Specific and sequential detection of hydrogen sulfide and hypochlorous
acid based on a ring-forming reaction and self-assembly
Abstract
Hydrogen sulfide (H2S) is an important molecule in
cellular physiology, serving various functions such as regulating blood
pressure, protecting cells against oxidative stress, modulating cellular
metabolism, and regulating cell survival and death. Another essential
biomolecule is hypochlorous acid (HClO), which is produced by white
blood cells to eliminate bacteria and viruses during infection. However,
excessive production of ClO– can lead to tissue
damage and contribute to many chronic diseases. Several fluorescent
probes have been developed for the sensitive and selective detection of
HS– and ClO–, but most of them are
designed to target only one of these analytes. Here we report a
sequential detection mode fluorescence probes P1-P3 that allow for the
sensing of HS– and ClO–. The
mixture of P and HS– constructs a specific sensing
system for ClO–, leading to significant fluorescent
quenching. Mechanism studies demonstrate that HS–
substitutes the Cl atom in P, which leads to fluorescence enhancement.
Furthermore, the addition of ClO– facilitates a
ring-forming reaction, resulting in the formation of a thiofuran ring
within the product (T) that quenches the fluorescence. Interestingly, P
has a highly ordered steric packing and could self-assemble into a
rice-spike-like structure. Upon the addition of HS–,
the assemblies decompose into free molecules. After interaction with
ClO–, these molecules further transform to T with
strong assembled capacity, featuring a larger number of nanosheets. This
study provides a novel mechanism for sensing HS– and
ClO–, cell and living animal imaging further
indicating the good application prospects of these probes in biosensing
and bioimaging.