toward HSM (recognition coefficient was 2.60), as well as a satisfactory saturation adsorption capacity (1781 μg/g). The quantification of sulfonylurea herbicides at trace levels in environmental water and soil samples was selected as a paradigm to demonstrate the practicality and reliability of HSM-MINs/MSPE. The present study provides a convenient, reliable, and green approach for fabricating a magnetic molecular-imprinting adsorbent for MSPE.