Current approaches to fabrication of nSC composites for bone tissue engineering (BTE) have limited capacity to achieve uniform surface functionalization while replicating the complex architecture and ...bioactivity of native bone, compromising application of these nanocomposites for in situ bone regeneration. A robust biosilicification strategy is reported to impart a uniform and stable osteoinductive surface to porous collagen scaffolds. The resultant nSC composites possess a native‐bone‐like porous structure and a nanosilica coating. The osteoinductivity of the nSC scaffolds is strongly dependent on the surface roughness and silicon content in the silica coating. Notably, without the use of exogenous cells and growth factors (GFs), the nSC scaffolds induce successful repair of a critical‐sized calvarium defect in a rabbit model. It is revealed that topographic and chemical cues presented by nSC scaffolds could synergistically activate multiple signaling pathways related to mesenchymal stem cell recruitment and bone regeneration. Thus, this facile surface biosilicification approach could be valuable by enabling production of BTE scaffolds with large sizes, complex porous structures, and varied osteoinductivity. The nanosilica‐functionalized scaffolds can be implanted via a cell/GF‐free, one‐step surgery for in situ bone regeneration, thus demonstrating high potential for clinical translation in treatment of massive bone defects.
A biosilicification strategy is developed to provide a uniform and robust osteoinductive surface on porous natural collagen scaffolds. The resultant nanosilica–collagen (nSC) scaffolds possess topographical and chemical cues for superior in situ bone defect repair, without the use of exogenous cells or growth factors. This novel preparation of biomimetic bone scaffolds shows promising clinical applications in the treatment of bone defects.
A large number of SARS-related coronaviruses (SARSr-CoV) have been detected in horseshoe bats since 2005 in different areas of China. However, these bat SARSr-CoVs show sequence differences from SARS ...coronavirus (SARS-CoV) in different genes (S, ORF8, ORF3, etc) and are considered unlikely to represent the direct progenitor of SARS-CoV. Herein, we report the findings of our 5-year surveillance of SARSr-CoVs in a cave inhabited by multiple species of horseshoe bats in Yunnan Province, China. The full-length genomes of 11 newly discovered SARSr-CoV strains, together with our previous findings, reveals that the SARSr-CoVs circulating in this single location are highly diverse in the S gene, ORF3 and ORF8. Importantly, strains with high genetic similarity to SARS-CoV in the hypervariable N-terminal domain (NTD) and receptor-binding domain (RBD) of the S1 gene, the ORF3 and ORF8 region, respectively, were all discovered in this cave. In addition, we report the first discovery of bat SARSr-CoVs highly similar to human SARS-CoV in ORF3b and in the split ORF8a and 8b. Moreover, SARSr-CoV strains from this cave were more closely related to SARS-CoV in the non-structural protein genes ORF1a and 1b compared with those detected elsewhere. Recombination analysis shows evidence of frequent recombination events within the S gene and around the ORF8 between these SARSr-CoVs. We hypothesize that the direct progenitor of SARS-CoV may have originated after sequential recombination events between the precursors of these SARSr-CoVs. Cell entry studies demonstrated that three newly identified SARSr-CoVs with different S protein sequences are all able to use human ACE2 as the receptor, further exhibiting the close relationship between strains in this cave and SARS-CoV. This work provides new insights into the origin and evolution of SARS-CoV and highlights the necessity of preparedness for future emergence of SARS-like diseases.
Methotrexate (MTX) is an antiproliferative drug widely used to treat inflammatory diseases and autoimmune diseases. The application of percutaneous administration is hindered due to its poor ...transdermal penetration. To reduce side effects and enhanced percutaneous delivery of MTX, novel methotrexate (MTX)-loaded micelles prepared with a amphiphilic cationic material,
-dimethyl-(
-di-stearoyl-1-ethyl)1,3-diaminopropane (DMSAP), was designed.
DMSAP was synthesized via three steps using simple chemical agents. H nuclear magnetic resonance and mass spectroscopy were used to confirm the successful synthesis of DMSAP. A safe and non-toxic phosphatidylcholine, soybean phosphatidylcholine (SPC), was added to DMSAP at different ratios to form P/D-micelles. Then, MTX-entrapped micelles (M/P/D-micelles) were prepared by electrostatic adsorption. The physicochemical properties and blood stability of micelles were examined thoroughly. In addition, the transdermal potential of the micelles was evaluated by permeation experiments.
In aqueous environments, DMSAP conjugates could self-assemble spontaneously into micelles with a low critical micelle concentration (CMC) of 0.056 mg/mL. Stable, spherical MTX-entrapped micelles (M/P/D-micelles) with a size of 100-120 nm and high zeta potential of +36.26 mV were prepared. In vitro permeation studies showed that M/P/D-micelles exhibited superior skin permeability and deposition of MTX in the epidermis and dermis compared with that of free MTX.
These special novel cationic M/P/D-micelles can enhance the permeability of MTX and are expected to be a promising percutaneous delivery system for therapy skin diseases.
Although the Turing structures, or stationary reaction‐diffusion patterns, have received increasing attention in biology and chemistry, making such unusual patterns on inorganic solids is ...fundamentally challenging. We report a simple cation exchange approach to produce Turing‐type Ag2Se on CoSe2 nanobelts relied on diffusion‐driven instability. The resultant Turing‐type Ag2Se‐CoSe2 material is highly effective to catalyze the oxygen evolution reaction (OER) in alkaline electrolytes with an 84.5 % anodic energy efficiency. Electrochemical measurements show that the intrinsic OER activity correlates linearly with the length of Ag2Se‐CoSe2 interfaces, determining that such Turing‐type interfaces are more active sites for OER. Combing X‐ray absorption and computational simulations, we ascribe the excellent OER performance to the optimized adsorption energies for critical oxygen‐containing intermediates at the unconventional interfaces.
A novel Turing‐type Ag2Se‐CoSe2 structure has been synthesized, which possesses rich Ag2Se‐CoSe2 interfaces, exhibiting a 221 mV overpotential at a current density of 10 mA cm−2 in 0.1 M KOH electrolyte with a high anodic energy efficiency of 84.5 %.
Electrosynthesis of hydrogen peroxide (H2O2) in the acidic environment could largely prevent its decomposition to water, but efficient catalysts that constitute entirely earth‐abundant elements are ...lacking. Here we report the experimental demonstration of narrowing the interlayer gap of metallic cobalt diselenide (CoSe2), which creates high‐performance catalyst to selectively drive two‐electron oxygen reduction toward H2O2 in an acidic electrolyte. The enhancement of the interlayer coupling between CoSe2 atomic layers offers a favorable surface electronic structure that weakens the critical *OOH adsorption, promoting the energetics for H2O2 production. Consequently, on the strongly coupled CoSe2 catalyst, we achieved Faradaic efficiency of 96.7 %, current density of 50.04 milliamperes per square centimeter, and product rate of 30.60 mg cm−2 h−1. Moreover, this catalyst shows no sign of degradation when operating at −63 milliamperes per square centimeter over 100 hours.
A strategy that narrows the interlayer distance of cobalt diselenide (CoSe2) is reported, which enables strong coupling between CoSe2 monolayers. The strongly coupled CoSe2 can catalyze electrosynthesis of H2O2 in acidic media efficiently, which yields Faradaic efficiency of 96.7 %, current density of 50.04 mA cm−2, and product rate of 30.60 mg cm−2 h−1, outperforming all catalysts reported previously in acidic environments.
The clinic applications of bioabsorbable magnesium (Mg) and its alloys have been significantly restricted owing to their poor corrosion resistance. Besides elemental alloying, surface modification ...and functionality is a major approach to increasing corrosion resistance for magnesium alloys. This article reviews the cutting-edge advances and progress of biodegradable surface coatings upon Mg alloys over the last decades, aims to build up a knowledge framework of surface modification on biodegradable Mg alloys. A considerable number of conversion, deposition, mechanical and functional coatings and their preparation methods are discussed. The emphasis has been placed on the composition of chemical conversion and deposited coatings to overcome the disadvantages of adhesion, corrosion resistance and biocompatibility of a single coating for biomedical materials. The issues have been addressed on the integration of the structural and functional factors of the composite coatings.
A considerable challenge in the conversion of carbon dioxide into useful fuels comes from the activation of CO2 to CO2.− or other intermediates, which often requires precious‐metal catalysts, high ...overpotentials, and/or electrolyte additives (e.g., ionic liquids). We report a microwave heating strategy for synthesizing a transition‐metal chalcogenide nanostructure that efficiently catalyzes CO2 electroreduction to carbon monoxide (CO). We found that the cadmium sulfide (CdS) nanoneedle arrays exhibit an unprecedented current density of 212 mA cm−2 with 95.5±4.0 % CO Faraday efficiency at −1.2 V versus a reversible hydrogen electrode (RHE; without iR correction). Experimental and computational studies show that the high‐curvature CdS nanostructured catalyst has a pronounced proximity effect which gives rise to large electric field enhancement, which can concentrate alkali‐metal cations resulting in the enhanced CO2 electroreduction efficiency.
The needle has landed: CdS nanostructures with sharp tips can generate large electric fields that lead to increased CO2 concentrations for CO2‐to‐CO conversion. The localized electric fields are significantly enhanced when two nanoneedles are in close proximity. These advantages result in CO2 electrocatalytic reduction with a 95.5±4.0 % CO Faraday efficiency.
Conspectus High-nuclearity cluster-type metal complexes are a unique class of compounds, many of which have aesthetically pleasing molecular structures. Their interesting physical and chemical ...properties arise primarily from the electronic and/or magnetic interplay between the component metal ions. Among the extensive studies in the past two decades, those on lanthanide-containing clusters, lanthanide-exclusive or heterometallic with transition metal elements, are most notable. The research was driven by both the synthetic challenges for these generally elusive species and their intriguing magnetic properties, which are useful for the development of energy-efficient and environmentally friendly magnetic cooling technologies. Our efforts in this vein have been concentrated on developing rational synthetic methods for high-nuclearity lanthanide-containing clusters. By means of the now widely adopted approach of “ligand-controlled hydrolysis” of lanthanide ions, a great variety of cluster-type lanthanide hydroxide complexes had been prepared in the first half of this developing period (1999–2006). In this Account, our efforts since 2007 are summarized. These include (1) further development of synthetic strategies in order to expand the ligand scope and/or to increase the nuclearity (>25) of the cluster species and (2) magnetic studies pertinent to the pursuit of materials with a large magnetocaloric effect (MCE). Specifically, with the hope of expanding the family of ligands and producing clusters of previously unknown structures, we tested under hydrothermal or solvothermal conditions the use of readily available yet not commonly used ligands for controlling lanthanide hydrolysis; such ligands, carboxylates as mundane examples, tend to form insoluble complexes prior to any possible hydrolysis. We have also validated the use of preformed transition metal complexes as metalloligands for subsequent control of lanthanide hydrolysis toward heterometallic 3d–4f clusters. Furthermore, we demonstrated using ample examples that the presence of small anions as templates is essential to the assembly of high-nuclearity lanthanide-containing clusters and that maintaining a low concentration of the anion template(s) is a key to such success. It has been found that slow production/release of such anion templates by in situ ligand decomposition or absorption of atmospheric CO2 is effective in preventing precipitation of their lanthanide salts, allowing not only controllable lanthanide hydrolysis but also gradual and modular assembly of the giant cluster species. Magnetic studies targeting potential applications of such clusters as molecular magnetic coolers have also been conducted. The results are summarized in the second portion of this Account in an effort to establish a certain magneto–structure relationship. Of particular relevance is the possible correlation between MCE (evaluated using the isothermal magnetic entropy change, −ΔS M) and magnetic density, and the intracluster antiferromagnetic exchange coupling. We have also made some preliminary attempts at preparing processable and practically useful materials in the form of a monodisperse core–shell nanostructure. We succeeded in encapsulating a single nanosized heterometallic molecular cluster in a nanoshell of silica. It was found that such passivation not only helped stabilize the cluster but also reduced the magnetic interactions between individual clusters. These effects are reflected in the slightly enhanced value of −ΔS M for the core–shell composite over the parent unprotected cluster.
Selective and efficient catalytic conversion of carbon dioxide (CO2) into value-added fuels and feedstocks provides an ideal avenue to high-density renewable energy storage. An impediment to enabling ...deep CO2 reduction to oxygenates and hydrocarbons (e.g., C2+ compounds) is the difficulty of coupling carbon–carbon bonds efficiently. Copper in the +1 oxidation state has been thought to be active for catalyzing C2+ formation, whereas it is prone to being reduced to Cu0 at cathodic potentials. Here we report that catalysts with nanocavities can confine carbon intermediates formed in situ, which in turn covers the local catalyst surface and thereby stabilizes Cu+ species. Experimental measurements on multihollow cuprous oxide catalyst exhibit a C2+ Faradaic efficiency of 75.2 ± 2.7% at a C2+ partial current density of 267 ± 13 mA cm–2 and a large C2+-to-C1 ratio of ∼7.2. Operando Raman spectra, in conjunction with X-ray absorption studies, confirm that Cu+ species in the as-designed catalyst are well retained during CO2 reduction, which leads to the marked C2+ selectivity at a large conversion rate.
Well-established surveillance and monitoring systems for respiratory viruses need to be improved, and epidemiological data on respiratory viruses in China are scarce. This study aimed to investigate ...the epidemiological characteristics of respiratory viruses among hospitalized children aged ≤2 years with acute respiratory tract infections (ARTIs) in Xiamen, China, from October 2014 to September 2017. The clinical records of 7,248 children hospitalized for ARTIs were retrospectively analyzed. Respiratory syncytial virus (RSV) (22.3%) was the most common virus among hospitalized children aged ≤2 years, followed by parainfluenza (5.0%), adenovirus (3.5%), and influenza (1.7%). RSV-infected children had a higher disease burden, including a higher intensive care unit (ICU) admission rate (12.7%) and higher hospital charges ($635.36). Particularly, infants aged <6 months had the highest risk of RSV infection (odds ratio = 2.4; 95% CI, 1.9–2.9) and a higher ICU admission rate (12.1% vs. 4.5%, 4.6%) and hospital cost ($923.3 vs. $785.5, $811.7) than the other age groups. Therefore, infants aged 0–6 months, particularly premature infants and children with congenital diseases, should receive more attention. There is an urgent need to develop effective immunization strategies to protect these infants during the first 6 months of life and in the RSV season.
PDF
