Initial Biological Assessment of Upconversion Nanohybrids

Abstract

Nanoparticles for medical use should be non-cytotoxic and free of bacterial contamination. Upconversion nanoparticles (UCNPs) coated with cucurbit[7]uril (CB[7]) made by combining UCNPs free of oleic acid, here termed bare UCNPs (UCn), and CB[7], i.e., UC@CB[7] nanohybrids, could be used as photoactive inorganic-organic hybrid scaffolds for biological applications. UCNPs, in general, are not considered to be highly toxic materials, but the release of fluorides and lanthanides upon their dissolution may cause cytotoxicity. To identify potential adverse effects of the nanoparticles, dehydrogenase activity of endothelial cells, exposed to various concentrations of the UCNPs, was determined. Data were verified by measuring lactate dehydrogenase release as the indicator of loss of plasma membrane integrity, which indicates necrotic cell death. This assay, in combination with calcein AM/Ethidium homodimer-1 staining, identified induction of apoptosis as main mode of cell death for both particles. The data showed that the UCNPs are not cytotoxic to endothelial cells, and the samples did not contain endotoxin contamination. Higher cytotoxicity, however, was seen in HeLa and RAW 264.7 cells. This may be explained by differences in lysosome content and particle uptake rate. Internalization of UCn and UC@CB[7] nanohybrids by cells was demonstrated by NIR laser scanning microscopy.

Functional Micro-/Nanostructures in Agrofood Science: Precise Inspection, Hazard Elimination, and Potential Health Risks

“…Qi et al observed the cell morphology by transmission electron microscopy (TEM), and the results indicated that MNPs exhibited the ability to promote the expression of Bax, which is a programmed cell death acceleration protein, and induced greater cell necrosis as well. Moreover, UCNPs are not considered toxic materials in general, and the release of fluorides and lanthanides during the dissolution process of UCNPs may introduce cytotoxicity …”

“…Moreover, UCNPs are not considered toxic materials in general, and the release of fluorides and lanthanides during the dissolution process of UCNPs may introduce cytotoxicity. 135 Metal nanoparticles, especially precious metal nanoparticles such as gold and silver, are a commonly used nanomaterials in the food and medical fields. However, in recent years, research studies have focused on AuNPs exposure in a skin penetration route.…”

Up‐ and Down‐Shifting Nanomaterials with Chiroptical Responses: Origin of their Chiroptical Activity and Applications

“…[80] UCNPs display exceptional optical properties, such as multiple and narrow emission bands, non-photobleaching, nonphotoblinking, long luminescence lifetimes, high stability and low cytotoxicity. [81][82][83] Especially, the use of NIR excitation light has attracted the attention of researchers during the last decade due to its high penetration depth in tissues, as well as low background autofluorescence in biosamples. [84] Hence, UCNPs have been used for different widespread applications such as in bioimaging, phototherapy or biosensing, but also in anticounterfeiting, solar cells, or photocatalysis.…”

Bioimaging with Upconversion Nanoparticles

“…The cytotoxic effect of UCNPs has been found to vary based on surface coating: bare UCNPs resulted in elevated cytotoxicity when compared with silica‐ or cucurbit[7]uril‐ coated UCNPs, and cell line: HeLa and RAW 264.7 cells exhibited elevated cytotoxicity whereas EAhy 926 endothelial cells did not. [ 179 ] Additionally, neither 980 nm nor 808 nm lasers with power densities of 2.5 W cm −2 for as long as 20 min caused a notable reduction in HeLa cell viability. However, at these levels, a nonsignificant downward trend between the controls, 10, and 20 min time points may point to reaching an upper threshold of laser power for this experiment.…”