Theranostics 2013; 3(4):239-248. doi:10.7150/thno.5113
Multicolor Upconversion Nanoparticles for Protein Conjugation
1. University of Regensburg, Institute of Analytical Chemistry, Chemo- and Biosensors, 93040 Regensburg, Germany.
2. Graz University of Technology, Institute of Analytical Chemistry and Food Chemistry, 8010 Graz, Austria.
Wilhelm S, Hirsch T, Patterson WM, Scheucher E, Mayr T, Wolfbeis OS. Multicolor Upconversion Nanoparticles for Protein Conjugation. Theranostics 2013; 3(4):239-248. doi:10.7150/thno.5113. Available from http://www.thno.org/v03p0239.htm
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.
Keywords: Upconversion luminescence, nanoparticle, silica coating, Raman spectroscopy, biosensing, magnetic separation, surface plasmon resonance.