Worakrit Saiyasombat, Sopon Nuchpun, Kanlaya Prapainop Katewongsa, Soraya Pornsuwan, Jan J. Weigand and Supavadee Kiatisevi *

The off–on bis-BODIPY fluorescent sensor, BODIPY-NN, effectively detects Cu²⁺ ions in aqueous solutions and images intracellular Cu²⁺ in living cells. Upon Cu²⁺ addition, BODIPY-NN exhibits fluorescence enhancement at 529 nm due to the inhibition of photo-induced electron transfer (PET) from the phenylenediamine–triazole unit to the BODIPY skeleton. This is triggered by oxidative C–N cyclization, forming a benzimidazole–triazole receptor that enhances metal ion binding efficiency. Cu²⁺ serves as both a catalyst for this cyclization and a coordination center, with a detection limit of 85 nM. BODIPY-NN has been successfully used for imaging Cu²⁺ in MCF-7 cells without toxicity, demonstrating its potential as a highly sensitive, non-cytotoxic fluorescent probe for in vivo bioimaging.

This research was financially supported by the Mahidol University (Basic Research Fund: fiscal year 2022). KK would like to thank the Central Instrument Facility (CIF) and Center of Nanoimaging (CNI), Faculty of Science, Mahidol University. SK would like to thank the NSRF via the Program Management Unit for Human Resources & Institutional Development, Research and Innovation (grant number B05F640128). The authors also thank Ruttanaporn Kriangsaksri for confocal microscopy support and Dr. Sitthivut Charoensutthivarakul for his experimental help. WS acknowledges the Science Achievement Scholarship of Thailand (SAST) for his scholarship. SN acknowledges the Development and Promotion of Science and Technology Talents Project (DPST) for his scholarship.

Reference:

W. Saiyasombat, S. Nuchpun, K. P. Katewongsa, S. Pornsuwan, J. J. Weigand, S. Kiatisevi, New J. Chem. 2022, 46, 22525-22532.