November 8–9, 2017, Brno, Czech Republic 24 years CHARACTERIZATION OF UPCONVERSION NANOPARTICLES BY FLUORESCENCE SPECTROMETRY AND CAPILLARY ELECTROPHORESIS TEREZA VANECKOVA 1 , JAN ZITKA 1,2 , ANTONIN HLAVACEK 3 , VOJTECH ADAM 1,2 , MARKETA VACULOVICOVA 1,2 1 Department of Chemistry and Biochemistry Mendel University in Brno Zemedelska 1, 613 00 Brno 2 Central European Institute of Technology Brno University of Technology Purkynova 123, 612 00 Brno 3 Institute of Analytical Chemistry Czech Academy of Sciences Veveri 97, Brno CZECH REPUBLIC xvaneck1@mendelu.cz Abstract: Upconversion nanoparticles (UCNPs) are a novel class of luminescent tags for applications in life and material sciences. Unlike traditional fluorophores, UCNPs exhibit emission of shorter wavelength under near-infrared excitation (typically 980 nm). In this work, we have examined these unique photophysical properties by fluorescence spectrometry and capillary electrophoresis. UCNPs co-doped with Yb(III) and Er(III) were characterized using laboratory-made fluorescence spectrometer. We have exploited and evaluated two excitation sources and the dependence of the fluorescence of UCNPs on the relative excitation power. Moreover, capillary electrophoresis with laser-induced fluorescence (CE-LIF) detection was for the first time used for characterization of the nanoparticles. It was proved that CE-LIF is a valuable method to be used for investigation of upconversion luminiscence and monitoring of the interactions of UCNPs with other molecules of interest. Key Words: upconversion nanoparticles, UCNP, fluorescence spectrometry, capillary electrophoresis INTRODUCTION Lanthanide-doped photon upconversion nanoparticles (UCNPs) have been in the focus of research interest due to their unique photophysical properties. The anti-Stokes shifted luminescence is a result of a sequential photon absorption (Nadort et al. 2016, Zhu et al. 2017). Most upconversion materials rely on a crystalline host such as metal fluoride (most commonly NaYF4, CaF2), oxide (Y2O3), or phosphate (YPO4), and are co-doped with a single Ln 3+ ion or a combination of Ln 3+ such as Er 3+ , Yb 3+ , Tm 3+ Ho 3+ , and Gd 3+ (Gai et al. 2014). Advantageous features of UCNPs are basically no background due to anti-Stokes shifted emission (Zhu et al. 2017), low toxicity (Zhou et al. 2015), no photobleaching or photobrightening (Zheng et al. 2015, Zhou et al. 2015), applicability for long-term imaging (Wu et al. 2015), and particularly well suitability for deep tissue imaging (Wu et al. 2015, Xu et al. 2013, Yang 2014, Zhou et al. 2012). Therefore, UCNPs can in many ways overcome limitations of traditional fluorescent reporters, such as organic dyes or semiconductor nanocrystals (quantum dots). Due to their superior properties, a broad field of applications of UCNPs can be found. Recent progress enabled an increasing number of (bio)analytical (Hlavacek et al. 2016, Hlavacek et al. 2017, Chatterjee et al. 2010), diagnostic (Yang 2014), and sensing applications (Hao et al. 2013, Shi et al. 2015), as well as photovoltaic (Ramasamy et al. 2014) and security applications (Meruga et al. 2014). 953