Development of hydroxypropyl cellulose and graphene oxide modified molecularly imprinted polymers for separation and enrichment of podophyllotoxin.

A novel hydroxylpropyl cellulose (HPC) modified graphene oxide (GO)-based molecularly imprinted polymers (HPC-GO-MIP) have been developed as a solid phase extraction (SPE) material for the selective separation and extraction of podophyllotoxin. In this strategy, the cellulose with rich hydroxyl groups was introduced to form bi-functional monomers with methacrylic acid to provide more recognition sites for the improving of extraction efficiency, then GO was added as a two-dimensional substrate for MIP to improve the material morphology and surface area. The extraction performances of obtained HPC-GO-MIP material were tested, and the results prove its high efficiency and selectivity for podophyllotoxin extraction. The saturated adsorption capacity reached 23.1 µg/mg, and high enrichment efiiciency of 463.8 folds was realized under the premise of ensuring the recovery rate. The selective imprinting factor was much higher than those of kaempferol and quercetin, which were the main compounds in podophyllum fruit. Under the optimized SPE conditions, the HPC-GO-MIP based SPE-HPLC method showed the detection limit of 14.2 ng/mL for podophyllotoxin assay. When applied to podophyllum fruit samples, the material showed excellent ability of selective separation and enrichment of podophyllotoxin, and the relative standard deviations (RSD) of intra and inter batches were less than 8.1 % and 5.7 % in real samples detection. The HPC-GO-MIP SPE method broadened the application for high multiple extraction in trace analyte samples and provided a valuable solution to improve the selective separation and detection.

A quantum dot aptamer fluorescent sensor based on magnetic graphene oxide for the detection of zearalenone.

As an estrogenic mycotoxin found in a wide range of agricultural crops, the toxicity of zearalenone (ZEN) poses a serious risk to human health. Accordingly, to achieve rapid detection of zearalenone in complex samples, an aptamer fluorescence sensor based on magnetic graphene oxide was developed. Compared with traditional methods, this technique has the virtues of simple operation, low cost, and reliable performance. Magnetic graphene oxide (MGO) was synthesized as a fluorescent bursting agent, using a chemical precipitation approach by depositing Fe3O4 on the surface of graphene oxide. As a fluorescent probe, an aptamer coupling with CdTe quantum dots and zearalenone was used. Following the specific binding of zearalenone and the aptamer, the affinity interaction between the fluorescent probe and MGO was weakened, resulting in the recovery of fluorescence and making the qualitative and quantitative analysis of zearalenone available via fluorescence intensity determination. The results indicated that the method's linear range was 5-120 µg L-1 and its detection limit was 2.9 µg L-1. In addition, the recoveries varied from 76.4 to 118.8% for crop samples, with relative standard deviations (RSDs) between 0.8 and 9.5%, which suggests an effective method for the separation and detection of mycotoxins in actual environmental samples.

Gigantic and Continuous Output Power in Ionic Thermo-Electrochemical Cells by Using Electrodes with Redox Couples.

The main obstacle of ionic thermo-electrochemical cells (TECs) in continuous power supply lies in a low heat-to-electricity energy conversion efficiency because most TECs work in thermodiffusion mode in which the ions are confined in a liquid/electrolyte media. The introduction of the redox couple onto the electrode surface may overcome the obstacle by resolving the low mass transport rate of ions caused by the redox process occurring near but not on the electrode surface. Herein, the authors demonstrate enhancement of TECs by integrating the redox couple directly onto the electrode surface to maximize the mass transport efficiency. A discontinuous interfacial modification strategy is developed by using a carbon cloth/iron (II/III) phytate as the symmetric electrodes. The gelled electrolyte consisting of a polyacrylamide matrix and phytic acid is shown to promote selective ion diffusion. A synergistic combination consisting of the thermodiffusion effect and redox reactions on the electrode is established in a pre-treated layout. Such TEC affords a high output voltage of 0.4 V, an excellent instantaneous output power density (20.26 mW m-2 K-2 ) and a record-high 2 h output energy density (2451 J m-2 ) under TH = 30 °C with TC = 15 °C, with an ultrahigh Carnot-relative efficiency of 1.12%.

New azaphilones from mangrove endophytic fungus Penicillium sclerotiorin SCNU-F0040.

Two new sclerotioramines (1 and 2) and a new natural product of sclerotioramine analog (3), together with seven known compounds have been isolated from the mangrove endophytic fungus Penicillium sclerotiorin SCNU-F0040. Their structures were identified based on the 1 D, 2 D NMR and HRESIM spectra. The absolute configurations of new compounds were deduced by specific rotation data and electronic circular dichroism spectra. All the isolated new compounds were tested on anti-diabetes activity by using a-glucosidase inhibition assay and anti-inflammatory activity by using cyclooxygenase inhibition assay, respectively. Compounds 1 and 2 have a-glucosidase inhibition activity with IC50 values of 102.3 and 217.5 µM. Compound 2 shows a moderate cyclooxygenase-2 inhibitory activity with an IC50 value of 47.8 µM.

Fabrication of magnetic molecularly imprinted polymers based on aptamers and ß-cyclodextrin for synergistic recognition and separation of tetracycline.

Tetracycline is extensively used as an antibiotic in animal husbandry, and there arose an increase in antibiotic resistance genes in the environment, posing a threat to human health. Motivated by this, a magnetic molecularly imprinted material based on synergistic recognition (1 + 1>2) was constructed and coupled with high-performance liquid chromatography to detect ultra-trace tetracycline in complicated samples. In this case, the molecularly imprinted polymers were synthesized via a "one-pot" method and acted as recognition elements on the surface of silica-coated ferroferric oxide particles. Aptamers and ß-cyclodextrin, as functional monomers, had a synergistic effect on the recognition of tetracycline and the synergistic recognition factor was 1.7. Meanwhile, the material exhibited high selectivity to tetracycline with an imprinting factor of 7.6. In addition, compared to being modified on the surface, the stability of the aptamers was effectively improved by cross-linking in the molecularly imprinted polymer framework. Relevant experimental conditions, such as buffers, concentration of magnesium ions and adsorption time, were optimized. As a result, the method showed a limit of detection of 1.0 µg L-1 and the linearity range of 0.005-0.5 mg L-1, as well as certain reproducibility and stability. Furthermore, when applied for the analysis of animal feed samples, a significant reduction of matrix interference was observed with satisfactory recoveries (85.0-111.5%), which emphasized the good accuracy and practicability of the established method. For these advantages, the proposed method represents a versatile and powerful tool for the separation and detection of small molecule compounds in complicated real samples.