Study On The Applications Of Fluorescent Mesoporous Silica In The Release Of Anticancer Drug Doxorubicin

Owing to large surface area and pore volume, uniform and tunable pore diameter, low mass density, facile surface functionalization and good biocompatibility, mesoporous silica nanoparticles have been widely used in the fields of sensing, catalysis, biomedicine and environmental. However, there are still some problems in the field of biomedical:quantum dots (QDs) with a certain toxicity or dyes are used for cell tracing. The biocompatibility of the QDs and dyes have not been effectively confirmed yet. In addition, the drug loaded mesoporous silica nanoparticles could not be real-time monitoring of intracellular drug release into the cells. In view of the above-mentioned problems, we make the following two aspects:1. An autofluorescent mesoporous silica composite was developed by layer-by-layer assembly of chitosan (CHI)/dialdehyde starch (DAS) polyelectrolyte multilayers (PEM) onto mesoporous silica nanoparticles (MSN) surface. Folic acid (FA) had been conjugated to the outer surface of the mesoporous silica composites by the amide reaction in order to achieve targeted anticancer drug delivery. The formed mesoporous silica composites could be used as drug delivery carriers, which had very slow drug release rate at pH7.4, but had very fast drug release rate at pH5.0owing to the breakage of C=N bonds under acidic condition. It is found that cellular uptake of the folate conjugated doxorubicin-loaded nanoparticles in folate receptor-overexpressing HeLa cells is much higher than that of non-folate receptor-overexpressing A549cells.2. In situ formation method was adopted to prepare green fluorescence mesoporous silica nanoparticles (FMSN) as drug carrier and energy donor, and the anticancer drug doxorubicin as energy acceptor. Amino-PEG-Carboxyl (NH2-PEG-COOH) is conjugated to the outer surface of mesoporous silica at one end and modified by folate acid (FA) at the other end. The formed mesoporous silica composite combine the merits of fluorescent imaging, mesoporous nanostructure for drug loading, receptor-mediated targeting and real-time monitoring drug release. The resultant FA-grafted and PEGlated nanocomposites have excellent biocompatibility. It is found that the cytotoxicity of the loaded-DOX nanoparticles containing the folate targeting unites in folate-receptor-rich Hep2cancer cells is higher than that no folate targeting unites under the same conditions. When the DOX-FMSN-PEG-FA nanoparticles enter into the cells, the green fluorescence of the drug carrier gradually recover along with the release of DOX, so as to achieve the purpose of real-time monitoring of intracellular drug release.In summary, we have not only prepared the autofluorescent mesoporous silica composite, but also achieved real-time monitoring of intracellular drug release based on the mechanism of fluorescence resonance energy transfer. The functionalized mesoporous silica nanoparticles successfully wered used for the cell imaging and cancer therapy, which has great potentials in the field of medicine.