A polyoxometalate-based supramolecular chemosensor for rapid detection of hydrogen sulfide with dual signals.

Hydrogen sulfide (HS) has been verified as an important biological mediator in human physiological activities, but its rapid and accurate detection is remaining a challenge. Based on our early work, Eu-containing polyoxometalate/ionic liquid-type gemini surfactant hybrid nanoparticles fabricated by EuWO·32HO (Eu-POM) and 1,2-bis(3-hexadecylimidazolium-1-yl) ethane bromide ([C-2-Cim]Br) via ionic self-assembly (ISA) strategy, we modified the hybrids with copper (II) ion and used them as a novel turn-off supramolecular fluorescence probe for HS immediate response. Although copper (II) ions can cause decrease of the fluorescence intensity, the probe with moderate amount of copper (II) still has a high performance in emission property. The copper (II) ion-modified supramolecular sensor (CSS) shows dual signals in the fluorescence intensity and absorbance for HS detection, and the detection limit is about1.25μM. Furthermore, CSS displays high selectivity for HS in the presence of other anions and species (e.g. Cl, Br, I, SO, SO, SO, AC, HO, HCO, l-cysteine, homocysteine and l-glutathione), and also have potential for preferential imaging in vivo. Besides, the fluorescence quenching mechanism of CSS in the presence of HS was explored. CuS generated by the reaction between Cu and HS was testified to act as a quencher, and the nonradiative resonance energy transfer mechanism was speculated to be responsible for fluorescence quenching. It is anticipated that the as-prepared CSS will be used as an efficient chemosensor for the rapid detection of HS, which is critical for the diagnosis of some diseases, e.g. Alzhermer's disease, Down's syndrome, and diabetes, etc.