Ratiometric fluorescence sensing of UiO-66-NH2 toward hypochlorite with novel dual emission in vitro and in vivo

Developing fluorescent probes to detect reactive oxygen species (ROS) is imperative to understanding the vital roles of ROS in various signaling and pathological processes. In this work, UiO-66-NH2 could be readily utilized as self-calibrating nanoprobe for selective detection and bioimaging of hypochlorite. Under the excitation of 400 nm, UiO-66-NH2 featured an emission at 432 nm and a new emission at 533 nm appeared after the addition of ClO-. Besides, the emission intensity of 533 nm increased with the incremental amount of ClO-. By using the ratio I533 nm/I432 nm as detection signal, UiO-66-NH2 could discriminate ClO- with high performance. The linear working range towards ClO- is 0.1–150 μM and the detection limit is 63.8 nM. In contrast to most other ratiometric sensors fabricated by physical entrapment methods, UiO-66-NH2 has the obvious advantage of effectively avoiding the worry of leakage of fluorophores from the nanomaterial matrix of sensors leading to erroneous measurements. Other amino-group functionalized MOF-based sensors such as MIL-53-NH2(Al) and MIL-101-NH2(Fe) exhibited similar fluorescence response toward ClO- as UiO-66-NH2. This work raises the possibility to develop highly specific and efficient probe for ClO- detection in vivo or in living cells and presents a new insight into ratiometric sensors.