Vapor phase mediated cellular uptake of sub 5 nm nanoparticles

Nanoparticles became an important and wide-used tool for cell imaging because of their unique optical properties. Although the potential of nanoparticles (NPs) in biology is promising, a number of questions concerning the safety of nanomaterials and the risk/benefit ratio of their usage are open. Here, we have shown that nanoparticles produced from silicon carbide (NPs) dispersed in colloidal suspensions are able to penetrate into surrounding air environment during the natural evaporation of the colloids and label biological cells via vapor phase. Natural gradual size-tuning of NPs in dependence to the distance from the NP liquid source allows progressive shift of the fluorescence color of labeled cells in the blue region according to the increase of the distance from the NP suspension. This effect may be used for the soft vapor labeling of biological cells with the possibility of controlling the color of fluorescence. However, scientists dealing with the colloidal NPs have to seriously consider such a NP's natural transfer in order to protect their own health as well as to avoid any contamination of the control samples

Poly-lactic acid nanoparticles (PLA-NP) promote physiological modifications in lung epithelial cells and are internalized by clathrin-coated pits and lipid rafts

BackgroundPoly-lactic acid nanoparticles (PLA-NP) are a type of polymeric NP, frequently used as nanomedicines, which have advantages over metallic NP such as the ability to maintain therapeutic drug levels for sustained periods of time. Despite PLA-NP being considered biocompatible, data concerning alterations in cellular physiology are scarce.MethodsWe conducted an extensive evaluation of PLA-NP biocompatibility in human lung epithelial A549 cells using high throughput screening and more complex methodologies. These included measurements of cytotoxicity, cell viability, immunomodulatory potential, and effects upon the cells’ proteome. We used non- and green-fluorescent PLA-NP with 63 and 66 nm diameters, respectively. Cells were exposed with concentrations of 2, 20, 100 and 200 µg/mL, for 24, 48 and 72 h, in most experiments. Moreover, possible endocytic mechanisms of internalization of PLA-NP were investigated, such as those involving caveolae, lipid rafts, macropinocytosis and clathrin-coated pits.ResultsCell viability and proliferation were not altered in response to PLA-NP. Multiplex analysis of secreted mediators revealed a low-level reduction of IL-12p70 and vascular epidermal growth factor (VEGF) in response to PLA-NP, while all other mediators assessed were unaffected. However, changes to the cells’ proteome were observed in response to PLA-NP, and, additionally, the cellular stress marker miR155 was found to reduce. In dual exposures of staurosporine (STS) with PLA-NP, PLA-NP enhanced susceptibility to STS-induced cell death. Finally, PLA-NP were rapidly internalized in association with clathrin-coated pits, and, to a lesser extent, with lipid rafts.ConclusionsThese data demonstrate that PLA-NP are internalized and, in general, tolerated by A549 cells, with no cytotoxicity and no secretion of pro-inflammatory mediators. However, PLA-NP exposure may induce modification of biological functions of A549 cells, which should be considered when designing drug delivery systems. Moreover, the pathways of PLA-NP internalization we detected could contribute to the improvement of selective uptake strategies

Impact of irradiation on the microstructure of nanocrystalline materials

Nanostructured materials should present a good resistance to irradiation because the large volume fraction of grain boundaries can be an important sink for radiation-induced defects. The objective of the present study is to experimentally investigate the irradiation impact on the microstructure in nanostructured materials. Nickel and Cu-0.5A(2)O(3) specimens were synthesized by electro deposition (ED) and severe plastic deformation (SPD). 590 MeV proton irradiation was conducted in the Proton IRradiation EXperiment facility (PIREX). ED Ni were also irradiated in Tandem type accelerator with Ni+ ions of 840 keV. The irradiation induced microstructure, which leads to hardening, consists exclusively of stacking fault tetrahedra. Their density appears much lower than in the case of coarser grained material. In order to assess the change in grain size induced by irradiation, annealing experiments have been performed. These results, experimentally showing the resistance of nanostructured material to radiation damage, are presented here. (C) 2004 Elsevier B.V. All rights reserved

Irradiation-induced stacking fault tetrahedra in fcc metals

Irradiation induces the formation of stacking fault tetrahedra (SFTs) in a number of fcc metals, such as stainless steel and pure copper. In order to understand the role of the material's parameters on this formation, pure Cu, Ni, Pd and Al, having a respective stacking fault energy of 45, 125, 180 and 166 mJ m(-2), have been irradiated with high energy protons to a dose of about 10(-2) dpa at room temperature. The irradiation-induced microstructure has been investigated using transmission electron microscopy. All irradiated metals but Al present SFTs. The proportion of perfect, truncated and grouped SFTs has been determined. The SFT energy as a function of size has been calculated using elasticity of the continuum, with respect to the energy of a number of other possible defect configurations. It appears that the key parameters are the stacking fault energy and the shear modulus. Their implication on the formation and stability of the SFTs is discussed

Structure-mechanics relationships in proton irradiated pure titanium

Radiation effects on the mechanical behavior and the microstructure of pure her, titanium polycrystals have been investigated. Results have been analyzed in the frame of a dispersed obstacle hardening model and compared to those previously obtained for pure metals with a fcc or bee structure. such as Cu and I'd or Fe. respectively. Differences in the defect accumulation rate and the dose dependence of hardening are discussed in terms of possible irradiation hardening mechanisms for the hcp structure. (C) 2002 Elsevier Science B.V. All rights reserved

Temperature dependence of irradiation effects in pure titanium

The microstructural modifications due to irradiation in hcp pure metals and their consequences on the mechanical properties have been investigated. Experimental results for proton-irradiated pure polycrystalline titanium are presented and discussed. Samples have been irradiated with 590 MeV protons to a low dose range at two different temperatures, room temperature and 523 K. Defect sizes and densities as a function of dose have been determined by means of transmission electron microscopy observations, and hardening has been measured from uniaxial tensile stress-strain curves. The dose dependence of the irradiation hardening has been found to depend strongly on the investigated temperatures. These results are discussed in terms of the main deformation mechanism operating at each temperature

Effects of irradiation on the microstructure and mechanical properties of nanostructured materials

Nanostructured materials should present a good resistance to irradiation because the large volume fraction of grain boundaries can be an important sink for radiation-induced defects. The objective of the present study is to experimentally investigate the irradiation impact on the microstructure and mechanical properties in nanostructured materials. Nickel and Cu-0.5Al(2)O(3) specimens were synthesized by electro deposition (ED) and severe plastic deformation (SPD). Mean grain size of the unirradiated specimen is about 30 nm for the ED Ni and about 115 nm for the SPD Ni. 590 MeV proton irradiation and 840 keV nickel ion irradiation were conducted at room temperature. Vickers hardness measurements and transmission electron microscope observation were performed to examine the impact of irradiation on nanocrystalline materials. It appears that the irradiation induced microstructure in Ni and in Cu-0.5Al(2)O(3), which leads to hardening, consists exclusively of stacking fault tetrahedra. Their density appears much lower than in the case of coarser grained material. These results, experimentally showing the resistance of nanostructured material to radiation damage, are presented here