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.

Colorimetric and ratiometric supramolecular AIE fluorescent probe for the on-site monitoring of fipronil.

The overuse of fipronil (FPN, a broad-spectrum insecticide) in agriculture has brought great concerns for environmental pollution and food safety. The development of a rapid, reliable, and portable analytical method for the on-site monitoring of FPN is therefore of great significance but is full of challenge. Herein, a novel supramolecular probe using human serum albumin (HSA) as the host and an aggregation-induced emission-active fluorescence probe LIQ-TPA-TZ as the guest was developed for the colorimetric and ratiometric detection of FPN, displaying fast response (30 s), high sensitivity (LOD ∼ 0.05 µM), and good selectivity and anti-interference performance. Moreover, portable paper-based test strips could be facilely obtained and utilized for the determination of FPN, showing colorimetric changes from yellow to orange. This supramolecular probe also demonstrated great potential in real applications for choosing the best cleaning method to reduce the residue rate of FPN on apples. This study provides a versatile tool for the fast and real-time analysis of FPN, which greatly benefits the on-site determination of pesticides with the use of simple testing apparatus.

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.

Bilberry Anthocyanins (Vaccinium myrtillus L.) Induced Apoptosis of B16-F10 Cells and Diminished the Effect of Dacarbazine.

Anthocyanins have been reported to have potential as dietary or pharmaceutical supplements in the application of cancer prevention and adjunctive treatment. However, there are few studies on the effect of anthocyanins on melanoma, which have only been performed in cell lines. The objective of this work was to investigate the anticancer effects and mechanisms of bilberry anthocyanin extract (BAE) on melanoma In Vitro and In Vivo. Moreover, a primary study was done to investigate how BAE influenced C57BL/6 mice bearing subcutaneous B16-F10 tumors treated with dacarbazine (DTIC). BAE-induced apoptosis in B16-F10 cells was associated with activation of the mitochondrial pathway induced by increased reactive oxygen species. More, In Vivo anticancer activity studies indicated that BAE attenuated melanoma growth, as identified by hematoxylin-eosin staining, Ki-67, and TUNEL assays. Further western blot results revealed higher phospho-Akt expression with the combination of BAE and DTIC, indicating no suppression of the PI3K/AKT signaling pathway. In summary, this study demonstrated the anti-melanoma activity of BAE and investigated its mechanism. Notably, it should be careful to use products enriching BAE for those melanoma patients treated with DTIC.

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.

Designing and preparing metal mediated magnetic imprinted polymer for recognition of tetracycline.

Recently, metal mediated molecularly imprinted polymers (MMIPs) raise extensive attention due to their special adsorption/desorption mechanism. And the metal ion plays a key role both for MMIPs preparation and molecular recognition. But it is still a big question to select one suitable metal ion. To overcome above problem, one computational approach was proposed by calculating interaction energy (ΔE) of ternary complexes (monomer-M2+-template) with GAMESS software at the PBE0 level. Finally Cu(II) was screened from four doubly charged metal ions with different radii. Then Cu mediated MIP was prepared via surface imprinting technique with Fe3O4 as the core in a water system. Subsequently, the adsorption behavior of the MMIP immobilized Cu(II) was investigated in detail. The results indicated the microspheres own excellent specificity and selectivity towards tetracycline (TC), as well as long-term stability and good reproducibility. The apparent maximum binding capacity and the imprinting factor were as high as 163.5 mg g- 1 and 19, respectively. Coupled with HPLC-PDA, the microspheres was successfully used as a dispersed solid phase extraction material to extract trace TC in chicken liver. At three spiking levels, mean recoveries ranged from 89.3% to 97.1% with relative standard deviations less than 4.0% (n = 3). Limits of detection and quantitation were 0.0073 mg kg- 1 and 0.024 mg kg- 1, respectively, which can meet the strict requirement of the regulations stipulated by EU. Moreover, preliminary studies showed the radius of the metal ion and ΔE of the complexes all affect the adsorption capacity, specificity and mass transfer rate of the MMIP.

Copper mediated molecularly imprinted polymers for fast recognizing tylosin.

As one kind of artificial antibody, molecularly imprinted polymers (MIPs) has been widely used to separate/enrich target molecules from samples with the complex matrix prior to instrumental analysis. In this work, one novel copper mediated magnetic MIPs was developed towards anti-bacteria macrolide antibiotic tylosin (TYL). The obtained microspheres had a lot of convexities distributed evenly on the surface. And it exhibited high hydrophilicity and superparamagnetic ability, as well as excellent selectivity and specificity. Notably, it only took 5 min to reach the absorption equilibrium for TYL, which made it highly feasible for high-throughput analysis. Furthermore, the microspheres was applied as the magnetic dispersed solid phase extraction material to enrich trace TYL residue in (spiked) human urine. At three spiking levels, mean recoveries are in the range of 76.42-93.72% with relative standard deviations of 2.75-8.24% (n = 3) with HPLC/UV-Vis. The work provided one promising reference to prepare novel solid phase extraction materials for enriching/separating trace component in complex matrix.

[Preparation of molecularly imprinted polymers based on covalent organic frameworks and their application to selective recognition of trace norfloxacin in milk].

Norfloxacin (NFX) is an antibiotic that is widely used in animal husbandry. However, the presence of NFX even in trace amounts in animal-derived food may harm human health. Therefore, it is of practical significance to establish a method for monitoring NFX residues in food. Molecularly imprinted polymers (MIPs) imitate interactions established by natural receptors to selectively retain a target molecule, like antibodies or antigens do. MIPs have been widely employed in the selective recognition of specific target molecules from complex samples. Covalent organic frameworks (COFs) are a new type of organic polymer with uniform and ordered crystal structures. COFs form crystal structures by constructing organic units for ordered assembly through reversible chemical reactions. Their porous structure, regular morphology, and easy modification make COFs promising for use as excellent adsorbent carriers. Owing to these advantages of COFs, researchers have attempted to coat one MIP layer on COFs; however, the preparation methods are time-consuming and laborious, and the conditions are harsh. Hence, this study proposes a simple and rapid method for the preparation of novel MIPs with COFs as the support (DP-COF@MIPs) for the selective recognition of NFX. First, a Schiff-base COF (DP-COF) was rapidly synthesized using 3,3'-diaminobenzidine and p-phthalaldehyde with a metal trifluorate as a catalyst at room temperature. Subsequently, a two-step sequence was adopted as the synthesis strategy using NFX as the template, methacrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a crosslinking agent. The entire synthesis was completed within 5 h under mild conditions. The material was then characterized by multiple analytical methods, including field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and the Brunauer-Emmett-Teller (BET) method (to determine the specific surface area). The experimental results confirmed the successful preparation of DP-COF@MIPs. The DP-COF@MIPs presented a rough and porous surface, with a pore size of approximately 17.79 nm (mesoporous structure). The properties of the material were evaluated by adsorption and regeneration experiments. The kinetic adsorption experiment showed that the DP-COF@MIPs reached adsorption equilibrium in 90 min. Two straight lines were fitted using the pseudo-second-order kinetics model based on the experimental results for thermodynamic adsorption, indicating that the adsorption process was primarily dominated by chemical adsorption. The maximum apparent adsorption capacity was 41.57 mg/g. In the selective and competitive binding test, five drugs, namely ciprofloxacin, dimetridazole, oxytetracycline, sulfadiazine, and chloramphenicol, were selected as the interferents. The experimental results showed that the DP-COF@MIPs possessed good stereoselectivity and competitive recognition ability. The regeneration of DP-COF@MIPs was evaluated by multiple cycles of adsorption-desorption experiments. The loss in the adsorption capacity of the particles was only approximately 4.7% after seven adsorption-desorption cycles. These results from the regeneration experiments show that the DP-COF@MIPs had high stability and reusability in the selective adsorption and separation of NFX. In addition, the employed method could accurately identify trace NFX in milk samples. The average recoveries were in the range of 88.8%-92.9% at three spiked levels (0.03, 0.10, and 0.30 mg/L) with relative standard deviations (RSDs) in the range of 0.6-1.7% (n=3). Notably, the method could successfully determine NFX at contents as low as 0.0020 mg/L in the milk sample with an average recovery of 77.6% and RSD of 6.4% (n=3). This concentration is one-fiftieth of the maximum residue level stipulated by the European Union (EU), and even lower than the limit of detection (LOD) of conventional high performance liquid chromatography (HPLC) methods. The above results confirm that DP-COF@MIPs can be used to determine trace NFX in actual complex samples using HPLC equipment, even when coupled to conventional UV-Vis detectors. This study offers a facile and general method for the preparation of MIPs based on COFs with selective recognition ability.

Three New C19-Diterpenoid Alkaloids from Aconitum novoluridum.

Three new aconitine-type C19-diterpenoid alkaloid namely novolunines A (1), B (2), and C (3), along with fifteen known diterpenoid alkaloids were isolated from the roots of Aconitum novoluridum, whose phytochemical investigations have never been reported before. The structures of three new alkaloids were established on the basis of spectra data (high-resolution electrospray ionization (HR-ESI)-MS, IR, one dimensional (1D)- and 2D-NMR). Noteworthily, novolunines A (1) and B (2) are two diterpenoid alkaloids bearing conformational isomerism. In addition, the diterpenoid alkaloids 1-3 did not show any anti-acetylcholinesterase (AChE) or anti-inflammatory activities.

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

Molecularly imprinted polymers (MIPs) are a kind of synthetic receptor-like materials. They have drawn more and more attention in the past decades. In this work, a facile method was developed to prepare porous magnetic MIPs utilizing metal coordination. The preparation is simply done using conventional oil-in-water emulsifier-free emulsion technology by mixing poly(styrene-co-itaconic acid), oxytetracyclin (OTC), Cu(II), and Fe3O4 magnetic fluid in one pot with a reaction time of 3 h. The product shows high specificity and selectivity toward OTC, as well as an excellent saturation adsorption capacity (62.567 mg/g). Emphasizing that the imprinting factor is 29, which is the highest one among the reported MIPs to the best of our knowledge. Combined with high-performance liquid chromatography, it was used successfully to determine OTC in pork liver, one of the most complex bio-samples. Recoveries are higher than 91.0% with relative standard deviations less than 4.5% at three spiked levels (n = 3). All evidence testifies that the MIPs based on metal coordination show excellent recognition selectivity and specificity, as well as large rebinding capacity. The strategy holds promise as a reliable, extensible, and versatile way for preparing a metal ion-mediated molecular-imprinting polymer.

Preparation of porous magnetic molecularly imprinted polymers for fast and specifically extracting trace norfloxacin residue in pork liver.

Here, magnetic molecularly imprinted polymers were designed for norfloxacin via oil-in-water emulsifier-free emulsion method. It was prepared by simply mixing norfloxacin, methacrylic acid-co-ethylene glycol dimethacrylate copolymer, and Fe3 O4 together at room temperature. Characterized by multiple analytical tools, the particle size, pore size, pore volume, specific surface area, and saturation magnetization of the product were about 30 µm, 10-500 nm, 2.92 mL/g, 105.84 m2 /g, and 3.052 emu/g, respectively. And the adsorption capacity was high at 27.04 mg/g towards norfloxacin. Combined with ultra high performance liquid chromatography, it was used to determine norfloxacin in real samples. Average recoveries were above 77.44% with relative standard deviations between 1.21 and 6.85% at three spiked levels (n = 3) for lake water and pork liver. The determination was achieved for the most complex biosample pork liver spiked with norfloxacin low to 30 ng/g, about 100 times less than the maximum residue limit regulated by Commission of the European Communities. All evidences demonstrated that the magnetic molecularly imprinted polymers can be used in practice for monitoring norfloxacin either in environmental water or meat product with high accuracy and reliability.