Synthesis of stable carboxy-terminated NaYF₄: Yb³⁺, Er³⁺@SiO₂nanoparticles with ultrathin shell for biolabeling applications

Abstract

Here, a two-step method has been developed for synthesizing carboxy-terminated NaYF(4): Yb(3+), Er(3+)@SiO(2) core@shell nanoparticles (UCNP@SiO(2)) with ultrathin shell (1.5 nm). First, the NaYF(4): Yb(3+), Er(3+) upconverting nanoparticles (UCNPs) were prepared using solvothermal technology; then, silica shells (SiO(2)) were deposited on the nanocrystals to form core-shell structures by the hydrolysis of tetraethylorthosilicate (TEOS). The ultrathin SiO(2) shell was obtained by increasing surfactant amount and decreasing TEOS amount in the reaction mixture. Carboxyethylsilanetriol (CTES) was used to generate the carboxy group on the particle surface. The carboxy-terminated UCNP@SiO(2) are ideally suited for biolabeling and bioimaging applications because the as-prepared nanoparticles have extreme colloidal and optical stabilities, and the carboxy groups on the particle surface easily react with amino residues of biomolecules. As an example, we reported on the interactions of Ricinus Communis Agglutinin (RCA 120) conjugated UCNP@SiO(2) with HeLa cells. The excellent performance of the RCA 120 conjugated UCNP@SiO(2) in cellular fluorescence imaging was demonstrated.

Imaging agents based on lanthanide doped nanoparticles

“…The absolute QY of the Nd 3+ emission in the 850-1400 nm range for the GdF 3 :Nd 3+ powders resulted to be 10.2 AE 1.6% upon an excitation wavelength of 800 nm and an excitation power density of 12 W cm À2 . To take profit of all these features for in vivo imaging, but having an additional signal in the visible region for in vitro experiments, Li et al 108,109 prepared NaGdF 4 based multishell dual mode (UC and DS) NPs. The functionalized NPs form stable colloids and their cellular uptake has been tested on Fig.…”

Monodisperse Water-Stable Sio2- Coated Fluoride Upconversion Nanoparticles with Tunable Shell Thickness

“…To address this problem, we coated these UCNPs with a shell layer of silica that makes the core-shell water soluble. The silica coating strategy had a number of advantages for bioapplications: (i) the multivalency of an extensively polymerized polysilane ensures that these UCNPs stay soluble, providing a spatial isolation of UCNPs from the performance-degrading substances in the environment; (ii) the silica was known to be biocompatible, chemically inert and optically transparent at visible and near infrared wavelengths [28], (iii) the chemistry of silica was well investigated, which could incorporate different functional groups (-COOH, -NH 2 , and -SH) to control the interactions with biological environments. Moreover, the ability to control the shell thickness was of particular importance to probe the 2e).…”

“…Several approaches has been attempted toward this regard, including SiO 2 coating, wrapping by small molecular surfactant, amphiphilic polymer, oxidizing oleic acid ligands with the Lemieuxvon Rudolf reagent, and ligand exchange [11,[15][16][17][18][19][20][21][22][23][24][25]. In particular, SiO 2 -coating are of particular interest, due to its high biocompatibility, easy surface modifi cation through silicon-enriched chemistry, and easy control of interparticle interactions [26][27][28][29]. However, there lacks a facile way to perform silica coating of UCNPs with a controlled thickness.…”

Highly efficient up-conversion luminescence in Er3+/Yb3+ co-doped Na5Lu9F32 single crystals by vertical Bridgman method

“…Considerable interests in rare-earth (RE) doped UC phosphors have burgeoned since the development of synthetic methods for creating highly processable UC materials with applications in biolabeling 1, 2 , sub-band gap energy harvesting in photovoltaics 3, 4 , and security printing 5 . Due to its potential applications in biological fluorescence and volumetric displays, much effort has been devoted to the investigation on UC in RE 3+ doped materials over the past years.…”