Real-time imaging of intracellular drug release from mesoporous silica nanoparticles based on fluorescence resonance energy transfer

-PEG-COOH is conjugated to the outer surface of the FMSN at one end and modified by folic acid at the other, so that the formed mesoporous silica composite has the merits of fluorescence imaging, mesoporous nanostructure for drug loading, receptor-mediated targeting and real-time monitoring of intracellular drug release. It was found that the FA-grafted and PEGlated nanocomposite has excellent biocompatibility towards Hep2 cells, and that the cytotoxicity of the loaded-DOX nanoparticles, containing the folate targeting units in the folate-receptor-rich Hep2 cancer cells, is higher than that without folate targeting units, under the same conditions. When the resultant nanoparticles enter into the cells, the green fluorescence of FMSN gradually recovers along with the release of DOX, to achieve the purpose of real-time monitoring of intracellular drug release.