Effect of acyl chain mismatch on the contact mechanics of two-component phospholipid vesicle during main phase transition.
It has been recently demonstrated that acyl chain mismatch of phospholipid bilayer composed of a binary lipid mixture induces component formation on the lateral plane of the bilayer [Biophys. J. 83 (2002) 1820-1883]. In this report, the contact mechanics of unilamellar vesicles composed of binary dimyristoyl-phosphatidylcholine (DMPC)/dipalmitoyl-phosphocholine (DPPC) mixtures on fused silica and amino-modified substrates is simultaneously probed by confocal-reflectance interference contrast microscopy (C-RICM) and cross-polarized light microscopy during gel to liquid crystalline transition of the lipid bilayer. C-RICM results indicate that the average degree of vesicle deformation for DMPC-rich and DPPC-rich vesicles adhering on fused silica substrate is increased by 30% and 14%, respectively, in comparison with that in pure DMPC and DPPC vesicles. Also, lateral heterogeneity induced by acyl chain mismatch increases the average magnitude of adhesion energy in DMPC-rich and DPPC-rich vesicles of all sizes by 6.4 times and 2.3 times, respectively. Similar modulation of adhesion mechanics induced by carbon chain difference is obtained on amino-modified substrate. Most importantly, the thermotropic transition of the mixed bilayer from gel (below T(m)) to fluid phase (above T(m)) further exemplifies the effect of acyl chain mismatch on the increases of degree of vesicle deformation and adhesion energy.
Fang
Ning
N
Tissue Engineering Laboratory, School of Mechanical and Production Engineering, Nanyang Technological University, MPE, 50 Nanyang Avenue, Singapore 639798, Singapore.
Lai
Alvin Chi-Keung
AC
Wan
Kai-Tak
KT
Chan
Vincent
V
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000268:Adhesiveness; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D008567:Membranes, Artificial; D008857:Microscopy, Interference; D008859:Microscopy, Polarization; D044367:Phase Transition; D010743:Phospholipids / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D013696:Temperature
D008567:Membranes, Artificial; D010743:Phospholipids; D015060:1,2-Dipalmitoylphosphatidylcholine; D012822:Silicon Dioxide; D004134:Dimyristoylphosphatidylcholine