title: Facile Synthesis of Amine-Functionalized Eu(3+)-Doped La(OH)3 Nanophosphors for Bioimaging.
abstract: Here, we report a straightforward synthesis process to produce colloidal Eu(3+)-activated nanophosphors (NPs) for use as bioimaging probes. In this procedure, poly(ethylene glycol) serves as a high-boiling point solvent allowing for nanoscale particle formation as well as a convenient medium for solvent exchange and subsequent surface modification. The La(OH)3:Eu(3+) NPs produced by this process were ~3.5 nm in diameter as determined by transmission electron microscopy. The NP surface was coated with aminopropyltriethoxysilane to provide chemical functionality for attachment of biological ligands, improve chemical stability and prevent surface quenching of luminescent centers. Photoluminescence spectroscopy of the NPs displayed emission peaks at 597 and 615 nm (λex = 280 nm). The red emission, due to (5)D0 → (7)F1 and (5)D0 → (7)F2 transitions, was linear with concentration as observed by imaging with a conventional bioimaging system. To demonstrate the feasibility of these NPs to serve as optical probes in biological applications, an in vitro experiment was performed with HeLa cells. NP emission was observed in the cells by fluorescence microscopy. In addition, the NPs displayed no cytotoxicity over the course of a 48-h MTT cell viability assay. These results suggest that La(OH)3:Eu(3+) NPs possess the potential to serve as a luminescent bioimaging probe.
authors: Department of Radiation Oncology, Stanford University School of Medicine, 875 Blake Wilbur Drive, Room G206, Stanford, CA, 94305-5847, USA. conroys@stanford.edu.
authors: Conroy
authors: C
authors: Sun
authors: Department of Radiation Oncology, Stanford University School of Medicine, 875 Blake Wilbur Drive, Room G206, Stanford, CA, 94305-5847, USA.
authors: Colin
authors: C
authors: Carpenter
authors: Department of Radiation Oncology, Stanford University School of Medicine, 875 Blake Wilbur Drive, Room G206, Stanford, CA, 94305-5847, USA.
authors: Guillem
authors: G
authors: Pratx
authors: Department of Radiation Oncology, Stanford University School of Medicine, 875 Blake Wilbur Drive, Room G206, Stanford, CA, 94305-5847, USA.
authors: Lei
authors: L
authors: Xing
keywords: Bioimaging; Europium; Lanthanum hydroxide; Nanoparticle synthesis; Nanophosphor; Photoluminescence