title: Multicolor upconversion nanoparticles for protein conjugation.
abstract: We describe the preparation of monodisperse, lanthanide-doped hexagonal-phase NaYF4 upconverting luminescent nanoparticles for protein conjugation. Their core was coated with a silica shell which then was modified with a poly(ethylene glycol) spacer and N-hydroxysuccinimide ester groups. The nanoparticles were characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and dynamic light scattering. The N-hydroxysuccinimide ester functionalization renders them highly reactive towards amine nucleophiles (e.g., proteins). We show that such particles can be conjugated to proteins. The protein-reactive UCLNPs and their conjugates to streptavidin and bovine serum albumin display multicolor emissions upon 980-nm continuous wave laser excitation. Surface plasmon resonance studies were carried out to prove bioconjugation and to compare the affinity of the particles for proteins immobilized on a thin gold film.
authors.affiliation: University of Regensburg, Institute of Analytical Chemistry, Chemo- and Biosensors, 93040 Regensburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wilhelm
authors.forename: Thomas
authors.initials: T
authors.lastname: Hirsch
authors.forename: Wendy M
authors.initials: WM
authors.lastname: Patterson
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Scheucher
authors.forename: Torsten
authors.initials: T
authors.lastname: Mayr
authors.forename: Otto S
authors.initials: OS
authors.lastname: Wolfbeis
mesh_terms: D000418:Albumins / Q000737:chemistry*; D028581:Lanthanoid Series Elements / Q000737:chemistry; D049449:Luminescence; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D012822:Silicon Dioxide / Q000737:chemistry; D019809:Streptavidin / Q000737:chemistry*; D015019:Yttrium / Q000737:chemistry
chemical_list: D000418:Albumins; D028581:Lanthanoid Series Elements; D015019:Yttrium; D012822:Silicon Dioxide; D019809:Streptavidin
keywords: Raman spectroscopy; Upconversion luminescence; biosensing; magnetic separation; nanoparticle; silica coating; surface plasmon resonance.