Thiol-Responsive Fluorescent Nanoparticles Based On Assembly Of Betaine-Naphthalimide Amphiphiles

Abstract:Nano-carrier systems have several merits such as enhanced the solubility of hydrophobic anticancer drugs in water, targeted to the tumor tissues, prolonged circulation time and decreased side effects. Redox-responsive vehicles are mostly intended to disassemble and release drugs in the cytosol which contains2to3orders higher level of glutathione (GSH) than the extracellular fluids. The study of intracellular distribution of nano-carriers and loaded drugs also used fluorescent dyes and radiolabels. However, fluorescent markers may affect the delivery of drugs, and the radiolabel always leads to serious side effects to normal cells. Thus, the applying of a convenient method to monitor the nano-carriers and drugs distribution in vivo is of great importance.In this paper, we designed a new amphiphilic molecule compound8. This new molecule contains a fluorescent molecule naphthalimide with hydrophobic octadecane and hydrophilic betaine which can self-assemble into vesicles in water. To make the whole molecule response to thiol compounds, a disulfide bond was used to link naphthalimide and betaine. Compound8was characterized by1H-NMR,13C-NMR and ESI-MS. These self-assembled vesicles can respond to DTT, while the drug released from the nanoparticles, the fluorescence would be changed, it can be the instruction of the drug release. In this paper, we used fluorescence spectrophotometer to study the influence factors of vesicles response to DTT, including pH, DTT concentration and reductant agents. High performance liquid chromatography (HPLC) was used to research the mechanism of vesicles response to DTT. DLS showed the particle size distribution of the vesicle was uniform, the size distribution was80-120nm (PDI0.16). Square wave voltammetry was used to monitor drug release from the DOX-loaded vesicles. Confocal laser-scanning fluorescent microscopy images of Hela cells after exposure to DOX-loaded vesicles for2h and24h show that, in reaction to thiols in Hela cells, the disulfide bond was broken, the DOX was released from the vesicles and the fluorescence was changed simultaneously.