Three-photon Absorption Cross-Sections of Serotonin, Fluorescein, Rhodamine 6G, and Some Fluorescent Protein Chromophores
Year: 2026
Type: preprint
Abstract: Interest in studying, enhancing the performance, and engineering of three-photon absorption (3PA) responsive molecular probes and bio-molecular systems, such as fluorescent proteins (FPs), has increased significantly over the last decade. 3PA has a deeper penetration than one-and two-photon absorption (1PA and 2PA, respectively). In particular, FPs can display 3PA within the deep tissue imaging window (1600-1870 nm). Experimentally, the 3PA ability (measured in terms of the 3PA cross-section, σ 3PA ) of a set of red fluorescent proteins (RFPs) has been reported before. On the other hand, just a handful of computational studies have determined the 3PA response and, in even fewer cases, determined the σ 3PA of selected FPs. By means of time-dependent density functional theory (TD-DFT) here we determine the σ 3PA of fluorescein, rhodamine 6G, serotonin, and a curated set of isolated FP chromophores for which their computationally determined 1PA and 2PA have been reported previously. The results from this investigation are in reasonably good agreement with their experimentally determined σ 3PA . We expect that in the future, our results for FP chromophores could be improved by the inclusion of effects of the protein, which are well-known to play important roles in determining the magnitude of 1PA, 2PA, and 3PA cross-sections. Finally, this investigation contributes to the understanding of multi-photon absorption photophysics of existent FPs and, furthermore, assists in the future engineering of new 3PA responsive FPs and FP chromophores.
Source: ChemRxiv
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Award: G4299827443
OpenAlex ID: W7213288641