Synthesis of magnetic covalent organic framework molecularly imprinted polymers at room temperature: A novel imprinted strategy for thermo-sensitive substance

Imprinted covalent organic frameworks solid-phase microextraction fiber for in vivo monitoring of acidic per- and polyfluoroalkyl substances in live aloe

Per- and polyfluoroalkyl substances (PFASs) can lead to risks associated with animal and human health through the transfer along food chains. It is confirmed that PFASs can be transported to each part of plants after taken up by the roots. To better elucidate the underlying mechanisms for such exposure, it is highly valuable to develop analytical capabilities for in vivo monitoring of PFASs in live plants. In this work, a novel imprinted covalent organic frameworks (CMIP) solid-phase microextraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry was developed with low limits of detection for six acidic PFASs (0.1-0.3 ng g-1) and used for in vivo monitoring in live aloe. The CMIP coating shows good precision (RSD of intra and inter ≤9.6 % and 10.2 %, respectively) and possesses much higher extraction efficiency than the commercial coatings. After cultivating aloe in soil spiked PFASs, the in vivo assays gave a wealth of information, including steady-state concentrations, translocation factors, elimination rate constants, and half-life of PFASs. The in vivo tracing method for live plants can provide much needed and unique information to evaluate the risk of PFASs, which are very important for the safety of agriculture production.

Magnetic molecular imprinted covalent organic framework composite for the magnetic solid-phase extraction of bisphenol AF

A magnetic molecular imprinted covalent organic framework composite (MCOF-MIP) that possessed the 'dual-selectivity' of a covalent organic framework and molecular imprinted polymer (MIP) with rapid response performance was successfully prepared for the removal of bisphenol AF (BPAF) from real water and blood samples. First, the MCOF was separately synthesized using magnetic Fe3O4 as the magnetic core, 1,3,5-triaminobenzene and 2,5-dibromobenzene-1,4-diformaldehyde as precursors and a deep eutectic solvent (DES) as the solvent using a solvothermal synthesis method. The MCOF showed high crystallinity and good adsorption capacities for BPAF (107.4 mg g-1), bisphenol A (113.6 mg g-1), bisphenol S (120.0 mg g-1) and bisphenol F (82.1 mg g-1). To further improve the selectivity for BPAF, an MIP, which uses BPAF as a template, was introduced to form the MCOF-MIP. Due to the dual selectivity of MCOF and MIP, the MCOF-MIP exhibited relatively high selective adsorption capacity to BPAF (243.1 mg g-1) compared to that for the MCOF (107.4 mg g-1), while the adsorption capacities (149.7-109.4 mg g-1) for the other three compounds were not significantly improved. Furthermore, a magnetic solid-phase extraction (MSPE) method was established, and MSPE parameters such as adsorbent dosage, adsorption time, desorption solvent and desorption time were optimized. Combined with high-performance liquid chromatography with diode-array detection (HPLC-DAD) analysis, a rapid and sensitive method was developed to detect BPAF, which showed good linearity (r > 0.9969) ranging from 0.1 to 400 μg mL-1. Low limits of detection (0.04 μg mL-1, S/N = 3) and quantitation (0.1 μg mL-1, S/N = 10) and good precision with low relative SDs (<1.2 % for intra-day and <1.1 % for inter-day) were also obtained. Finally, MSPE coupled with HPLC-DAD was employed for the analysis of BPAF in water and blood samples, and the recoveries of BPAF were satisfactory (91.1-112.6 %).

Virgin Camellia Seed Oil Improves Glycolipid Metabolism in the Kidney of High Fat-Fed Rats through AMPK-SREBP Pathway

Camellia seed oil (CO) is used as edible oil in southern China because of its excellent fatty acid composition and abundant bioactive compounds. Chronic kidney disease (CKD) is one of the most common chronic degenerative diseases in China, and active compounds in vegetable oil, like virgin olive oil, have been demonstrated to be efficacious in the management of CKD. In this study, virgin CO was refined using a standard process. The refining had minimal impact on the fatty acid composition, but significantly reduced the presence of bioactive compounds like polyphenols in CO. Sprague-Dawley (SD) rats fed with high fat diet (Group G) were treated with either virgin (Group Z) or refined CO (Group R). The oral administration of CO alleviated lipid accumulation and decreased body and kidney weight gain. Furthermore, treatment with virgin CO increased the renal ATP content. The renal expression levels of AMPK and key enzymes involved in fatty acid oxidation (CPT-1 and ACOX1) and glycolysis (HK, PFK, PK and GAPDH) were up-regulated in Group Z, thereby enhancing the ATP production. Virgin CO treatment downregulated the expression level of SREBP2 and its downstream target genes, such as ACC, FAS, and HMGCR, which reduced lipid synthesis. These findings indicate that virgin CO improves glycolipid metabolism and restores energy homeostasis in the kidneys of rats fed with a high-fat diet by modulating the AMPK-SREBP-signaling pathway, suggesting the potential of active compounds in virgin CO for managing the renal failure associated with glycolipid dysmetabolism.

Green and Facile Preparation of Covalent Organic Frameworks Based on Reaction Medium for Advanced Applications

Covalent organic frameworks (COFs), as a new class of crystalline, well-ordered, and porous materials with intermittent constructions, are formed via organic structural parts connected through covalent bonds. These materials have been employed in several fields comprising pollutant adsorption and separation, catalysis, electrical conductivity, gas storage, etc. The preparation of COFs is mainly applied in tubes with high temperatures and degassing treatment. Furthermore, the reaction medium is involved in toxic organic solvents like toluene, dioxane, mesitylene, acetonitrile, and so on. Hence, discovering clean medium and green approaches has attracted wide attention. Recently, facile, less dangerous, and greener methods have been developed for COFs synthesis in diverse applications like performing the reaction at ambient temperature or employing aqueous solvents, ionic liquids, and a mixture of organic solvents/water. This review article summarizes the eco-friendly production approaches of COFs for diverse applications.

Molecularly imprinted polymers based on calcined rape pollen and deep eutectic solvents for efficient sinapic acid extraction from rapeseed meal extract

Substances that possess hierarchical and interconnected porous features are ideal choices for acting as skeletons to synthesize surface molecularly imprinted polymers (MIPs). In this work, rape pollen, a waste of biological resources, was calcined and a porous mesh material with a high specific surface area was obtained. The cellular material was adopted as a supporting skeleton to synthesize high-performance MIPs (CRPD-MIPs). The CRPD-MIPs presented an ultrathin imprinted layered structure, with an enhanced adsorption capacity for sinapic acid (154 mg g^-1) relative to the non-imprinted polymers. The CRPD-MIPs also exhibited good selectivity (IF = 3.24) and a fast kinetic adsorption equilibrium (60 min). This method exhibited a good linear relationship (R2 = 0.9918) from 0.9440 to 29.26 μg mL^-1, and the relative recoveries were 87.1-92.3%. The proposed CRPD-MIPs based on hierarchical and interconnected porous calcined rape pollen may be a valid program for the selective extraction of a particular ingredient from complicated actual samples.

A sensitive fluorescent assay based on gold-nanoclusters coated on molecularly imprinted covalent organic frameworks and its application in malachite green detection

Malachite green (MG), as a parasiticide, is widely used in aquaculture to increase the production of the fishery industry. It poses a great danger to both the food system and the human body. In this study, a one-pot reverse microemulsion polymerization was employed to combine the gold nanoclusters (AuNCs) with molecularly imprinted polymers (MIPs) and covalent organic frameworks (COFs) to synthesize an efficient fluorescent hybrid probe (AuNCs@COFs@MIPs) for selective detection of MG. The specific recognition of AuNCs@COFs@MIPs towards MG triggers the fluorescence quenching of AuNCs. The fluorescent response was linearly related to the concentration over the range of 10-150 nmol/L with a limit of detection of 2.78 nmol/L. In addition, the proposed probe was further applied to fish and water samples. A favorable recovery ranged from 97.34 to 101.51 % toward trace amounts of MG indicating its promising application for detecting residue of veterinary drugs.

Carbon nanomaterial-based molecularly imprinted polymer sensors for detection of hazardous substances in food: recent progress and future trends

The presence of various harmful substances in food is significantly risky to human health. Therefore, simple, rapid, and selective food hazard analysis tools have become a focus of sensing research. At present, molecularly imprinted polymers (MIPs) have attracted more and more attention because of their easy preparation and high selectivity. Due to their simple preparation, low cost, large specific surface area, and high conductivity, carbon nanomaterial can be used as sensing substrate carriers. Therefore, the combination of carbon nanomaterial with MIPs has attracted great attention. This paper summarizes the development, composition, and preparation methods of MIPs, as well as the latest research progress in carbon nanomaterials for the detection of various food hazards using sensors. In addition, the practical applications of carbon nanomaterial-based MIP sensors, their current challenges and future trends, and the ongoing efforts devoted to developing new and efficient carbon nanomaterial-based MIP sensing platforms are also introduced.

β-Cyclodextrin-Based Supramolecular Imprinted Fiber Array for Highly Selective Detection of Parabens

A novel high-throughput array analytical platform based on derived β-cyclodextrin supramolecular imprinted polymer (SMIP) fibers was constructed to achieve selective enrichment and removal of parabens. SMIP fiber arrays have abundant imprinting sites and introduce the host−guest inclusion effect of the derived β-cyclodextrin, which is beneficial to significantly improve the adsorption ability of fiber for parabens. Upon combination with HPLC, a specific and sensitive recognition method was developed with a low limit of detection (0.003−0.02 µg/L, S/N = 3) for parabens analysis in environmental water. This method has a good linearity (R > 0.9994) in the linear range of 0.01−200 µg/L. The proposed SMIP fiber array with high-throughput adsorption capacity has great potential in monitoring water pollution, which also provides a reliable reference for the analysis of more categories of pharmaceutical and personal care product pollutants.

Portable and on-site electrochemical sensor based on surface molecularly imprinted magnetic covalent organic framework for the rapid detection of tetracycline in food

In this study, for the first time, surface molecularly imprinted magnetic covalent organic frameworks (Fe₃O₄@COFs@MIPs) were combined with disposable screen-printed electrode (SPE) to construct a portable and on-site electrochemical sensor for the rapid detection of tetracycline (TC). The Fe₃O₄@COFs@MIPs, which was prepared by layer-by-layer modification method, had good magnetism and excellent adsorption ability. With the help of disposable SPE, equipped with a magnet, the electrode modification process was simplified and the detection efficiency was improved. Under optimal conditions, the fabricated electrochemical sensor exhibited linearity ranging from 1 × 10^-10 to 1 × 10^-4 g mL^-1. It had good selectivity, excellent reproducibility, desirable stability and remarkable applicability. The fabricated sensor was successfully applied to detect TC in real samples with satisfactory recoveries (96.15-106.20%). The detection strategy separated the recognition and adsorption process from the electrochemical detection process, providing a design idea for the application of COFs in the construction of high-efficiency molecularly imprinted electrochemical sensors.

Three-Dimensional Ordered Macroporous Magnetic Inverse Photonic Crystal Microsphere-Based Molecularly Imprinted Polymer for Selective Capture of Aflatoxin B1

Development of an efficient detection method to monitor residual mycotoxins in food is very important to ensure food safety, but the complex food matrix seriously affects the detection sensitivity and accuracy. Here, using a three-dimensional ordered macroporous magnetic inverse photonic crystal microsphere (MPCM) as the supporting material, a molecularly imprinted polymer (MIP) that can selectively recognize aflatoxin B₁ (AFB₁) was synthesized through the dummy template imprinting strategy. The MPCM@MIP prepared by employing 5,7-dimethoxycoumarin as the template and methacrylic acid as the functional monomer displayed selectivity toward AFB₁ (imprinting factor of 1.5) and could be used as a solid-phase extraction material. By coupling with high-performance liquid chromatography, an analytical method targeting AFB₁ was established and displayed a wide linear range of 5-1000 ng/mL with a low detection limit of 0.4 ng/mL. The method showed a good recovery rate of 73-92% in AFB₁-spiked soy sauce and vinegar samples. Moreover, the MPCM@MIP could be separated from the sample solution easily because of its magnetic performance, displaying a promising future not only in the enrichment of AFB₁ to improve the detection sensitivity and accuracy but also in the removal of AFB₁ from food and environmental samples.

Functional Nanoparticles with Magnetic 3D Covalent Organic Framework for the Specific Recognition and Separation of Bovine Serum Albumin

Glutathione functionalized magnetic 3D covalent organic frameworks combined with molecularly imprinted polymer (magnetic 3D COF–GSH MIPs) were developed for the selective recognition and separation of bovine serum albumin (BSA). Ultrasonication was used to prepare magnetic 3D COFs with high porosity (~1 nm) and a large surface area (373 m² g⁻¹). The magnetic 3D COF–GSH MIP nanoparticles had an imprinting factor of 4.79, absorption capacity of 429 mg g⁻¹, magnetic susceptibility of 32 emu g⁻¹, and five adsorption–desorption cycles of stability. The proposed method has the advantages of a shorter equilibrium absorption time (1.5 h), higher magnetic susceptibility (32 emu g⁻¹), and larger imprinting factor (4.79) compared with those reported from other studies. The magnetic 3D COF–GSH MIPs used with BSA had selectivity factors of 3.68, 2.76, and 3.30 for lysozyme, ovalbumin, and cytochrome C, respectively. The successful recognition and separation of BSA in a real sample analysis verified the capability of the magnetic 3D COF–GSH MIP nanoparticles.

Photonic and Magnetic Dual-Responsive Molecularly Imprinted Sensor for Highly Specific Recognition of Enterovirus 71

The specific identification and detection of a virus are the critical factors to identify and control an epidemic situation. In this study, a novel photonic-magnetic responsive virus-molecularly imprinted photochemical sensor was constructed for recognition of enterovirus 71. As designed, the double-bond-modified magnetic metal organic framework and 4-(4'-acryloyloxyazo) benzoic acid were used as a magnetic carrier and light-responsive functional monomer, respectively. The structure of the recognition site of the virus-molecularly imprinted nanospheres can be photo-switched between two different structures to achieve rapid release and specific binding to the target virus. Additionally, the introduction of a magnetic core enables a rapid separation and recycling of imprinted particles. The device achieves a performance with high-specificity recognition (imprinting factor = 5.1) and an ultrahigh sensitivity with a detection limit of 9.5 × 10^-3 U/mL (3.9 fM). Moreover, it has good reproducibility and can be stored for as long as 6 months. Thus, the approach used in this work opens a new avenue for the construction of multiresponsive virus sensors.

Smart Nanoparticles for Chemo-Based Combinational Therapy

Cancer is a heterogeneous and complex disease. Traditional cancer therapy is associated with low therapeutic index, acquired resistance, and various adverse effects. With the increasing understanding of cancer biology and technology advancements, more strategies have been exploited to optimize the therapeutic outcomes. The rapid development and application of nanomedicine have motivated this progress. Combinational regimen, for instance, has become an indispensable approach for effective cancer treatment, including the combination of chemotherapeutic agents, chemo-energy, chemo-gene, chemo-small molecules, and chemo-immunology. Additionally, smart nanoplatforms that respond to external stimuli (such as light, temperature, ultrasound, and magnetic field), and/or to internal stimuli (such as changes in pH, enzymes, hypoxia, and redox) have been extensively investigated to improve precision therapy. Smart nanoplatforms for combinational therapy have demonstrated the potential to be the next generation cancer treatment regimen. This review aims to highlight the recent advances in smart combinational therapy.

Highly selective magnetic dual template molecularly imprinted polymer for simultaneous enrichment of sulfadiazine and sulfathiazole from milk samples based on syringe-to-syringe magnetic solid-phase microextraction

Antibiotics, such as sulfadiazine and sulfathiazole, are widely used in veterinary applications which can result in remains in edible animal products. Therefore, there is an immense need for a reliable, selective, sensitive, and simple analytical technique for monitoring the concentration of sulfadiazine (SDZ) and sulfathiazole (STZ) in edible animal products. In this regard, we developed a magnetic dual template molecularly imprinted polymer (MMIP) to determine the SDZ and STZ in milk samples. For the sensitive and selective extraction and determination of target analytes, MMIPs have been combined with the syringe-to-syringe magnetic solid-phase microextraction (SS-MSPME) method. In addition, we used central composite design (CCD) for the extraction of SDZ and STZ. With optimum conditions, an efficient, rapid, and convenient technique for the preconcentration and determination of SDZ and STZ in milk samples by SS-MSPME coupling with HPLC-UV was developed. Using our combined approach, the limits of detection are 0.9 and 1.3 ng mL^-1 for SDZ and STZ, respectively, along with good linearity and determination coefficients higher than 0.98. Our method demonstrates a practical approach for the deduction of antibiotics in milk samples with high recoveries and selectivity.

Metal-coded hydrogel magnetic molecularly imprinted polymer for preconcentration and cleanup of sarcosine: Determination in urine; coupled to on-column capillary electrophoresis

In this study, sarcosine metal-coded hydrogel magnetic molecularly imprinted polymer (Hydro-MeC-MMIP) has been fabricated and coupled to on-column derivatization capillary electrophoresis (CE). As a metal-coding approach, sarcosine-Cu²⁺-ligand (Sar-Cu²⁺-L) chelate complex was introduced as a template to overcome the problems associated with the fabrication of MMIP for a small molecule having limited functional groups such as sarcosine. To our best knowledge, it is the first time that methacrylamide (MA) coated Fe₃O₄ (Fe₃O₄@MA) with abounded reactive double-bound on the surface has been used as a magnetic core in the one-pot synthesis of MMIPs. As prepared, Hydro-MeC-MMIP was characterized by different microscopic, spectroscopic, and thermal gravimetric methods. Hydro-MeC-MMIP was used to extract and preconcentrate sarcosine in the urine sample with no treatment and dilution. Sarcosine was quantified by on-column derivatization capillary electrophoresis equipped with a photodiode array detector. A mixture of thirteen amino acids was separated with a total run time of 12 min. Three structural analogs, including alanine, sarcosine, and glycine, were significantly resolved. Under optimal experimental conditions, the method's detection and quantification limits were 9.93 and 33.10 ng mL^-1, respectively. The linear range of 50-2000 ng mL^-1 and 96% recovery, along with the relative standard deviation of 6.07% (n = 6) for the target amino acid, were obtained. This method provides a simple, low-cost, fast, and efficient tool for extracting and quantifying sarcosine in the urine. The present method can address inconsistency in evaluating sarcosine as a candidate biomarker for prostate cancer with a simple CE/UV; no need for a sophisticated detection system such as a mass spectrometer.