Fluorescence lifetime nanothermometer based on the equilibrium formation of anthracene AIE-excimers in living cells

• Published in: Journal of colloid and interface science 2024-11, Vol.674, p.186-193
• Main Authors: Ripoll, Consuelo, del Campo-Balguerías, Almudena, Alonso-Moreno, Carlos, Herrera-Ochoa, Diego, Ocaña, Alberto, Martín, Cristina, Garzón-Ruíz, Andrés, Bravo, Iván
• Format: Article
• Language: English
• Subjects: Aggregation Induced Emission; Anthracene Aggregates; Breast Cancer; Fluorescence Lifetime Imaging Microscopy; Living Systems; Nanothermometer
• ISSN: 0021-9797; 1095-7103; 1095-7103
• DOI: 10.1016/j.jcis.2024.06.157

[Display omitted] The effective measurement of temperature in living systems at the nano and microscopic scales continues to be a challenge to this day. Here, we study the use of 2-(anthracen-2-yl)-1,3-diisopropylguanidine, 1, as a nanothermometer based on fluorescence lifetime measurements and its bioimaging applications. In aqueous solution, 1 is shown in aggregated form and the equilibrium between the two main aggregate types (T-shaped and π-π) is highly sensitive to the temperature. The heating of the medium shifts the equilibrium toward the formation of highly emissive T-shaped aggregates. This species shows a high fluorescence emission and a long lifetime in comparison with the π-π aggregates and the freé monomer. A linear relationship between the fluorescence lifetime and the temperature both in aqueous solution and in a synthetic intracellular buffer was found. Fluorescence lifetime imaging microscopy (FLIM) also showed a linear relationship between lifetime and temperature with an excellent sensitivity in MCF7 breast cancer cells, which opens the door for its potential use as FLIM nanothermometer in the biomedical field.