Understanding the cellular internalization mechanism of nanoparticles is essential to study their biological fate. Especially, due to the anisotropic properties, rod-like nanoparticles have attracted ...growing interest for the enhanced internalization efficiency with respect to spherical nanoparticles. Here, to elucidate the effect of aspect ratio of rod-like nanoparticles on cellular uptake, tobacco mosaic virus (TMV), a typical rod-like bionanoparticle, is developed as a model. Nanorods with different aspect ratios can be obtained by ultrasound treatment and sucrose density gradient centrifugation. By incubating with epithelial and endothelial cells, we found that the rod-like bionanoparticles with various aspect ratios had different internalization pathways in different cell lines: microtubules transport in HeLa and clathrin-mediated uptake in HUVEC for TMV4 and TMV8; caveolae-mediated pathway and microtubules transport in HeLa and HUVEC for TMV17. Differently from most nanoparticles, for all the three TMV nano-rods with different aspect ratios, macropinocytosis takes no effect on the internalization in both cell types. This work provides a fundamental understanding of the influence of aspect ratio on cellular uptake decoupled from charge and material composition.
Oxygen evolution reaction (OER) is an important bottleneck for large-scale acidic water splitting applications due to its sluggish reaction kinetics. Therefore, the development of highly active, ...stable, and inexpensive electrocatalysts for OER remains a challenge. Herein, we develop the iridium doped Co3O4 (Ir–Co3O4) with low Ir content of 2.88 wt% for efficient acidic OER. Considering systemic characterizations, it is probably concluded that Ir can be uniformly doped into the lattice of Co3O4 and induce a certain distortion. The electrochemical results reveal that Ir–Co3O4 nanoparticles demonstrate significantly enhanced electrocatalytic OER activity and stability in 0.5 M H2SO4 solution compared with pure Co3O4, in which the overpotential at the current density of 10 mA cm−2 decreases from 382 mV to 225 mV and the value of Tafel slope decreases from 101.7 mV dec−1 to 64.1 mV dec−1. Besides, Ir–Co3O4 exhibits excellent electrocatalytic durability for continuous 130 h's test without any activity attenuation. Moreover, this work provides a kind of high-performance acidic OER electrocatalyst for the development of hydrogen energy.
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•Ir doped Co3O4 nanoparticles are successfully synthesized by hydrothermal method.•Ir doping effectively regulates the electronic structure of Co3O4.•Ir–Co3O4 nanoparticles exhibit excellent acidic oxygen evolution performance.
Spinel oxides have attracted widespread interest for electrocatalytic applications owing to their unique crystal structure and properties. The surface structure of spinel oxides significantly ...influences the electrocatalytic performance of spinel oxides. Herein, we report a Li reduction strategy that can quickly tune the surface structure of CoFe
O
(CFO) nanoparticles and optimize its electrocatalytic oxygen evolution reaction (OER) performance. Results show that a large number of defective domains have been successfully introduced at the surface of CFO nanopowders after Li reduction treatment. The defective CFO nanoparticles demonstrate significantly improved electrocatalytic OER activity. The OER potential observed a negative shift from 1.605 to 1.513 V at 10 mA cm
, whereas the Tafel slope is greatly decreased to 42.1 mV dec
after 4 wt % Li reduction treatment. This efficient Li reduction strategy can also be applied to engineer the surface defect structure of other material systems and broaden their applications.
Spinel oxides have attracted widespread interest for electrocatalytic applications owing to their unique crystal structure and properties. The surface structure of spinel oxides significantly ...influences the electrocatalytic performance of spinel oxides. Herein, we report a Li reduction strategy that can quickly tune the surface structure of CoFe2O4 (CFO) nanoparticles and optimize its electrocatalytic oxygen evolution reaction (OER) performance. Results show that a large number of defective domains have been successfully introduced at the surface of CFO nanopowders after Li reduction treatment. The defective CFO nanoparticles demonstrate significantly improved electrocatalytic OER activity. The OER potential observed a negative shift from 1.605 to 1.513 V at 10 mA cm–2, whereas the Tafel slope is greatly decreased to 42.1 mV dec–1 after 4 wt % Li reduction treatment. This efficient Li reduction strategy can also be applied to engineer the surface defect structure of other material systems and broaden their applications.
Mercury is an extremely toxic chemical pollutant of our environment. It has attracted the world's attention due to its high mobility and the ease with which it accumulates in organisms. Sensitive ...devices and methods specific for detecting mercury ions are, hence, in great need. Here, we have integrated a DNA strand displacement reaction with a whispering gallery mode (WGM) sensor for demonstrating the detection of Hg(2+) ions. Our approach relies on the displacement of a DNA hairpin structure, which forms after the binding of mercury ions to an aptamer DNA sequence. The strand displacement reaction of the DNA aptamer provides highly specific and quantitative means for determining the mercury ion concentration on a label-free WGM sensor platform. Our approach also shows the possibility for manipulating the kinetics of a strand displacement reaction with specific ionic species.
Molybdenum silicides are promising electrocatalysts for hydrogen evolution in acidic environment due to their dual characteristics of metal and ceramics as well as high electrical conductivity and ...acid resistance. At present, most of the transition metal silicides were synthesized at high temperature, resulting in large particle size and small specific surface area, which seriously limits their electrocatalytic applications. Herein, we report a low temperature strategy for the synthesis of ultrafine Mo5Si3 and MoSi2 nanoparticles with diameter of ∼5 nm by molten salt method. Results show that both of them demonstrated excellent electrocatalytic hydrogen evolution activity and stability in 0.5 M H2SO4 solution, in which the overpotentials of Mo5Si3 and MoSi2 nanoparticles at 10 mA cm−2 are 80 mV and 94 mV, respectively. This general strategy may light up the preparation of ultrafine transition metal silicides nanoparticles and facilitate their applications in electrocatalytic areas.
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•Ultrafine Mo5Si3 and MoSi2 nanoparticles with diameter of ∼5 nm were synthesized by molten salt reduction method.•The nanoparticles demonstrate large specific surface area and fully exposed electrocatalytic active sites.•Mo5Si3 show electrocatalytic HER activity in 0.5 M H2SO4 with potential of −80 mV (η10) and Tafel slope of 65.1 mV dec−1.•MoSi2 show electrocatalytic HER activity in 0.5 M H2SO4 with potential of −94 mV (η10) and Tafel slope of 71.2 mV dec−1.•Mo5Si3 and MoSi2 reveal outstanding electrochemical stability for 6000 cycles of CV and 15 h of chronopotentiometry test.
Due to the nano-confinement effect, grafting green fluorescent protein-like chromophores on the interior surface of tobacco mosaic virus can greatly enhance its fluorescence emission in various ...solvents.
The current work reports an intriguing discovery of how the force exerted on protein complexes like filamentous viruses by the strong interchain repulsion of polymer brushes can induce subtle changes ...of the constituent subunits at the molecular scale. Such changes transform into the macroscopic rearrangement of the chiral ordering of the rodlike virus in three dimensions. For this, a straightforward "grafting-to" PEGylation method has been developed to densely graft a filamentous virus with poly(ethylene glycol) (PEG). The grafting density is so high that PEG is in the polymer brush regime, resulting in straight and thick rodlike particles with a thin viral backbone. Scission of the densely PEGylated viruses into fragments was observed due to the steric repulsion of the PEG brush, as facilitated by adsorption onto a mica surface. The high grafting density of PEG endows the virus with an isotropic-nematic (I-N) liquid crystal (LC) phase transition that is independent of the ionic strength and the densely PEGylated viruses enter into the nematic LC phase at much lower virus concentrations. Most importantly, while the intact virus and the one grafted with PEG of low grafting density can form a chiral nematic LC phase, the densely PEGylated viruses only form a pure nematic LC phase. This can be traced back to the secondary to tertiary structural change of the major coat protein of the virus, driven by the steric repulsion of the PEG brush. Quantitative parameters characterising the conformation of the grafted PEG derived from the grafting density or the I-N LC transition are elegantly consistent with the theoretical prediction.
It has become a challenge to further enhance the electrocatalytic performance of perovskite oxides due to their limited active surface area. Herein, we propose a top-down strategy for the ...amorphization of crystalline LaCoO3 nanopowders with significantly enhanced specific surface area and electrocatalytic oxygen evolution reaction (OER) activity and durability, in which the overpotential at the current density of 10 mA cm–2 reduced from 405 to 293 mV, and the Tafel slope decreased from 96.6 to 63.4 mV dec–1. This work provides an effective method for the property optimization of nanometer perovskite oxides and the design of high-performance electrocatalysts.
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