Rapid and highly sensitive detection of extracellular and intracellular HS by an azide-functionalized Al(iii)-based metal-organic framework.

A new, azide-functionalized Al(iii)-based metal-organic framework (MOF) denoted as CAU-10-N (1, CAU = Christian-Albrechts-University) and consisting of the 5-azido-isophthalic acid (HIPA-N) ligand was employed as a reaction-based fluorescent turn-on probe for the detection of HS. The activated compound (1') showed fast, selective and highly sensitive sensing properties for extracellular HS in HEPES buffer (10 mM, pH = 7.4). The material retained its high selectivity even in the presence of possibly competing biological species. The limit of detection of 1' for HS is 2.65 μM, which is lower than the earlier reports on MOFs for HS sensing. The material displayed a short response time (420 s) and a significant increase (20-fold and 26-fold after 1 and 7 min of addition of NaS, respectively) in the fluorescence intensity towards HS. Macrophage cells loaded with probe 1' exhibited blue fluorescence with a response time of 15 min after NaS addition, indicating the suitability of the probe for intracellular HS detection. Moreover, CAU-10-N featured excellent detection performance (quick response and 32-fold increment in fluorescence intensity after 7 min of NaS addition) in water. Hence, it can be utilized to regulate the HS level in aqueous samples collected from the environment.