Abstract

No abstract

No abstract

Luminescent lanthanide downconversion nanoparticles (DCNPs) provide a combination of high luminescence intensity, sharp emission peaks with narrow bandwidth and a large Stokes' shift, leading to high‐performance biomedical applications mainly for imaging. The purpose of this study is to present a nanotoxicological study of DCNPs Y2O3 codoped with Eu3+ and functionalized with folic acid (FA). These assessments include cytotoxicity, genotoxicity, hemocompatibility, and in vitro inflammatory studies. We demonstrated by flow cytometry and confocal microscope the internalization of FA‐DCNPs in breast cancer and melanoma cells. They were synthesized by sol–gel method and coated with a thin silica shell to make them biocompatible; also they were functionalized with amino groups and FA ligands that bind to the folate receptors (FR) located on the surface of the cancer cells studied. This functionalization enables the DCNPs to be internalized into the cancer cells via endocytosis by the conjugation FA‐FR. The DCNPs were characterized with transmission electron microscope, Fourier transform infrared spectroscopy and photoluminescence. The nanotoxicological assessments demonstrated that both nanoparticles (bare and functionalized) are no cytotoxic and no genotoxic at the tested concentrations (0.01–20 μg/mL) in three cell lines (breast, skin cancer, and osteoblasts). Also they are hemocompatible and do not exert nitric oxide production in vitro by macrophages. The FA‐DCNPs were clearly localized into the cell cytoplasm with bright red luminescence. Thus, herein we present a complete nanotoxicological study of FA‐DCNPs Y2O3 codoped with Eu3+ and we conclude that these nanoparticles are biocompatible and can be further used for cancer cells bioimaging.

No abstract

No abstract

A thermoset polymer can be used for specific applications by creating a unique chemical composition that is designed for certain characteristic environments. To know the behavior of a thermoset polymer, it is necessary to thermally analyze its behavior during the curing process, as well as its mechanical behavior under certain loads that are applied in its field of application. In this study, the epoxy resin X was created at high temperatures, which there was no record of its thermal or mechanical behavior; the resin was analyzed to determine if it was possible to make a reduction in its curing cycle that was at temperature of 425° F with a time of 24 hours. As a result, through thermal analysis such as Differential Scanning Calorimetry (DSC), rheometry, Thermogravimetric Analysis (TGA) and Dynamic Mechanical Thermal Analysis (DMTA); as well as mechanical analysis, such as stress, hardness and planar cutting tests; it was possible to reduce the curing cycle of resin X, which is used in aerospace generators, from 24 hours at 425 ° F to 8 hours at 425 ° F. In the same way, this reduction of the cure cycle was verified by means of a qualification of a product that involved the reduction of the curing cycle of the epoxy resin obtaining very similar results to the original ones, verifying that the change of curing in the epoxy resin did not affected the functioning of the component. This methodology can be used and applied for the study of thermoset polymers that are used in several industries such as aerospace, automotive, among others.

The upconversion nanoparticles (UCNPs) possess the ability to absorb near infrared energy (980 nm) and upconvert it to emit in the visible spectra. In this research, the UNCPs emit in red (660 nm) due to the electronic transitions between two rare earth ions: Er3+ and Yb3+, this process is called energy transfer upconversion (ETU). The UCNPs were functionalized with aminosilanes and folic acid receptors (UCNP-FR) and analyzed by transmission electron microscopy, Fourier transform infrared spectroscopy and luminescence measurements. UCNPs-FR of Y2O3 have a particle size of 70 ± 10 nm and the Gd2O3 have a 50 ± 10 nm particle size. Both showed a good luminescence spectrum in comparison with the bare ones. Cytotoxicity of different amounts between 0.001 µg/ml to 1 µg/ml of bare and functionalized UCNPs was measured with the colorimetric assay MTT in three cancer cell lines: human cervical adenocarcinoma (HeLa), human breast cancer cells MB-MDA-231. Some concentrations of bare UCNPs were cytotoxic for cancer cells; however after their functionalization they resulted to be non-cytotoxic. The functionalized UCNPs were able to bind to folate receptors which are overexpressed in cervical and breast cancers cells. It was demonstrated by confocal microscopy, that the functionalized UCNPs were internalized into the cancer cells, confirming that they can be used as biolabels for breast and cervical cancer cells.