Upconverting nanoparticles for thermometry and singlet oxygen sensing applications in biological imaging

Abstract

Trivalent rare earth ions (RE3+) doped nanoparticles can exhibit upconversion phenomenon. This process consists in excitation of the material with two or more photons and, subsequently, emission of a higher energy photon. In this way, it is possible to use an excitation source in the biological window region and obtain UV-Visible-NIR emissions. The advantages of upconverting nanoparticles (UCNPs) for use in bioimaging are: high penetration of the radiation, UCNPs photostability, low signal/noise ratio and low secondary effects of near-infrared radiation. Temperature affects many cellular functions in living organisms and depends on chemical reactions which can release or absorb heat and disturb the internal temperature. Therefore, it is necessary to develop high-resolution temperature sensors to measure intracellular temperatures that can lead to novel insight about physiologic and pathophysiologic processes. Moreover, the detection of 1O2 is important because this molecule participates in many physiological and pathophysiological processes too. Therefore, we aim to investigate thermal and 1O2 sensors based on UCNPs to complement the work and prepare nanoparticles with a smaller size to upconverting single-molecule imaging applications. The knowledge of luminescent nanomaterials synthesis and redox processes of our group in IQ-USP will be combined with the expertise of upconverting single-molecule imaging, nanoinjector and UCNPs preparation of the Cohen group in the Molecular Foundry (Lawrence Berkeley National Laboratory). Needed to prepare and to investigate UCNPs as well as apply the sensors in single-molecule imaging will be provided by the Molecular Foundry (LBNL). The UCNPs will be applied in HeLa and GM00637 cell lines, and bioimaging will be performed. (AU)