Ultrasmall lanthanide-doped nanoparticles as multimodal platforms

Abstract

Recently, there has been a great amount of interest in nanoparticles which are able to provide a platform with high contrast for multiple imaging modalities in order to advance the tools available to biomedical researchers and physicians. However, many nanoparticles do not have ideal properties to provide high contrast in different imaging modes. In order to address this, ultrasmall lanthanide doped oxide and fluoride nanoparticles with strong NIR to NIR upconversion fluorescence and a strong magnetic response for magnetic resonance imaging (MRI) have been developed. Specifically, these nanoparticles incorporate gadolinium, dysprosium, or a combination of both into the nano-crystalline host to achieve the magnetic properties. Thulium, erbium, and neodymium codopants provide the strong NIR absorption and emission lines that allow for deeper tissue imaging since near infrared light is not strongly absorbed or scattered by most tissues within this region. This also leads to better image quality and lower necessary excitation intensities. As a part of the one pot synthesis, these nanoparticles are coated with peg, pmao, or d-glucuronic acid to make them water soluble, biocompatible, and bioconjugable due to the available carboxyl or amine groups. Here, the synthesis, morphological characterization, magnetic response, NIR emission, and the quantum yield will be discussed. Cytotoxicity tested through cell viability at varying concentrations of nanoparticles in growth media will also be discussed.

Labeling of HeLa cells using ZrO 2 : Yb 3 + - Er 3 + nanoparticles with upconversion emission

“…1,2 There are several potential benefits for the use of nanocrystals with UPC emission in biological applications, such as no damage of tissues; anti-Stokes emission; long lifetimes; photostability; increased contrast in biological specimens due to the absence of autofluorescence upon excitation with IR light; and simultaneous detection of multiple targeted analytes. [3][4][5][6] Other advantages of the UPC emission are the reduction of photobleaching and scattering in tissues, which avoid the use of complicated and high-cost femtosecond lasers and photomultiplier tubes. [7][8][9][10] For biomedical applications, such as cancer detection, biolabeling, and bioimaging, luminescent nanoparticles preferably have to form a stable colloidal solution under physiological conditions.…”