Latest ArticlesCarbon-based fluorescent nanomaterials have gained much attention in recent years. In this work, green-photoluminescent carbon nanodots (CNDs; also termed carbon dots, CDs) with amine termination were synthesized via the hydrothermal treatment of amine-containing spermine and rose bengal (RB) molecules. The CNDs have an ultrasmall size of ~2.2 nm and present bright photoluminescence with a high quantum yield of ~80% which is possibly attributed to the loss of halogen atoms (Cl and I) during the hydrothermal reaction. Different from most CNDs which have multicolor fluorescence emission, the as-prepared CNDs possess excitation-independent emission property, which can avoid fluorescence overlap with other fluorescent dyes. Moreover, the weakly basic amine-terminated surface endows the CNDs with the acidotropic effect. As a result, the CNDs can accumulate in the acidic lysosomes after cellular internalization and can serve as a favorable agent for lysosome imaging. Besides, the CNDs have a negligible impact on the lysosomal morphology even after 48 h incubation and exhibit excellent biocompatibility in the used cell models.
The wide-spreading SARS-CoV-2 virus has put the world into boiling water for more than a year, however pharmacological therapies to act effectively against coronavirus disease 2019 (COVID-19) remain elusive. Chloroquine (CQ), an antimalarial drug, was found to exhibit promising antiviral activity in vitro and in vivo at a high dosage, thus CQ was approved by the FDA for the emergency use authorization (EUA) in the fight against COVID-19 in the US, but later was revoked the EUA status due to the severe clinical toxicity. Herein, we show that supramolecular formulation of CQ by a macrocyclic host, curcurbit[7]uril (CB[7]), reduced its non-specific toxicity and improved its antiviral activity against coronavirus, working in synergy with CB[7]. CB[7] was found to form 1:1 host-guest complexes with CQ, with a binding constant of ~104 L/mol. The CQ-CB[7] formulation decreased the cytotoxicity of CQ against Vero E6 and L-02 cell lines. In particular, the cytotoxicity of CQ (60 μmol/L) against both Vero E6 cell line and L-02 cell lines was completely inhibited in the presence of 300 μmol/L and 600 μmol/L CB[7], respectively. Furthermore, the CB[7] alone showed astonishing antiviral activity in SARS-CoV-2 infected Vero E6 cells and mouse hepatitis virus strain A59 (MHV-A59) infected N2A cells, and synergistically improved the antiviral activity of CQ-CB[7], suggesting that CB[7]-based CQ formulation has a great potential as a safe and effective antiviral agent against SARS-CoV-2 and other coronavirus.
Ozone (O3) plays essential roles in stratosphere and helps reduce the amount of harmful ultraviolet arriving the Earth's surface. However, O3 is also a strong oxidant and causes troubles to human health in troposphere, especially in the confined space, such as indoor environment. Recently, O3 abatement materials have become research hotspots due to the urgent environmental demands. Catalysis is a facile strategy that can eliminate indoor airborne O3 efficiently and economically. Thus, this review summarizes the recent progresses of O3 decomposition catalysts. The catalysts covered here are categorized as follows: zeolite, metal organic frameworks (MOFs), metal oxides, noble metals. Manganese-based catalysts display higher efficiency and are mainly discussed. Generally, the active sites of O3 decomposition catalysts are described as Lewis acid sites (e.g., zeolite), metal sites (e.g., MOFs), oxygen vacancy sites (e.g., MnO2) in the previous work. In this review, we ascribe all the active sites to unsaturated metal sites and their Lewis acidity. Possible evidence from the experimental and theoretical perspectives are proposed. Furthermore, the strategy to circumvent deactivation caused by peroxides (O22-) accumulation and water molecular competition are also elaborated. Finally, perspective is presented on the challenges and opportunities of exploring existing and new O3 decomposition catalysts.
In this research, a novel bird nest-like zinc oxide (BN-ZnO) nanostructures were prepared by a simple solvothermal method. A sensitive electrochemical glucose biosensor was for the first time developed based on the immobilization of glucose oxidase (GOx) on nanostructured BN-ZnO modified electrode. The BN-ZnO nanostructure and the resultant biosensor were characterized by scanning electron microscope, X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, and electrochemical impedance spectroscopy. BN-ZnO nanostructures have large specific surface area and can load large amounts of GOx molecules. Meanwhile, BN-ZnO provides an excellent microenvironment to retain the native bioactivity of enzymes and to promote direct electron transfer between GOx and electrode surface. The proposed biosensor shows a wide linear range of 0.005–1.6 mmol/L, high sensitivity of 15.6 mAL mol−1 cm−2 with a low detection limit of 0.004 mmol/L. The resulting biosensor also shows excellent selectivity, acceptable stability and reproducibility, and can be successfully applied in the detection of glucose in human serum samples at −0.37V.
Codelivery of drugs by drug carriers is a promising strategy against several diseases such as infections and cancer. However, traditional drug carriers are typically characterized by low drug payload, limiting their treatment efficacy. Using nanocrystals of insoluble drug as carriers, a carrier free platform was developed previously to deliver a second insoluble drug for codelivery. To extend the concept, we hypothesized, herein, that the platform allows for codelivery of hydrophobic and hydrophilic drugs using a cocrystalization-like strategy. To obtain proof-of-concept, paclitaxel (PTX), an insoluble chemotherapeutic agent, and dichloroacetic acid (DCA), a water-soluble inhibitor of pyruvate dehydrogenase kinase, were utilized as model drugs. PTX-DCA hybrid nanocrystals (PTX-DCA NCs) were prepared by anti-solvent precipitation and characterized. Their in vitro antitumor activity against cancer cells was evaluated. PTX-DCA NCs prepared from the optimized formulation had a diameter of 160 nm and a rod-shape morphology and possessed encapsulated efficacy of approximately 30% for DCA. The use of the hybrid crystals enabled synergy to kill cancer cells, in particular in PTX-resistant cells in a dose-dependent pattern. In conclusion, by using a cocrystalization-like strategy, a hydrophilic drug can be formulated into a drug's nanocrystal for codelivery.
Discrimination of glycoproteins and cell types is a significant but difficult issue. Herein, we presented a novel fluorescence sensor array for the detection and identification of glycoproteins and cancer cells based on the specific affinity between boronic acid-containing carbon dots (BA-CDs) and cis-diol residues of polysaccharides. The differential binding affinity of three BA-CDs to various glycoproteins resulted in a different fluorescence turn-on signal pattern caused by aggregation-enhanced emission (AEE), along with negligible response from other proteins. Therefore, BA-CDs encompassing sensing elements and signal indicator into one can enable a fast and accurate discrimination of glycoproteins with simple and easy operation. Seven glycoproteins could be well discriminated at a very low concentration of 10 nmol/L. The discriminating capability of glycoproteins is not sacrificed in both human urine and serum. Notably, different glycoprotein compositions of cancer cells provide more recognizable features for identification of cancer cells, comparing to the total protein. Five cell types could be identified in 15 min at a low concentration of 1000 cells/mL. This method is fast, accurate, and easy operation, and has a potential application in cancer diagnosis.
Soft and wet actuator systems have attracted great attention in some applications, such as assistive technologies for rehabilitation, training and regenerative biomedicines. Three-dimensional (3D) printing methods have realized the rapid fabrication of complex structures without the need for expensive dies or post processing. In this review, a comprehensive description is presented on stimuli-responsive hydrogels fabricated by light-responsive and extrusion-based 3D printing technologies. Mechanisms of actuations have been introduced based on stimuli types. As the most common method for 3D printed hydrogel actuators, direct-ink-writing has been discussed, including the two printing parameters of resolution and rheology. In addition, applications of 3D printed hydrogel actuators are presented followed by introductions of recent contributions on enhancing the toughness of 3D printed hydrogel and robust design tools, such as finite element analysis and artificial intelligence.
Advanced chemotherapy strategies are in urgent demand for improving anticancer efficacy. Herein, a water-soluble pillar[6]arene (WP6A) was used to load chemotherapeutic agent pemetrexed (PMX) by forming direct host-guest inclusion, which is beneficial for decreasing cytotoxicity of PMX on BEAS-2B cells. NMR and florescence titration served to confirm the complexation between WP6A and ATP with higher affinity [(5.67 ± 0.31) × 105 L/mol], favoring competitive replacement of PMX. Complexation ATP by WP6A effectively prevented ATP from being hydrolyzed in presence of alkaline phosphatase. The formed host-guest complex was further used to block the efflux pump by cutting off energy source from ATP hydrolysis, which was accompanied with releasing PMX to produce synergistic enhancement of anticancer performance towards A549 cells. This supramolecular strategy would also be extended to other clinical chemotherapeutic agents and it was expected to provide salutary profits for cancer patients.
Single atom catalyst (SAC) refers to a novel catalyst with the active metal atoms individually anchored on the support. Single atom catalysts present the unique appeal due to the high atomic availability and specific activity, as well as the high pathway selectivity. Herein, we summarized the classification, preparation, characterization, and application of single atom catalysts. Finally, the current bottlenecks and the outlooks of the SAC research are discussed.
In this study, Si-doped ferrihydrite (Si-Fh) was successfully synthesized by a simple coprecipitation method for removal of heavy metals in water. Subsequently, the physicochemical properties of Si-Fh before and after adsorption were further studied using several techniques. The Si-Fh exhibited good adsorption capacity for heavy metal ions such as Pb(Ⅱ) and Cd(Ⅱ). The maximum adsorption capacities of lead and cadmium are respectively 105.807, 37.986mg/g. The distribution coefficients of the materials for Pb(Ⅱ) and Cd(Ⅱ) also showed a great affinity (under optimal conditions). Moreover, it was found that the adsorption fit well with the Freundlich isotherm and pseudo-second-order kinetic model which means this was a chemical adsorption process. It can be conducted from both characterization and model results that adsorption of Pb(Ⅱ) and Cd(Ⅱ) was mainly through the complexation interaction of abundance oxygen functional groups on the surface of Si-Fh. Overall, the Si-Fh adsorbents with many superiorities have potential for future applications in the removal of Pb(Ⅱ) and Cd(Ⅱ) from wastewater.
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