Dual hypochlorite and adenosine-5’-triphosphate responsive ZIF-90 nanosystem and its application for biological imaging

Hypochlorite ion (ClO⁻) and adenosine-5’-triphosphate (ATP) are crucial in various physiological functions. The connection between ClO⁻ and ATP has been noted as one of the major characteristics of liver injury. This study presents a zeolitic imidazolate framework (ZIF-90)-based probe RhB@MP-ZIF-90 for the simultaneous identification of ClO⁻ and ATP, which was fabricated by in situ encapsulation of rhodamine B (RhB) and successive modification of 4-methyl-1-(4-(4,4,5,5-tetramethyl-1,3,2-dioxa-borolan-2-yl)benzyl)pyridinium bromide (MP). A well-dispersed aqueous solution of this nano-scale probe is highly emissive in the green channel due to the charge transfer from ZIF-90 to the pyridinium. ClO⁻ oxidizes the boronate ester group to hydroxyl in probe RhB@MP-ZIF-90, which is accompanied by the elimination of 4-methylene-cyclohexa-2,5-dienone, changing pyridinium to pyridine, blocking ICT, and quenching the green emission. By contrast, the ZIF-90 backbone of the probe is destroyed by ATP, releasing RhB to generate a characteristic red emission. Thus, this easy-to-prepare probe enabled the dual detection of ClO⁻ and ATP, achieved through ClO⁻-triggered fluorescence decrease and ATP-induced fluorescence amplification in two independent channels, with detection limits of 24.94 μM for ClO⁻ and 360 μM for ATP, respectively. As such, RhB@MP-ZIF-90 was successfully used to monitor concentration changes of mitochondrial ClO⁻ and ATP in different biological processes and a drug-induced liver injury model.