TY - JOUR
T1 - Microcalorimetric studies on the physical stability of poly-ethylene glycol-grafted liposome
AU - Liu, Der Zen
AU - Hsieh, Yi Ling
AU - Chang, Sheng Yen
AU - Chen, Wen Yih
PY - 2003/1/23
Y1 - 2003/1/23
N2 - Liposomes were prepared from mixtures of egg-PC, cholesterols and distearoyl-phosphatidyl-ethanolamine covalently attached poly-ethylene glycol (PEG) with a molecular of weight 2000 (DSPE-PEG2000). In this work examines how PEG2000-grafted lipids affect the surface properties of the egg phosphatidylcholine (egg-PC) liposomal bilayer membrane through zeta potential and interaction potential measurements using microcalorimetry. Experimental results demonstrate that the absolute value of the zeta potential of PEG2000-grafted PC liposomes decreased from -19 to -8 mV when increasing DSPE-PEG2000 from 0 to 7 mol fraction, and the repulsive interaction potential of PEG2000-grafted PC liposomes decreased compared with those liposomes without PEG-grafting. However, the phenomenon of fusion between the liposomes incorporated with PEG-grafted PC was reduced. In brief, this result of fusion is contrary to the expectation of the interaction potential measurement; therefore, we believe that the steric hindrance of the grafted PEG2000 molecules on the liposomal surface contribute to a major imposition on the approach between liposomal surface and the formation of inverted micelles which are suggested as the necessary steps of liposome fusion.
AB - Liposomes were prepared from mixtures of egg-PC, cholesterols and distearoyl-phosphatidyl-ethanolamine covalently attached poly-ethylene glycol (PEG) with a molecular of weight 2000 (DSPE-PEG2000). In this work examines how PEG2000-grafted lipids affect the surface properties of the egg phosphatidylcholine (egg-PC) liposomal bilayer membrane through zeta potential and interaction potential measurements using microcalorimetry. Experimental results demonstrate that the absolute value of the zeta potential of PEG2000-grafted PC liposomes decreased from -19 to -8 mV when increasing DSPE-PEG2000 from 0 to 7 mol fraction, and the repulsive interaction potential of PEG2000-grafted PC liposomes decreased compared with those liposomes without PEG-grafting. However, the phenomenon of fusion between the liposomes incorporated with PEG-grafted PC was reduced. In brief, this result of fusion is contrary to the expectation of the interaction potential measurement; therefore, we believe that the steric hindrance of the grafted PEG2000 molecules on the liposomal surface contribute to a major imposition on the approach between liposomal surface and the formation of inverted micelles which are suggested as the necessary steps of liposome fusion.
KW - Interaction potential
KW - Physical stability
KW - Poly-ethylene glycol-liposome
KW - Zeta potential
UR - http://www.scopus.com/inward/record.url?scp=0037461554&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037461554&partnerID=8YFLogxK
U2 - 10.1016/S0927-7757(02)00306-0
DO - 10.1016/S0927-7757(02)00306-0
M3 - Article
AN - SCOPUS:0037461554
SN - 0927-7757
VL - 212
SP - 227
EP - 234
JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects
JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects
IS - 2-3
ER -