pH-sensitive β-cyclodextrin derivatives for the controlled release of Podophyllotoxin

An effective tumor targeting drug delivery systems was designed and synthesized by conjugating pH-sensitive maleamide derivatives to Mono-(6-deoxy-6-amino)-β-CD. Their characteristics and inclusion behaviors with insoluble anticancer drug PPT were investigated in both solution and solid state by means of 1H NMR and 2D-ROESY, XRD, DSC and SEM, which reveal PPT is successfully encapsulated in the cavity of CD derivatives with different stability constants (Ks). Water solubility of PPT are significantly increased to 60.35 and 22.89 mg·mL−1 after formation of inclusion complexes with host-1 and host-2, compared with free PPT (0.12 mg·mL−1). Their acid-controlled release has been studied in vitro by 1H NMR and UV-Vis spectra, living cells incubated with host 1-2 were observed by Inverted fluorescence microscope to confirm pH-response releasing. Moreover, host-1/PPT and host-2/PPT maintain effective cell proliferation inhibition to human cancer, while their cytotoxicity to normal cell is significantly reduced. Our work shows inspiring potential in tumor-targeted delivery and acid-controlled release of PPT both in vitro.