TY - CONF A1 - Resch-Genger, Ute T1 - Simple method for the quantification of PEG ligands and guidelines to the spectroscopic characterization of upconversion nanoparticles N2 - The surface modification of nanometer- and micrometer-sized particles with polyethylene glycol (PEG) ligands of varying length is a very common strategy to tune their hydrophilicity and biocompatibility, minimize unspecific interactions, improve biofunctionalization efficiencies, and enhance blood circulation times. Nevertheless, simple methods for the quantification of PEG ligands are rare. This is similarly true for the spectroscopic characterization of lanthanide-doped upconverting nanoparticles (UCNPs), novel near infrared (NIR)-excitable nonlinear fluorescence reporters for bioanalysis and theranostics, providing background-free multiple narrow emission bands in the visible and NIR, excellent photostability, and long luminescence lifetimes. We present here a simple method for the determination of the number of PEG ligands on nanomaterials and screening methods for the fast identification of nonradiative deaction pathways in UCNPs. T2 - SPIE Photonics West CY - San Francisco, CA, USA DA - 15.02.2016 KW - Optical assay KW - Fluorescence KW - Integrating sphere spectroscopy KW - Quantum yield KW - NIR KW - IR KW - Optical spectroscopy KW - Nanomaterials KW - Semiconducor nanocrystals KW - Upconversion nanocrystals KW - Surface analysis; KW - Ligand analysis PY - 2016 AN - OPUS4-35951 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -