Search results for "Upconversion nanoparticles"

Upconversion nanoparticles with a strong acid-resistant capping

2016

Water-dispersible upconversion nanoparticles (β-NaYF:Yb,Er, UCNP) coated with a thin shell of a biocompatible copolymer comprising 2-hydroxyethylmethacrylate (HEMA) and 2-acrylamido-2-methyl-1-propanesulphonsulphonic acid (AMPS), which we will term COP, have been prepared by multidentate grafting. This capping is remarkably resistant to strong acidic conditions as low as pH 2. The additional functionality of the smart UCNP@COP nanosystem has been proved by its association to a well-known photosensitizer (namely, methylene blue, MB). The green-to-red emission ratio of the UC@COP@MB nanohybrid exhibits excellent linear dependence in the 7 to 2 pH range as a consequence of the release of the d…

Polysulfonate Cappings on Upconversion Nanoparticles Prevent Their Disintegration in Water and Provide Superior Stability in a Highly Acidic Medium

2018

The stability of organic cappings on hexagonal NaYF4:Ln3+ upconversion nanoparticles (UCNPs) is crucial for their luminescence efficiency in aqueous solutions. The capping removal quickens as the acidity of the medium increases. We demonstrate here that polysulfonates, namely poly(2-acrylamido-2-methyl-1-propanesulfonate) (PAMPS) and poly(sodium 4-styrene sulfonate) (PSS), remain anchored to the surface of NaYF4:Yb3+,Er3+/Tm3 UCNPs even at a pH as low as 2 due to strong acidity of the sulfonate anchoring groups (pKa of ca. −3). Bare UCNPs progressively disintegrate into their compositional F–, Na+, Y3+, and Ln3+ ions. Their disintegration is particularly worrying in highly diluted dispersio…

Upconversion Nanoparticles for Bioimaging and Regenerative Medicine.

2016

Nanomaterials are proving useful for regenerative medicine in combination with stem cell therapy. Nanoparticles can be administrated and targeted to desired tissues or organs and subsequently, be used in non-invasive real-time visualization and tracking of cells by means of different imaging techniques, they can act as therapeutic agent nanocarriers, and can also serve as scaffolds to guide the growth of new tissue. Nanoparticles can be of different chemical nature, such as gold, iron oxide, cadmium selenide, and carbon, and have the potential to be used in regenerative medicine. However, there are still many issues to be solved, such as toxicity, stability, and resident time. Upconversion …

Breaking the Nd3+-sensitized upconversion nanoparticles myth about the need of onion-layered structures

2018

Up to now, most strategies to build efficient 800 nm-light responsive upconversion nanoparticles (UCNPs) have included onion-layered structures, in which Nd3+ is confined within the inorganic crystal structure of at least one layer. We report here an easy room-temperature modular preparation of core-shell UCNPs consisting of NaYF4:Yb,Er(Tm)/NaYF4 (UCCS) with Nd3+ anchored at the organic capping by using cucurbituril[7] (CB[7]) as an adhesive. Strikingly, excitation at 800 nm effectively triggers the upconversion emission of UCCS@CB[7]@Nd nanohybrids.

Lengthening the Lifetime of Common Emissive Probes to Microseconds by a Jigsaw‐Like Construction of NIR‐Responsive Nanohybrids

2020

Initial Biological Assessment of Upconversion Nanohybrids

2021

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. Da…

Functional Nanohybrids Based on Dyes and Upconversion Nanoparticles

2020

Upconversion nanoparticles (UCNPs) and dyes are combined to make nanohybrid systems, which take advantage of the synergic relationship between lanthanide (Ln)-based UCNPs and dyes. Ln-UCNPs are inorganic nanophosphors which absorb NIR light and emit narrow emission bands in the UV-NIR region with long luminescence lifetimes. These unique properties, when coordinated properly with dyes of the appropriate photophysical features, produce nanosystems with new photophysical properties. In this context, the UCNP-dye nanohybrids are very promising for potential sensing (ions and biomolecules) and theragnosis (imaging and therapy, e.g. photodynamic therapy).

Cucurbit[n]uril-capped upconversion nanoparticles as highly emissive scaffolds for energy acceptors.

2015

Spontaneous adsorption of cucurbit[n]uril CB[n] (n = 6, 7, and 8) on the surface of naked upconversion nanoparticles (UCNPs), in particular, NaYF4:Er3+(2%),Yb3+(18%) gave rise to UCNP@CB[n] exclusion complexes. These complexes proved to be highly stable as well as highly emissive under near-infrared excitation. By using two tricyclic basic dyes (specifically, methylene blue and pyronin Y) as a proof of concept, we demonstrate that the UCNP@CB[n] (n = 6, 7) nanohybrids can form exclusion complexes with this type of dyes via the CB carbonyl free portal, i.e., UCNP@CB@dye hybrids, thus making it possible to locate a high concentration of the dyes close to the UCNP and, consequently, leading to…