Mesoporous lipid-silica nanohybrids for folate-targeted drug-resistant ovarian cancer

Folic acid (FA) targets cancer by exploiting its overexpression of folic acid receptors (FR). A novel folate conjugated lipid coated mesoporous silica nanoparticle has been synthesized in this study to enhance cellular uptake and cytotoxicity and reduce multidrug resistance (MDR) in cancer. Mesoporous silica nanoparticles (MSN) have a high loading capacity of doxorubicin (DOX) (0.012 mg mg(-1)) due to their high surface to volume ratio. On coating these nanoparticles (DOX: MSN) with a lipid composition of DPPC: cholesterol: DSPE-PEG2000: DSPE-PEG2000(folate) (DOX: FLMSN), a pH dependent sustained release property is achieved (similar to 20% to similar to 97% between pH 7.4-4.5 after 168 h of drug release). The system's cellular uptake efficiency was characterized against A2780(S), A2780-Cis-Res (showing FR overexpression) and PC3 cells (lacking FR overexpression). DOX: FLMSN shows significant improvement in cellular uptake in A2780(S) and A2780-Cis-Res but not in PC3 cells due to FR underexpression in the latter. However, in FA saturated media, the improvement is neutralized due to receptor blocking by free FA. Cytotoxicity studies confirm the enhanced cell growth inhibition of DOX: FLMSN over free DOX and DOX: LMSN in both A2780(S) and A2780-Cis-Res cells, thereby ameliorating MDR. Therefore, FA introduces active targeting in FR overexpressing cancer cells whilst simultaneously disrupting MDR. The nanoformulation of DOX: FLMSN can be further investigated in vivo.