The important question regarding the enhancing effect of γ-CyD on transfection efficiency of pDNA/AF-liposomes still remains, because three types of HP-CyDs did not have the enhancing effect. To address this question, the DSC analysis was performed. This study indicated that γ-CyD, but not HP-γ-CyD, changed membrane fluidity and stabilized the N-liposomal membranes (Figure 9 ). In fact, γ-CyD increased the Tc value of DLPC-liposomes, although HPγ-CyD did not increase anymore ( Figure 10 ). This increase in the Tc value induced by γ-CyD could be attributed to a compactness of lipid bilayer of DLPC liposomes. It is thereby possible that γ-CyD may increase Tc values of the other liposomes such as DMPC, DPPC, and DSPC. Here, it is well known that γ-CyD is highly hydrophilic and surface inactive [17] . Therefore, we presumed that γ-CyD encapsulates the aqueous compartment of liposomes rather than in the bilayer of liposomes. Anyhow, it is clear that the magnification of the interaction of liposomal membranes containing DLPC with HP-γ-CyD is weaker than that with γ-CyD, possibly due to the steric hindrance of the HP group in a HP-γ-CyD molecule. Taken together, it is likely that the stabilizing effects of γ-CyD on AF-liposomal membrane may lead to inhibition of pDNA leakage from AF-liposomes and increase in cellular uptake of pDNA, eventually leading to the enhancement of in vitro transfection efficiency of pDNA/γ-CyD/AF-liposomes in cells.