Synthesis of folate-chitosan nanoparticles loaded with ligustrazine to target folate receptor positive cancer cells

In addition to its vasodilatory effect, ligustrazine (LZ) improves the sensitivity of multidrug resistant cancer cells to chemotherapeutic agents. To enhance the specificity of LZ delivery to tumor cells/tissues, folate-chitosan nanoparticles (FA-CS-NPs) were synthesized by combination of folate ester with the amine group on chitosan to serve as a delivery vehicle for LZ (FA-CS-LZ-NPs). The structure of folate-chitosan and characteristics of FA-CS-LZ-NPs, including its size, encapsulation efficiency, loading capacity and release rates were analyzed. MCF-7 (folate receptor-positive) and A549 (folate receptor-negative) cells cultured with or without folate were treated with FA-CS-LZ-NPs, CS-LZ-NPs or LZ to determine cancer-targeting specificity of FA-CS-LZ-NPs. Fluorescence intensity of intracellular LZ was observed by laser scanning confocal microscopy, and concentration of intracellular LZ was detected by HPLC. The average size of FA-CS-LZ-NPs was 182.7 +/- 0.56 nm, and the encapsulation efficiency and loading capacity was 59.6 +/- 0.23 and 15.3 +/- 0.16% respectively. The cumulative release rate was about 95% at pH 5.0, which was higher than that at pH 7.4. There was higher intracellular LZ accumulation in MCF-7 than that in A549 cells and intracellular LZ concentration was not high when MCF-7 cells were cultured with folate. These results indicated that the targeting specificity of FA-CS-LZ-NPs was mediated by folate receptor. Therefore, the FA-CS-LZ-NPs may be a potential folate receptor-positive tumor cell targeting drug delivery system that could possibly overcome multidrug resistance during cancer therapy.