Metal oxides include many important materials with various surface properties. For biomedical and analytical applications, it is desirable to engineer their biocompatible interfaces. Herein, a ...phosphocholine liposome (DOPC) and its headgroup dipole flipped counterpart (DOCP) were mixed with ten common oxides. Using the calcein leakage assay, cryo‐TEM, and ζ‐potential measurement, these oxides were grouped into three types. The type 1 oxides (Fe3O4, TiO2, ZrO2, Y2O3, ITO, In2O3, and Mn2O3) form supported bilayers only with DOCP. Type 2 (SiO2) forms supported bilayers only with DOPC; type 3 (ZnO and NiO) are cationic and damage lipid membranes. Magnetic Fe3O4 nanoparticles were further studied for conjugation of fluorophores, proteins, and DNA to the supported DOCP bilayers via lipid headgroup labeling, covalent linking, or lipid insertion. Delivery of the conjugates to cells and selective DNA hybridization were demonstrated. This work provides a general solution for coating the type 1 oxides with a simple mixing in water, facilitating applications in biosensing, separation, and nanomedicine.
A technical dream‐coat: Ten common metal oxide nanoparticles were classified into three groups based on their interaction with two related liposomes. Enveloping a magnetic iron oxide core with a lipid shell facilitates bioconjugation, biocompatibility, and delivery.
Natural hydrogels are promising scaffolds to engineer epidermis. Currently, natural hydrogels used to support epidermal regeneration are mainly collagen‐ or gelatin‐based, which mimic the natural ...dermal extracellular matrix but often suffer from insufficient and uncontrollable mechanical and degradation properties. In this study, a photocrosslinkable gelatin (i.e., gelatin methacrylamide (GelMA)) with tunable mechanical, degradation, and biological properties is used to engineer the epidermis for skin tissue engineering applications. The results reveal that the mechanical and degradation properties of the developed hydrogels can be readily modified by varying the hydrogel concentration, with elastic and compressive moduli tuned from a few kPa to a few hundred kPa, and the degradation times varied from a few days to several months. Additionally, hydrogels of all concentrations displayed excellent cell viability (>90%) with increasing cell adhesion and proliferation corresponding to increases in hydrogel concentrations. Furthermore, the hydrogels are found to support keratinocyte growth, differentiation, and stratification into a reconstructed multilayered epidermis with adequate barrier functions. The robust and tunable properties of GelMA hydrogels suggest that the keratinocyte laden hydrogels can be used as epidermal substitutes, wound dressings, or substrates to construct various in vitro skin models.
A photocrosslinkable, biodegradable, naturally derived hydrogel, gelatin methacrylamide, with tunable mechanical and degradation properties, is developed for skin tissue regeneration. The engineered hydrogels can support keratinocyte adhesion, proliferation, and differentiation to form a multilayered epidermis with barrier functions.
Herein, we report a highly efficient and practical method for pyridine‐derived heterobiaryl synthesis through palladium‐catalyzed electrophilic functionalization of easily available pyridine‐derived ...quaternary phosphonium salts. The nice generality of this reaction was goes beyond arylation, enabling facile incorporation of diverse carbon‐based fragments, including alkenyl, alkynyl, and also allyl fragments, onto the pyridine core. Notably, the silver salt additive is revealed to be of vital importance for the success of this transformation and its pivotal role as transmetallation mediator, which guarantees a smooth transfer of pyridyl group to palladium intermediate, is also described.
It takes two: By taking advantage of the synergistic interaction of a palladium catalyst and silver additive, a strategically novel synthetic method that enables the expedient site‐selective elaboration of pyridine derivatives was developed. The successful use of pyridylphosphonium salts as donors of a pyridyl anion equivalent greatly expands the range of competent nucleophilic coupling partners for palladium‐catalyzed cross‐coupling.
Development of natural protein-based fibrous scaffolds with tunable physical properties and biocompatibility is highly desirable to construct three-dimensional (3D), fully cellularized scaffolds for ...wound healing. Herein, we demonstrated a simple and effective technique to construct electrospun 3D fibrous scaffolds for accelerated wound healing using a photocrosslinkable hydrogel based on gelatin methacryloyl (GelMA). We found that the physical properties of the photocrosslinkable hydrogel including water retention, stiffness, strength, elasticity and degradation can be tailored by changing the light exposure time. We further observed that the optimized hydrogel fibrous scaffolds which were soft and elastic could support cell adhesion, proliferation and migration into the whole scaffolds, facilitating regeneration and formation of cutaneous tissues within two weeks. Such tunable characteristics of the fibrous GelMA scaffolds distinguished them from other reported substrates developed for reconstruction of wound defects including glutaraldehyde-crosslinked gelatin or poly (lactic-co-glycolic acid) (PLGA), whose physical and chemical properties were difficult to modify to allow cell infiltration into the 3D scaffolds for tissue regeneration. We anticipate that the ability to become fully cellularized will make the engineered GelMA fibrous scaffolds suitable for widespread applications as skin substitutes or wound dressings.
In present study, we generate three-dimensional photocrosslinkable gelatin (GelMA)-based fibrous scaffolds with tunable physical and biological properties by using a combined photocrosslinking/electrospinning approach. The developed GelMA fibrous scaffolds can not only support cell viability and cell adhesion, but also facilitate cell migration and proliferation, accelerating regeneration and formation of cutaneous tissues. In addition, the physical properties of the engineered fibrous GelMA hydrogel including water retention capability, mechanical properties and biodegradability can be tuned to accommodate different patients' needs, making it a promising candidate for skin tissue engineering.
Symmetry and topology are two fundamental aspects of many quantum states of matter. Recently new topological materials, higher-order topological insulators, were discovered, featuring ...bulk-edge-corner correspondence that goes beyond the conventional topological paradigms. Here we discover experimentally that the nonsymmorphic p4g acoustic metacrystals host a symmetry-protected hierarchy of topological multipoles: the lowest band gap has a quantized Wannier dipole and can mimic the quantum spin Hall effect, whereas the second band gap exhibits quadrupole topology with anomalous Wannier bands. Such a topological hierarchy allows us to observe experimentally distinct, multiplexed topological phenomena and to reveal a topological transition triggered by the geometry transition from the p4g group to the C
group, which demonstrates elegantly the fundamental interplay between symmetry and topology. Our study demonstrates that classical systems with controllable geometry can serve as powerful simulators for the discovery of novel topological states of matter and their phase transitions.
Mitochondrial dynamics plays an important role in tumour progression. However, how these dynamics integrate tumour metabolism in hepatocellular carcinoma (HCC) metastasis is still unclear.
The ...mitochondrial fusion protein mitofusin-1 (MFN1) expression and its prognostic value are detected in HCC. The effects and underlying mechanisms of MFN1 on HCC metastasis and metabolic reprogramming are analysed both in vitro and in vivo.
Mitochondrial dynamics, represented by constant fission and fusion, are found to be associated with HCC metastasis. High metastatic HCC displays excessive mitochondrial fission. Among genes involved in mitochondrial dynamics, MFN1 is identified as a leading downregulated candidate that is closely associated with HCC metastasis and poor prognosis. While promoting mitochondrial fusion, MFN1 inhibits cell proliferation, invasion and migration capacity both in vitro and in vivo. Mechanistically, disruption of mitochondrial dynamics by depletion of MFN1 triggers the epithelial-to-mesenchymal transition (EMT) of HCC. Moreover, MFN1 modulates HCC metastasis by metabolic shift from aerobic glycolysis to oxidative phosphorylation. Treatment with glycolytic inhibitor 2-Deoxy-D-glucose (2-DG) significantly suppresses the effects induced by depletion of MFN1.
Our results reveal a critical involvement of mitochondrial dynamics in HCC metastasis via modulating glucose metabolic reprogramming. MFN1 may serve as a novel potential therapeutic target for HCC.
Alkene hydrocarbonation reactions have been developed to supplement traditional electrophile-nucleophile cross-coupling reactions. The branch-selective hydroalkylation method applied to a broad range ...of unactivated alkenes remains challenging. Herein, we report a NiH-catalysed proximal-selective hydroalkylation of unactivated alkenes to access β- or γ-branched alkyl carboxylic acids and β-, γ- or δ-branched alkyl amines. A broad range of alkyl iodides and bromides with different functional groups can be installed with excellent regiocontrol and availability for site-selective late-stage functionalization of biorelevant molecules. Under modified reaction conditions with NiCl
(PPh
)
as the catalyst, migratory hydroalkylation takes place to provide β- (rather than γ-) branched products. The keys to success are the use of aminoquinoline and picolinamide as suitable directing groups and combined experimental and computational studies of ligand effects on the regioselectivity and detailed reaction mechanisms.
Photocatalytic hydrogen evolution can effectively alleviate the troublesome global energy crisis by converting solar energy into the chemical energy of hydrogen. In order to realize efficient ...hydrogen generation, a variety of semiconductor materials have been extensively investigated, including TiO2, CdS, g‐C3N4, metal‐organic frameworks (MOFs), and others. In recent years, to achieve higher photocatalytic performance and reach the level of large‐scale industrial applications, photocatalysts decorated with transition metal phosphides (TMPs) have shone brightly because of their low cost, stable physical and chemical properties, and substitution for precious metals of TMPs. This Review highlights the preparation methods and properties associated with photocatalysis of TMPs. Moreover, the H2 generation efficiency of photocatalysts loaded with TMPs and the roles of TMPs in catalytic systems are also studied systematically. Apart from being co‐catalysts, several TMPs can also serve as host catalysts to boost the activity of photocatalytic composites. Finally, the development prospects and challenges of TMPs are put forward, which is valuable for future researchers to expand the application of TMPs in photocatalytic directions and to develop more active photocatalytic systems.
H2 evolution: This Review highlights the preparation methods and properties of transition metal phosphides (TMPs). Moreover, the hydrogen evolution efficiency of photocatalysts loaded with TMPs and the roles of TMPs in catalytic systems are also studied systematically. In addition, several TMPs can also serve as host catalysts to boost the activity of photocatalytic composites. This work demonstrates the importance of TMPs in the photocatalytic conversion of solar energy into chemical energy.
Cyclopropene hydrofunctionalization has been a promising strategy for accessing multi‐substituted cyclopropanes; however, cyclopropene hydroalkylation remains underdeveloped. Herein, we report a ...low‐valent CoH‐catalyzed facial‐selective cyclopropene hydroalkylation to access multi‐substituted cyclopropanes. This reaction exhibits a broad substrate scope of alkyl halides and cyclopropenes and tolerates many functional groups. Moderate‐to‐good facial‐selectivity is obtained without any directing groups. Mechanism studies provide evidence that alkyl radicals are generated from alkyl halides and irreversible CoH insertion is responsible for the facial‐selectivity. Our preliminary exploration demonstrates that asymmetric cyclopropene hydroalkylation can be realized without conspicuous auxiliary groups.
Low‐valent CoH‐catalyzed facial‐selective cyclopropene hydroalkylation has been reported. The reaction works in the absence of any additional directing groups.
A smart, tumor‐trigged, controlled drug release using inorganic “caps” with CO3
2− functional groups in electrospun fibers is presented for inhibiting cancer relapse. When the drug‐loaded intelligent ...electrospun fibers encounter pathological acidic environments, the inorganic gates react with the acids and produce CO2 gas, which enables water penetration into the core of the fibers to induce rapid drug release.
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