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The extraction of total flavonoids from Hylotelephium spectabile (Boreau) H. Ohba (H. spectabile) leaves was studied through the use of a double enzyme-assisted ultrasonic method, and the extraction process was optimized using the Box-Behnken design. Eight different macroporous resins were screened for purification in single-factorial experiments, and the flavonoid compounds in the extract of H. spectabile leaves were identified using HPLC-MS. Through the evaluation of the total reducing capacity and capacity for reducing 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH), hydroxyl radicals (·OH), and 2,2'-biazobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), the in vitro antioxidant activities of the crude extracts of the total flavonoids and purified total flavonoids of H. spectabile leaves were investigated. The results showed that the most efficient conditions for flavonoid extraction were an ultrasonic extraction time of 60 min, an ethanol concentration of 35%, a liquid-to-material ratio of 20:1 mL/g, and an amount of enzyme (cellulose/pectinase = 1:1) of 1.5%, forming H. spectabile powder. Under these conditions, the total flavonoid extraction rate in the H. spectabile leaf extract was 4.22%. AB-8 resin showed superior performance in terms of purification, and the optimal adsorption and desorption times were 1.5 h and 3 h, respectively. The recommended parameters for purification included a liquid volume of 5.5 BV, a flow rate of 1.2 BV/min, a pH of 5, and a concentration of 0.8 mg/mL. The observed order for reducing capacity was ascorbic acid (VC) > rutin > purified total flavonoids > crude extract of total flavonoids. The purified total flavonoid extract from H. spectabile showed a good scavenging ability against DPPH, ·OH, and ABTS·+, suggesting strong antioxidant activity. Therefore, this study can serve as technical support and reference data for the further development and utilization of H. spectabile resources.
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Introduction: During electroencephalography (EEG)-based motor imagery-brain-computer interfaces (MI-BCIs) task, a large number of electrodes are commonly used, and consume much computational resources. Therefore, channel selection is crucial while ensuring classification accuracy. Methods: This paper proposes a channel selection method by integrating the efficient channel attention (ECA) module with a convolutional neural network (CNN). During model training process, the ECA module automatically assigns the channel weights by evaluating the relative importance for BCI classification accuracy of every channel. Then a ranking of EEG channel importance can be established so as to select an appropriate number of channels to form a channel subset from the ranking. In this paper, the ECA module is embedded into a commonly used network for MI, and comparative experiments are conducted on the BCI Competition IV dataset 2a. Results and discussion: The proposed method achieved an average accuracy of 75.76% with all 22 channels and 69.52% with eight channels in a four-class classification task, outperforming other state-of-the-art EEG channel selection methods. The result demonstrates that the proposed method provides an effective channel selection approach for EEG-based MI-BCI.
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An environmental strategy for developing sustainable materials presents an attractive prospect for wastewater remediation. Herein, a facile, green, and economical strategy is proposed to fabricate magnetic composite nanoparticles (NPs) toward cationic dye adsorption and selective degradation. To prepare the composite TiO2-PEI-TA@Fe3O4 NPs, tannic acid (TA) and polyethyleneimine (PEI) were first used to decorate Fe3O4 NPs at aqueous solution, and then TiO2 NPs were anchored onto the surfaces of Fe3O4 NPs based on the catecholamine chemistry. The chemical composition and microstructure of the obtained NPs were systematically characterized. The NPs not only exhibited adsorption ability for the cationic dye of methylene blue (MB) but also responded to ultraviolet light to selectively degrade the adsorbed MB, and the removal (adsorption and/or degradation) ratio for MB could reach 95%. In addition, cyclic experiments showed that the removal ratio of the composite NPs for MB could still be maintained more than 85% even after five cycles. Given by the above-mentioned advantages, such a green and facile strategy for combining the adsorption and degradation methods to construct magnetic nanocomposites exhibits potential applications in cationic dye selective removal and sustainable wastewater remediation.
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Heparin is the highest negatively charged biomolecule, which is a polysaccharide belonging to the glycosaminoglycan family, and its role as a regulator of various proteins, cells and tissues in the human body makes it an indispensable macromolecule. Heparin-based hydrogels are widely investigated in various applications including implantation, tissue engineering, biosensors, and drug-controlled release due to the 3D-constructs of hydrogels. However, heparin has supply and safety problems because it is usually derived from animal sources, and has the clinical limitations of bleeding and thrombocytopenia. Therefore, analogous heparin-mimicking polymers and hydrogels derived from non-animal and/or totally synthetic sources have been widely studied in recent years. In this review, the progress and potential biomedical applications of heparin-based and heparin-inspired hydrogels are highlighted. We classify the forms of these hydrogels by their size including macro-hydrogels, injectable hydrogels, and nano-hydrogels. Then, we summarize the various fabrication strategies for these hydrogels including chemical covalent bonding, physical conjugation, and the combination of chemical and physical interactions. Covalent bonding includes free radical polymerization of vinyl-containing components, amide bond formation reaction, Michael-type addition reaction, click-chemistry, divinyl sulfone crosslinking, and mussel-inspired coating. Hydrogels physically conjugated via host-guest interaction, electrostatic interaction, hydrogen bonding, and hydrophobic interaction are also discussed. Finally, we conclude with the challenges and future directions for the fabrication and the industrialization of heparin-based and heparin-inspired hydrogels. We believe that this review will attract more attention toward the design of heparin-based and heparin-inspired hydrogels, leading to future advancements in this emerging research field.
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Investigación Biomédica/métodos , Heparina/uso terapéutico , Hidrogeles/química , Heparina/farmacología , HumanosRESUMEN
In this paper, a photo-responsive bactericidal and bacteria-resistant membrane was successfully prepared via the integration of atom transfer radical polymerization (ATRP) and click chemistry. Azide-functionalized polycationic poly (N, N-dimethyl-N-(2-(methacryloyloxy)ethyl)-N-((2-nitrobenzyl)oxy)-2-oxoethanaminium bromide) (PDMAEMA-NBE) was synthesized by ATRP. Then, the PDMAEMA-NBE was clicked on alkynyl-functionalized polyethersulfone (PES) membrane surface, and proved by X-ray photoelectron spectrometer (XPS). Upon UV irradiation, the polycationic surface would switch to polyzwitterionic one. Before and after the irradiation, the zeta potentials of the surface altered from +14.7 to -3.8mV, and the water contact angle decreased from 64.0° to 52.7°. The polycationic surface exhibited excellent bactericidal property and the dead bacteria could detach from the polyzwitterionic surface induced by the subsequent UV irradiation. It demonstrated that the designing of photo-responsive membrane surface could be a new strategy for antibacterial adhesion.