Due to the amphiphilic nature of phospholipids in the cell membrane, the amphipathicity of the nanomedicine plays a crucial role in the endocytosis. However, limited biological characterization methods restrict the study of the state of nanoparticles with different amphiphilicities on cell membranes. The understanding of interaction of amphiphilic particle with cell membrane is still lacking. Herein, by combining the dissipative particle dynamics (DPD) with the framework construction of mesoporous silica nanoparticles (MSNs), we demonstrate the enhanced endocytosis induced by the hydrophobicity. DPD results confirm that the presence of hydrophobic groups on the surface of nanoparticles can disturb the integrity of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) membrane and induce activation of phospholipids to a higher energy level, thereby facilitating the wrapping of nanoparticles. To validate the simulation findings, uniform MSNs with hydrophilic pure silica framework and two types of amphiphilic MSNs with varying hydrophilic organic groups in the framework are rationally synthesized by using different silane precursors. The obtained three kinds of MSNs show similar diameter (~ 100 nm) and mesopores (~ 2 nm), but distinct hydrophobicity/hydrophilicity ratio. The phenyl-bridged MSN with a carbon content of 27.1% exhibits enhanced cellular uptake, consistent with the theoretical simulation results. This work sheds light on how the surface amphipathicity influences endocytosis through the interaction with cell membrane.
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Hollow TiO2–X porous microspheres consisted of numerous well-crystalline nanocrystals with superior structural integrity and robust hollow interior were synthesized by a facile sol-gel template-assisted approach and two-step carbonprotected calcination method, together with hydrogenation treatment. They exhibit a uniform diameter of ~470 nm with a thin porous wall shell of ~50 nm in thickness. The Brunauer-Emmett-Teller (BET) surface area and pore volume are ~19 m2/g and 0.07 cm3/g, respectively. These hollow TiO2–X porous microspheres demonstrated excellent lithium storage performance with stable capacity retention for over 300 cycles (a high capacity of 151 mAh/g can be obtained up to 300 cycles at 1 C, retaining 81.6% of the initial capacity of 185 mAh/g) and enhanced rate capability even up to 10 C (222, 192, 121, and 92.1 mAh/g at current rates of 0.5, 1, 5, and 10 C, respectively). The intrinsic increased conductivity of the hydrogenated TiO2 microspheres and their robust hollow structure beneficial for lithium ion-electron diffusion and mitigating the structural strain synergistically contribute to the remarkable improvements in their cycling stability and rate performance.
The rational design and precise synthesis of multifunctional hybrid nanostructures with a tailored active core and a large, dendritic, modified mesoporous structured shell can promote catalysis, energy storage, and biological applications. Here, an oil-water biphase stratification coating strategy has been developed to prepare monodisperse magnetic dendritic mesoporous silica core-shell structured nanospheres. These sophisticated Fe3O4@SiO2@dendritic-mSiO2 nanospheres feature large dendritic open pores (2.7 and 10.3 nm). Significantly, the silica shells can be converted into dendritic mesoporous aluminosilicate frameworks with unchanged porosity, a Si/Al molar ratio of 14, and remarkably strong acidic sites, through a post-synthesis approach. In addition, the resultant magnetic dendritic mesoporous aluminosilicate nanospheres exhibit outstanding properties and promising application in phosphate removal from wastewater.
A facile one-pot method has been developed to synthesize uniform gold@mesoporous silica nanospheres (Au@MSNs), which have a well-defined core–shell structure with ordered mesoporous silica as a shell. The resulting Au@MSNs have a high surface area (~521 m2/g) and uniform pore size (~2.5 nm) for the mesoporous silica shell. The diameter of the gold core can be regulated by adjusting the amount of HAuCl4. The catalytic performance of the Au@MSNs was investigated using the reduction of 4-nitrophenol as a model reaction. The mesopores of the silica shells provide direct access for the reactant molecules to diffuse and subsequently interact with the gold cores. In addition, the Au@MSNs display the great advantage of sintering-resistance to 950 ℃ because the mesoporous silica shells inhibit aggregation or deformation of the gold cores. The high thermal stability enables the Au@MSNs to be employed in high-temperature catalytic reactions.
Porous carbon nitride (CN) spheres with partially crystalline frameworks have been successfully synthesized via a nanocasting approach by using spherical mesoporous cellular silica foams (MCFs) as a hard template, and ethylenediamine and carbon tetrachloride as precursors. The resulting spherical CN materials have uniform diameters of ca. 4 μm, hierarchical three-dimensional (3-D) mesostructures with small and large mesopores with pore diameters centered at ca. 4.0 and 43 nm, respectively, a relatively high BET surface area of ~550 m2/g, and a pore volume of 0.90 cm3/g. High-resolution transmission electron microscope (HRTEM) images, wide-angle X-ray diffraction (XRD) patterns, and Raman spectra demonstrate that the porous CN material has a partly graphitized structure. In addition, elemental analyses, X-ray photoelectron spectra (XPS), Fourier transform infrared spectra (FT-IR), and CO2 temperature-programmed desorption (CO2-TPD) show that the material has a high nitrogen content (17.8 wt%) with nitrogen-containing groups and abundant basic sites. The hierarchical porous CN spheres have excellent CO2 capture properties with a capacity of 2.90 mmol/g at 25 ℃ and 0.97 mmol/g at 75 ℃, superior to those of the pure carbon materials with analogous mesostructures. This can be mainly attributed to the abundant nitrogen-containing basic groups, hierarchical mesostructure, relatively high BET surface area and stable framework. Furthermore, the presence of a large number of micropores and small mesopores also enhance the CO2 capture performance, owing to the capillary condensation effect.
We describe a nanocrystal self-assembly method for the preparation of rare earth fluoride nanotube (ReF-NT) arrays and magnetite-doped rare earth fluoride nanotubes (Fe3O4–ReF-NTs) by using porous anodic aluminum oxide (AAO) as a hard template. The ReF-NTs can be simply prepared by the impregnation of α-NaYF4 nanocrystals doped with Yb and Er into the channels of the porous AAO and show a highly ordered nanotube array and excellent upconversion (UC) fluorescence properties. Similarly, the Fe3O4–ReF-NTs are obtained by the self-assembly of a mixture of Fe3O4 and Yb/Er doped α-NaYF4 nanocrystals in the AAO pore channels and have a uniform dispersion of magnetite nanocrystals on the rare earth fluoride tube matrix and possess multifunctional magnetic/UC properties. The diameter of these nanotubes can be varied from 60 nm to several micrometers depending on the pore size of the AAO template. The wall thickness can be increased from 10 to 35 nm by increasing the concentration of nanocrystals from 0.02 to 0.4 mmol/L, while the morphology of the nanotubes can be varied from small isolated domain structures to percolating domains and eventually to compact domains. A template-directed formation mechanism is proposed and the quantitative predictions of the model for such self-assembled nanocrystal spreading processes are demonstrated. Strong UC fluorescent emissions are realized for the nanotube arrays and multifunctional nanotubes with UC excitation in the near-infrared (NIR) region. A strong magnetic response of the multifunctional nanotubes is observed, which facilitates their easy separation from solution by magnetic decantation using a permanent magnet.
A simple strategy for the synthesis of macro-mesoporous carbonaceous monolith materials has been demonstrated through an organic-organic self-assembly at the interface of an organic scaffold such as polyurethane (PU) foam. Hierarchically porous carbonaceous monoliths with cubic (Im