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排序方式: 共有113条查询结果,搜索用时 15 毫秒
1.
Qing Zhang Sinan Deng Jinlin Liu Xiaoxia Zhong Jie He Xianfeng Chen Bowen Feng Yanfei Chen Kostya Ostrikov 《Advanced functional materials》2019,29(5)
Folic acid, due to its high affinity toward folate receptors (FR), is recognized as one of the most promising cancer targeting vectors. However, the inherent defects of low water solubility (1.6 µg mL?1), high sensitivity toward photo‐bleaching, low fluorescent quantum yields (QYs, <0.5%) seriously limit its practical application. Herein, ultrastable, highly luminescent graphene quantum dots (GQDs) that selectively target diverse cancer cells are prepared and tested. The new GQDs present step changes compared to common folic acid through an ≈6250 times increase in water solubility (to ≈10 mg mL?1), more than 150 times in QYs (up to ≈77%), while maintaining luminescence stability up to 98% when subjected to UV, visible light, and heating over 360 min. It is shown that the suppression of nonradiative transitions by amino groups pyrolyzed from pterin plays a key role in the mechanism of high QYs and excellent stability. The functional groups that are likely responsible for the selective targeting of cancer cells with different levels of folate receptor expression on the surface are identified. Collectively with these promising properties, the new functional graphene quantum dots may open a new avenue for cancer diagnosis, drug delivery, and therapies. 相似文献
2.
The possibility for the switch-over of the growth mode from a continuous network to unidirectional arrays of well-separated, self-organized, vertically oriented graphene nanosheets has been demonstrated using a unique, yet simple plasma-based approach. The process enables highly reproducible, catalyst-free synthesis of arrays of graphene nanosheets with reactive open graphitic edges facing upwards. Effective control over the nanosheet length, number density, and the degree of alignment along the electric field direction is achieved by a simple variation of the substrate bias. These results are of interest for environment-friendly fabrication of next-generation nanodevices based on three-dimensional, ordered self-organized nanoarrays of active nanostructures with very large surface areas and aspect ratios, highly reactive edges, and controlled density on the substrate. Our simple and versatile plasma-based approach paves the way for direct integration of such nanoarrays directly into the Si-based nanodevice platform. 相似文献
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Ag nanoparticles and Fe-coated Si micrograins were separately deposited onto Si(1 0 0) surfaces and then exposed to an Ar + CH4 microplasma at atmospheric pressure. For the Ag nanoparticles, self-organized carbon nanowires, up to 400 nm in length were produced, whereas for the Fe-coated Si micrograins carbon connections with the length up to 100 μm were synthesized on the plasma-exposed surface area of about 0.5 mm2. The experiment has revealed that long carbon connections and short nanowires demonstrate quite similar behavior and structure. While most connections/nanowires tended to link the nearest particles, some wires were found to ‘dissolve’ into the substrate without terminating at the second particle. Both connections and nanowires are mostly linear, but long carbon connections can form kinks which were not observed in the carbon nanowire networks. A growth scenario explaining the carbon structure nucleation and growth is proposed. Multiscale numerical simulations reveal that the electric field pattern around the growing connections/nanowires strongly affects the surface diffusion of carbon adatoms, the main driving force for the observed self-organization in the system. The results suggest that the microplasma-generated surface charges can be used as effective controls for the self-organized formation of complex carbon-based nano-networks for integrated nanodevices. 相似文献
8.
O. M. Ostrikov 《Technical Physics Letters》2000,26(11):958-959
Phase diffraction gratings can be created using the phenomenon of crystal twinning. Conditions of the grating formation and possibilities for increasing the quality of gratings are considered. 相似文献
9.
Petroleum-containing industrial wastes and petroleum products lost during processes (losses) are quantitatively and qualitatively
basic environmental pollutants-of water, soil, and air. Some petroleum wastes from production and use of lubricants (greases,
motor and industrial oils, etc.) are collected and regenerated. Wastes which are not regenerated due to their physicochemical
properties are dangerous environmental pollutants.
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Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 4, pp. 14–15, July–August, 2007. 相似文献
10.
Single‐walled carbon nanotubes are promising for many applications due to their unique mechanical, electrical and optical properties. However, their application has been hampered so far by the lack of controllability in the direct growth process, in particular the size and chirality distributions which inevitably lead to a large variability of their electronic structures. Here we demonstrate the effect of catalyst interfacial diffusion using a tri‐layered Al2O3/Fe(Mo)/Al2O3 catalyst and achieve the effective control of density, diameter, and conductivity of the as‐grown nanotube networks. This method modulates the thickness of the top Al2O3 layer which affects the diffusion of Fe atoms and subsequently the formation of catalyst nanoparticles. We show that the tri‐layered catalyst allows one to vary the density of networks from 0.18 to 35 tubes/μm2, the diameter from 1.36 to 1.72 nm, and the metallic fraction from 20% to 45%. It may thus represent a promising strategy for tailoring the properties of as‐grown carbon nanotube networks for their proposed applications. 相似文献