A protein amantadine-BODIPY assembly as a turn-on sensor for free copper(ii)

Copper ions are widely found in the environment and food. Free Cu(II) and Cu2+-protein complexes show different functions and toxicities. For example, the increase of free copper ions in the body can cause nervous system dysfunction, and liver and kidney damage. To develop a method for detection of free copper ions in biological tissues, an amantadine-conjugated 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene (BODIPY) compound (BOD-Ad) was synthesized. It is found that BOD-Ad can self-assemble with BSA forming non-emissive nanoparticles (BOD-Ad@BSA). Copper(II) induced the release of BOD-Ad from BOD-Ad@BSA with recovered fluorescence emission. Therefore, BOD-Ad@BSA can distinguish free copper(II) from protein-copper(II) complexes. Therefore, BOD-Ad@BSA is a turn-on fluorescent probe for free copper(II). Furthermore, BOD-Ad@BSA was used for the detection of the free Cu2+ content in fish samples bought from a supermarket.