A facile synthesis of NaYF₄:Yb³⁺/Er³⁺nanoparticles with tunable multicolor upconversion luminescence properties for cell imaging

Abstract

The ability to manipulate the upconversion luminescence of lanthanide-ion doped fluoride upconversion nanoparticles (UCNPs) is critical and highly desired due to their wide applications in color displays, multiplexing bioassays and multicolor imaging. Here, we developed a facile strategy for simultaneously tuning color output and enhancing upconversion emission of Yb 3+ /Er 3+ doped fluoride UCNPs, based on adjusting the crystalline phases and particle size. With the transformation of crystalline phases from a, a transition state of a mixed b, and finally to b phase, the upconversion emission color output changed from red, yellow, and finally turned green. That is, the UCNPs' emission is sensitive to the crystallite size and phase. Moreover, the fluorescence intensity of the obtained UCNPs became stronger with the crystalline phase changing from a to b. Three kinds of UCNPs including a-UCNPs, a mixed b-UCNPs, and b-UCNPs were used for cell imaging, while the transition state phase a mixed b-UCNPs was the better candidate.

An overview of nanoparticles commonly used in fluorescent bioimaging

“…Coated with polyethyleneneimine, such particles were used to image cells. 153 Examples for applications include the kinetic determination of the activity of the enzyme phospholipase. 154 A mixture of a PEGylated phospholipid and a rhodamine-labeled phospholipid was deposited on an UCNP composed of hexagonal NaYF 4 doped with 20% Yb(III) and 2% Er(III).…”

Selective Detection of Hg2+ Ion Using Upconversion Luminescent Nanoparticles

“…The PL intensity increased with increasing reaction time, as shown in Figure . It is well known that the PL intensity from the hexagonal phase of NaLuGdF 4 is higher than that from the cubic phase . By increasing the reaction time, more hexagonal phases were formed from the cubic phase, resulting in the enhancement of the PL intensity.…”

“…The advantages of using lower energy as an excitation source include the low damage to analytes and the absence of photobleaching and autofluorescence interference. Luminescent inorganic nanoparticles doped with trivalent lanthanide (Ln 3+ ) ions have been widely employed in bioimaging, immunoassay, and analytical chemistry as the most efficient systems for visible UC photoluminescence (PL).…”

“…Mercury is a highly toxic environmental pollutant with bioaccumulative properties, so much effort has been devoted to developing new materials for simple and efficient sensing of the mercury ion. Recent progress in the synthesis of UC nanoparticles (UCNPs) has shown highly promising capabilities to work as new sensors . An “on–off” probe based on the composite silicate‐UCNPs for Hg 2+ detection has been reported .…”

The Effect of Hydrothermal Treatment on the Morphologies and Optical Properties of Upconversion NaYF4:Ln3+ Crystals

“…Normally, organic molecules such as oleic, citric and ethylenediamine acids, polyethyleneimine (PEI), poly(ethylene glycol) (PEG), or polyvinylpyrrolidone (PVP) have been explored as capping agents to control the morphologies and size of the crystals. [13][14][15] The crystals doped with lanthanide ions, when functionalized with biocompatible agents, become invisible Vol. 28, No.…”