Temperature is a crucial parameter in biology, medicine, chemistry and physics. Because of that, in the last years, several methods have been developed and presented to measure temperature at nanoscale level. Optical methods excel because they are non-invasive, spatially accurate and can measure real-time local changes in temperature. Among these, fluorescence anisotropy-based methods are particularly advantageous because they are less affected by changes in the probe concentration and irradiation conditions. Here we present the foundation of this method and its application for measuring intracellular temperature in cancer cells and live organism using the green fluorescent protein as a nanothermometer. In addition, it will be also described the methodology to add thermosensitivity to any protein or dye thereby transforming them into anisotropy-based nanothermometers. The process consists of covalently attaching a dye to the protein, which increases the rotational time of the dye-protein system compared to the free dye, and confers thermosensitivity to the resulting bioconjugates. With this method, it was transformed bovine serum albumin, glucose oxidase and catalase into nanothermoters. This also allow to analyze the anisotropy signal/temperature changes occurring during the catalytic cycle of catalase, as well as their correlation with the reaction exothermicity. Finally, we set up the theoretical model that predicts the optimal sensitivity for anisotropy-based thermometers based on protein size and dye fluorescence lifetime. Using this model, most of the proteins and dyes can be converted to anisotropy-based nanothermometers. The utilization of these nanothermometers by a broad spectrum of disciplines within the scientific community will bring new knowledge and understanding that today remains unavailable with current techniques.

Nano-scale intracellular temperature measurements using anisotropy-based nanothermometers

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.