Upconversion nanoparticles with anti-Stokes luminescence as bioimaging agents Polina A. Demina, Evgeniy V. Khaydukov, Natalia V. Sholina, Vasilina V. Rocheva, Dmitry A. Khochenkov, Roman A. Akasov and Alla N. Generalova EPJ Web Conf., 190 (2018) 04005 Published online: 26 September 2018 DOI: 10.1051/epjconf/201819004005