TY - JOUR A1 - Pohl, O. A1 - Kraft, Marco A1 - Kovac, J. A1 - Belec, B. A1 - Ponikvar-Svet, M. A1 - Würth, Christian A1 - Lisjak, D. A1 - Resch-Genger, Ute T1 - Optically detected degradation of NaYF4:Yb,Tm-based upconversion nanoparticles in phosphate buffered saline solution JF - Langmuir N2 - In a proof-of-concept study, we assessed different analytical and spectroscopic parameters for stability screening of differently sized β-NaYF4:20 mol % Yb3+, 2 mol % Tm3+ upconversion nanoparticles (UCNPs) exemplarily in the bioanalytically relevant buffer phosphate buffered saline (PBS; pH 7.4) at 37 and 50 °C. This included the potentiometric determination of the amount of released fluoride ions, surface analysis with X-ray photoelectron spectroscopy (XPS), and steady-state and time-resolved fluorescence measurements. Based on these results, the luminescence lifetime of the 800 nm upconversion emission was identified as an Optimum parameter for stability screening of UCNPs and changes in particle surface chemistry. KW - Upconverion KW - Nanoparticle KW - Dissolution PY - 2017 DO - https://doi.org/10.1021/acs.langmuir.6b03907 SN - 0743-7463 VL - 33 IS - 2 SP - 553 EP - 560 PB - ACS AN - OPUS4-39212 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -