Latest ArticlesChemodynamic therapy (CDT) has attracted tremendous interest in cancer therapy because it is independent of oxygen and photoirradiation. However, the therapeutic efficacy of CDT is restricted by insufficient H2O2 levels in tumor cells. Herein, employing endogenous GSH as a template and cationic polymeric chitosan (CS) as crosslinker and stabilizer exhibiting easy cell uptake, red luminescent gold nanoclusters (denoted CS-GSH@AuNCs) were successfully synthesized in HeLa cells. The in situ synthesized CS-GSH@AuNCs exhibited both superoxidase dismutase (SOD) and peroxidase (POD)-like activity, which could promote the production of H2O2 from superoxide anion radicals (O2·−) and then ·OH. The combination of GSH elimination and H2O2 elevation boosted the generation of ·OH, which could trigger cancer cell apoptosis and death. The enzyme-like activity of CS-GSH@AuNCs could be effectively activated under acidic conditions, and showed a high killing effect on tumor cells but minimal toxicity to normal cells. The developed GSH consumption and ·OH promotion theranostic platform is an innovative route for enhanced CDT by the amplification of oxidative stress.
Magnetic particles (MPs) are the most widely used commercialized engineering particles, which gained great success in various biological applications. Inspired by their intrinsic Fe isotope composition, we discovered a commercialized MPs-internal standard's novel function to realize the accurate quantification of biomolecules. The bioassay of carcinoembryonic antigen (CEA) was chosen as a modal system. The Fe isotope in MPs and Au isotope in report probes were simultaneously and sensitively detected by the elemental mass spectrometry. 197Au/57Fe isotopic ratios and CEA concentrations showed good linearity in the range of 0.6–300 ng/mL, with a detection limit of 0.09 ng/mL (3σ). The accuracy and precision of the proposed MPs-based immunoassay were greatly improved, by eliminating potential MPs loss during magnetic separation and absolute intensity fluctuations. Considering the exceptional availability and universality of commercialized MPs, the proposed method might open a new avenue for MPs' biological applications.
Due to the technology limitation and inferior deNOx efficiency of urea selective catalytic reduction (SCR) catalysts at low temperatures, passive NOx adsorber (PNA) for decrease of NOx, CO and hydrocarbons (HCs) during "cold start" of vehicles was proposed to meet the further tighten NOx emission regulations in future. Among them, Pd modified zeolite PNA materials have received more attention because of their excellent NOx storage capacity, anti-poisoning and hydrothermal stability and since Pd/zeolite PNA was proposed, a variety of advanced characterization methods have been applied to investigate its adsorption behavior and structure-performance relationship. The comprehension of the active sites and adsorption chemistry of Pd/zeolite PNA was also significantly improved. However, there are few reviews that systematically summarize the recent progress and application challenges in atomic-level understanding of this material. In this review, we summarized the latest research progress of Pd/zeolite PNA, including active adsorption sites, adsorption mechanism, material physicochemical properties, preparation methods, storage and release performance and structure-performance relationships. In addition, the deactivation challenges faced by Pd/zeolite PNA in practical applications, such as chemical poisoning, high temperature hydrothermal aging deactivation, etc., were also discussed at the micro-level, and some possible effective countermeasures are given. Besides, some possible improvements and research hotspots were put forward, which could be helpful for designing and constructing more efficient PNA materials for meeting the ultra-low NOx emission regulation in the future.
An inexpensive Fe doped aluminoborate consisted of 18% Fe in PKU-1 material that exhibits high selectivity of 4-hydroxymethy-2,2-dimethyl-1,3-dioxolane (Solketal, 98.3%), considerable activity (TOF 51.7 h-1), and recyclable ability in the ketalization of glycerol to Solketal with acetone at 318 K has been developed. Our study demonstrated that the structure of Fe (less agglomerated iron species vs. FeOx clusters) can be tuned by changing Fe loading in the PKU-1 material, which correlated well with experimental observations. Furthermore, the surface boron sites were promoted by iron loading and behaved as Lewis-acid sites to facilitate the reaction process of glycerol ketalization, while the Solketal selectivity was closely related with the structure of iron species in PKU-1, which was proved by kinetic studies, density function theory (DFT) calculations, and a series of spectroscopy studies. This investigation demonstrates that the surface B sites can play important roles in the reaction instead of being spectators.
Spin-crossover (SCO) complexes with multiple spin states are promising candidates for high-order magnetic storage and multiple switches. Here, by employing the N, Nʹ-4-dipyridyloxalamide (dpo) ligand, we synthesize two Hofmann-type metal-organic frameworks (MOFs) [Fe(dpo){Ag(CN)2}2]·3DMF (1) and [Fe(dpo){Ag(CN)2}2]·0.5MeCN·2DEF (2), which exhibit guest dependent four-step SCO behaviors with the sequences of LS → ~LS2/3HS1/3 → LS1/2HS1/2 → ~LS3/10HS7/10 → HS and LS → ~LS2/3HS1/3 → LS1/2HS1/2 → ~LS1/4HS3/4 → HS, respectively. Therefore, the incorporation of hydrogen-donating/hydrogen-accepting groups into the Hofmann-type MOFs may effectively explore the multi-step SCO materials by tuning hydrogen-bonding interactions.
The unique heterojunction photocatalyst of graphite carbon nitride (g-C3N4) modified ultrafine TiO2 (g-C3N4/TiO2) was successfully fabricated by electrochemical etching and co-annealing method. However, the effects of various environmental factors on the degradation of TC by g-C3N4/TiO2 and the internal reaction mechanism are still unclear. In this study, the effects of initial pH, anions, and cations on the photocatalytic degradation of tetracycline hydrochloride (TC) by g-C3N4/TiO2 were systematically explored, and the scavenging experiment and intermediate detection were conducted to better reveal the mechanism on photocatalytic degradation of TC. The results showed that the removal efficiency of photocatalytic degradation of TC by g-C3N4/TiO2 could reach 99.04% under Xenon lamp irradiation within 120 min. The unique g-C3N4/TiO2 heterojunction photocatalyst showed excellent photocatalytic performance for the degradation of TC at pH 3~7, and possesses outstanding anti-interference ability to NO3−, Cl−, Na+, Ca2+ and Mg2+ ions in natural waters during the photocatalytic degradation TC process. Superoxide radicals (O2·−) and hydroxyl radicals (·OH) were proved as the main reactive species for TC degradation, and the possible mechanism of the unique photocatalytic system for g-C3N4/TiO2 was also proposed. The above results can provide a reliable basis and theoretical guidance for the design and application of visible photocatalyst with high activity to degrade the actual wastewater containing TC.
Highly dispersed silicotungstic acid-derived WO3 composited with ZrO2 supported on SBA-15 (WZ/SBA-15) as an ordered mesoporous solid acid catalyst was prepared via a facile incipient wetness impregnation (IWI) method that active ingredients, ZrO2 and WO3, were impregnated into the channels of SBA-15 simultaneously with a subsequent calcination process. The relationship between catalyst nature and performance was explored by high resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), FT-IR, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), N2 adsorption-desorption, NH3 temperature-programmed desorption (NH3-TPD), and FT-IR of pyridine adsorption (Py-IR) characterization techniques. The catalytic performance of W12Z15/SBA-15 is not only greater than that of single component solid acid catalysts, WO3/SBA-15 and ZrO2/SBA-15, but also W12/Z15/SBA-15 prepared by impregnating active ingredients, ZrO2 and WO3, into SBA-15 in sequence. The outstanding performance of W12Z15/SBA-15 is derived from the strong interaction between ZrO2 and WO3, which results in more acid sites, and relatively high specific surface area, large pore volume, and ordered mesoporous structure of SBA-15. The characterization and reaction results clearly demonstrate that the synergy of ZrO2 and WO3 has a clear boost for the alkenylation. The optimized W12Z15/SBA-15-500 achieves a 99.4% conversion of phenylacetylene and a 92.3% selectivity of main product α-arylstyrene for the alkenylation of p-xylene with phenylacetylene, with very low level of oligomers producing at the same time. Moreover, W12Z15/SBA-15-500 shows excellent catalytic stability and regeneration. Therefore, W12Z15/SBA-15-500 is a promising solid acid catalyst for the alkenylation.
Sodium-ion batteries (SIBs) are promising alternatives to lithium-ion batteries (LIBs) for large-scale energy storage considering the abundance and low cost of Na-containing resources. However, the energy density of SIBs has been limited by the typically low specific capacities of traditional intercalation-based cathodes. Metal fluorides, in contrast, can deliver much higher capacities based on multi-electron conversion reactions. Among metal fluorides, CuF2 presents a theoretical specific capacity as high as 528 mAh/g while its Na-ion storage mechanism has been rarely reported. Here, we report CuF2 as a SIB cathode, which delivers a high capacity of 502 mAh/g but suffers from poor electrochemical reversibility. As a solution, we adjust the cell configuration by inserting a carbon-coated separator, which hinders the transportation of dissolved Cu ions and improves the reversibility of the CuF2 cathode. By using in-situ XRD measurements and theoretical calculation, we propose that a one-step conversion reaction occurs during the discharge process, and a reconversion reaction competes with the oxidization of Cu to dissolved Cu ion during the charge process.
Numerous approaches have been used to modify graphitic carbon nitride (g-C3N4) for improving its photocatalytic activity. In this study, we demonstrated a facial post-calcination method for modified graphitic carbon nitride (g-C3N4-Ar/Air) to direct tuning band structure, i.e., bandgap and positions of conduction band (CB)/valence band (VB), through the control of atmospheric condition without involving any additional elements or metals or semiconductors. The synthesized g-C3N4-Ar/Air could efficiently degrade sulfamethazine (SMT) under simulated solar light, i.e., 99.0% removal of SMT with rate constant k1 = 2.696 h−1 within 1.5 h (4.9 times than pristine g-C3N4). Material characterizations indicated that the damaged/partial-collapsed structure and decreased nanosheet-interlayer distance for g-C3N4-Ar/Air resulted in the shift of band structure due to the denser stacking of pristine g-C3N4 through oxidative exfoliation and planarization by air calcination. In addition, the bandgap of g-C3N4-Ar/Air was slightly shrunk from 2.82 eV (pristine g-C3N4) to 2.79 eV, and the CB was significantly upshifted from −0.44 eV (pristine g-C3N4) to −0.81 eV, suggesting the powerful ability for donating the electrons for O2 to form •O2−. Fukui index (f –) based on theoretical calculation indicated that the sites of SMT molecule with high values, i.e., N9, C4 and C6, preferred to be attacked by •O2− and •OH, which is confirmed by the intermediates' analysis. The tuning method for graphitic carbon nitride provides a simple approach to regulate the charge carrier lifetime then facilitate the utilization efficiency of solar light, which exhibits great potential in efficient removal of emerging organic contaminants from wastewater.
The regeneration of the injured nerve and recovery of its function have brought attention in the medical field. Electrical stimulation (ES) can enhance the cellular biological behavior and has been widely studied in the treatment of neurological diseases. Microfluidic technology can provide a cell culture platform with the well-controlled environment. Here a novel microfluidic/microelectrode composite microdevice was developed by embedding the microelectrodes to the microfluidic platform, in which microfluidics provided a controlled cell culture platform, and ES promoted the NSCs proliferation. We performed ES on rat neural stem cells (NSCs) to observe the effect on their growth, differentiation, proliferation, and preliminary explored the ES influence on cells in vitro. The results of immunofluorescence showed that ES had no significant effect on the NSCs specific expression, and the NSCs specific expression reached 98.9% ±0.4% after three days of ES. In addition, ES significantly promoted cell growth and the cell proliferation rate reached 49.41%. To conclude, the microfluidic/microelectrode composite microdevice can play a positive role in the nerve injury repair and fundamental research of neurological diseases.
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