Design And Synthesis Of An “AIE+ESIPT”-based H₂S Fluorescent Nanoprobe And Its Application In Bioimaging

Recently, H₂ S has been regarded as the third gasotransmitter besides nitric oxide（NO） and carbon monoxide（CO）, and it plays important roles in several pathophysiological processes, including vasodilation, regulation of cell growth,mediation of neurotransmission, and regulation of inflammation. Also, studies have shown that its deregulation is correlated with the symptoms of Alzherimer’s disease,Down’s syndrome, and liver cirrhosis. Therefore, the detection of H₂ S is of great significance in biology and medicine.Compared with the traditional detection methods, fluorescence-based assays have found widespread applications especially in biology, environment, materials,medicine and other fields due to the simplicity, high sensitivity, nondestructive detection, high spatiotemporal resolution, and real-time imaging of biological tissue.Liposome nanoparticles due to its large specific surface area, biodegradability,biocompatibility and good stability advantages, has been used for the detection,imaging of biological systems and drug delivery systems. Moreover, compared to neutral or anionic nanoparticles, cationic nanoparticles can accelerate the thiolysis reaction. In addition, surface functionalization of the liposome with cell penetrating peptides, such as Tat, yielded surface functionalized nanoparticles that can be internalized easily by cells and thus further improve the sensitivity of fluorescence imaging.In this paper, we firstly designed a visible light excitable fluorescent probe TPE-1 based on tetraphenylethene and 3-hydroxyflavone with “AIE+ESIPT”characteristics. Cationic liposome as efficient nanocarriers for probe TPE-1. The nano size, spectral properties and detection for hydrogen sulfide of the cationic liposome nanoprobe has been investigated and characterized. The average particle size of nanoprobe is about 72.31 nm with a narrow size distribution（PDI =0.218）. The nanoprobe is cationic with a Zeta potential of 56.9 mV. Spectral properties show that the cationic liposome nanoprobe appears an obvious emission peak at 550 nm afterspecific reaction with H₂ S and the fluorescence color changes from colorless to green.In addition, the nanoprobe has significant advantages: high sensitivity, quick responsibility, good selectivity and excellent anti-interference performance. And its detection limit is 55 nM. Besides, the biocompatibility of the cationic liposome nanoprobe is desirable, it can be used for quantitative detection and imaging of endogenous H₂ S in living cells. What’s more, it can be used for the imaging of exogenous H₂ S in zebrafish.