Liposome Based Near-Infrared Sensors for the Selective Detection of Hydrogen Sulfide

Cyanine dye-based new amphiphilic compound NIR-Amp has been synthesised. NIR-Amp was embedded with phospholipids DOPC and DPPC to form liposomes based nanoscale chemical sensors NIR-Lip1 and NIR-Lip2. Here, two different phospholipids were used to demonstrate the influence of lipid structure, composition and fluidity on sensing of nanosensors. Both the probes show NIR absorption maximum at 790 nm and emission maximum at 815 nm. H₂ S-triggered thiolation resulted a remarkable change in color from green to pale yellow. A decrease in UV-Vis absorption and emission in the NIR region was observed only with H₂ S. NIR-Lip1 and NIR-Lip2 are highly selective for H₂ S with a LOD of 0.57 μM and 1.24 μM, respectively. It was observed that in a solid-like gel state, NIR-Lip1 is slightly more sensitive towards H₂ S than fluid-like NIR-Lip2. The H₂ S sensing mechanism was confirmed by ESI-mass and infrared (IR) spectroscopic analysis. Based on the high sensitivity and selectivity, NIR-Lip1 was employed to detect H₂ S in vegetable samples. Further, the probes are found to be non-toxic and established for H₂ S fluorescence imaging in live cells.