Hydrazide d-luciferin for in vitro selective detection and intratumoral imaging of Cu2+

• A chemosensor was developed for label-free, simple, and fast detection of Cu2+ in aqueous solution with high selectivity.
• This D-luciferin derivative chemosensor was applied for specific BL imaging of Cu2+ in tumors.
• This work demonstrates the first example of using BL for the in vitro selective detection and intratumoral imaging of a cation.

Copper is an essential micronutrient involved in fundamental life processes but using a bioluminescence (BL) probe to selectively sense Cu2+in vitro or image Cu2+in vivo is still unavailable. Herein, a latent BL probe hydrazide d-luciferin (1) was rationally designed and successfully applied it for selective detection of Cu2+in vitro and imaging Cu2+ in living cells and in tumors. Upon the catalysis of Cu2+, 1 was converted to d-luciferin and turned on the BL in the presence of firefly luciferase (fLuc). In vitro tests indicated that 1 could be applied for highly selective sensing Cu2+ within the range of 0–80 μM with a limit of detection (LOD) of 39.0 nM. Cell and animal experiments indicated that 1 could be applied for specific BL imaging of Cu2+ in living cells and tumors and the BL signal of 1 was more stable and longer than that of d-luciferin. We envision that this unique probe 1 might serve as an elucidative tool for further exploration of the biological roles of Cu2+ in physiological and pathological processes in the near future.