For all kinds of liposomes, Qad was found to increase along with liposome concentration, with the obtained isotherm exhibiting an IUPAC type I isotherm (Figure ). Maximum quantity adsorbed (Qmax) and adsorption equilibrium constant (K) were determined by fitting with Langmuir isotherm equation (Table ). It appeared that the smaller anionic liposomes are, the higher Qmax values are. This can be interpreted by more efficient packing into the pores of smaller liposomes compared to larger ones. On the other hand, larger liposomes showed higher K value over smaller ones. This may be due to relatively efficient ion-exchange property for larger liposomes due to their larger surface area close to the pore wall.