The microfluidity and dissolution of hydrogenated PC liposome anchored with alkyl grafted poly(amino acid)s

Abstract

The stability of a polymer hybridized liposome (PHL) was examined with the microfluidic and thermal state of anchored alkyl chains, and with dissolution against deoxycholate (DOC). Poly(asparagine) grafted with octadecylamine (PAsn-g-C-18), poly(aspartic acid) grafted with octadecylamine (PAsp-g-C-18), and poly(aspartic acid) grafted with phytosphingosine (PAsp-g-PHS) were synthesized. The microfluidity of the membrane of the PHL was evaluated by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and the phase transition temperature (T-c) was measured by differential scanning calorimetry (DSC). The membrane fluidity of liposomes was increased by the inclusion of amphiphilic graft polymers. The phase transition temperature of liposomes increased by the anchoring of PAsn-g-C-18, while the inclusion of PAsp-g-C-18 or PAsp-g-PHS lowered the T-c. The surface charge of PHL of PAsn-g-C-18 was changed by the cationic lipid content. The structural stability of the PHL was affected by variation of the hydrophilic backbone or the hydrophobic moiety of the polymer and PHL of PAsn-g-C-18 was most stable against DOC. An increased degree of substitution of the graft copolymer led to better stability of the PHL It was found that the polymer characteristics affect the physicochemical strength of the PHL structure, resulting in different degrees of stability enhancement. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.