Biofunctionalization of Fluorescent Rare‐Earth‐Doped Lanthanum Phosphate Colloidal Nanoparticles

We report here a facile method to obtain folic acid (FA)-protected gold nanoparticles (Au NPs) by heating an aqueous solution of HAuCl(4)/FA in which FA acts as both the reducing and stabilizing agent. The successful formation of FA-protected Au NPs is demonstrated by UV/Vis spectroscopy, transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The intracellular uptake of these nanoparticles is facilitated by HeLa cells overexpressing the folate reporter, which itself is significantly inhibited by free FA in a competitive assay as quantified by inductively coupled plasma mass spectroscopy (ICP-MS). This simple one-step approach affords a new perspective for creating functional nanomaterials, and the resulting biocompatible, functional Au NPs may find some prospective applications in various biomedical fields.

Section: Resultsmentioning

confidence: 99%

One‐Step Synthesis of Folic Acid Protected Gold Nanoparticles and Their Receptor‐Mediated Intracellular Uptake

Zhang

et al. 2009

“…[9] At present, there are only a select number of reports on the use of lanthanide-based nanoparticles as potential biolabels that emit in the visible region, by either upconversion or downconversion processes. [5] Examples include the bioconjugation of Ln 3 + -doped LaF 3 nanoparticles to avidin by our group, [10] and work done by Caruso and co-workers [11] with the functionalization of LaPO 4 :Ce/Tb nanoparticles with streptavidin for biotin-streptavidin binding studies. In addition, a recent contribution from Li and co-workers [12] demonstrates that an Er 3 + /Yb 3 + upconverting nanoparticle label can be used in fluorescence resonant energy transfer (FRET)-type analyses, whereby the emission of the upconverting nanoparticles is quenched by the energy-accepting gold nanoparticles that are functionalised with biotin for biotin-avidin detection and quantification.…”

Section: Introductionmentioning

confidence: 97%

Silica‐Coated Ln³⁺‐Doped LaF₃ Nanoparticles as Robust Down‐ and Upconverting Biolabels

Sivakumar

Diamente

Veggel

2006

314

222

The preparation of nearly monodisperse (40 nm), silica-coated LaF(3):Ln(3+) nanoparticles and their bioconjugation to FITC-avidin (FITC=fluorescein isothiocyanate) is described in this report. Doping of the LaF(3) core with selected luminescent Ln(3+) ions allows the particles to display a range of emission lines from the visible to the near-infrared region (lambda=450-1650 nm). First, the use of Tb(3+) and Eu(3+) ions resulted in green (lambda=541 nm) and red (lambda=591 and 612 nm) emissions, respectively, by energy downconversion processes. Second, the use of Nd(3+) gave emission lines at lambda=870, 1070 and 1350 nm and Er(3+) gave an emission line at lambda=1540 nm by energy downconversion processes. Additionally, the Er(3+) ions gave green and red emissions and Tm(3+) ions gave an emission at lambda=800 nm by upconversion processes when codoped with Yb(3+) (lambda(ex)=980 nm). Bioconjugation of avidin, which has a bound fluorophore (FITC) as the reporter, was carried out by means of surface modification of the silica particles with 3-aminopropyltrimethoxysilane, followed by reaction with the biotin-N-hydroxysuccinimide activated ester to form an amide bond, imparting biological activity to the particles. A 25-fold or better increase in the FITC signal relative to the non-biotinylated silica particles indicated that there is minimal nonspecific binding of FITC-avidin to the silica particles.

“…[11] These nanoparticles display multicolored emissions that have a high quantum yield and have potential applications as biosensors. [12] Based on these conventional methods, dispersible zero dimensional (0D) structured LnPO 4 nanoparticles can be readily obtained, however, uniform 1D (rodlike) and 2D (disklike or polygonlike) nanostructured LnPO 4 NCs, that have regular shapes, have rarely been prepared by using the above synthetic systems.…”

Section: Introductionmentioning

confidence: 99%

Systematic Synthesis of Lanthanide Phosphate Nanocrystals

Huo

Chen

Chu

et al. 2007

113

Uniform LnPO(4).x H(2)O (Ln=Y, La-Nd, Sm-Lu) nanocrystals that have controllable 0D (spherelike), 1D (rodlike), and 2D (polygonlike) structures have been systematically synthesized by means of a hydrothermal method by using a mixed solvent of water and ethanol. Transmission electron microscopy images and SEAD (selected area electron diffraction) patterns revealed that the products are highly crystalline and have structurally uniform shapes. IR, Raman, and electron energy loss spectroscopies gave spectra that indicated that an amount of oleic acid molecules were presented at the surface of individual nanocrystals. These nanocrystals have hydrophobic surfaces and could be easily dispersed in nonpolar solvents. Moreover, a creditable synthetic mechanism for nucleation, growth, and shape evolution has been proposed. Eu(3+) doped products were also prepared by using the same synthetic process. The Eu(3+) doped products exhibited an orange-red luminescence that is ascribed to an electron transition within the 4f shell. Analysis of the photoluminescent spectra revealed that the optical properties are strongly dependent on their morphologies.