Formation of supported lipid bilayers on silica: relation to lipid phase transition temperature and liposome size

• Published in: Soft matter Vol. 1; no. 1; pp. 187 - 195
• Main Authors: Jing, Yujia, Trefna, Hana, Persson, Mikael, Kasemo, Bengt, Svedhem, Sofia
• Format: Journal Article
• Language: English
• Published: England 01.01.2014
• Subjects: DIOXIDE; HYPERTHERMIA; Lipid Bilayers - chemical synthesis; Lipid Bilayers - chemistry; Lipids; Lipids - chemistry; Liposomes - chemistry; MEMBRANES; Particle Size; Phase Transition; PHOSPHOLIPID-BILAYERS; QCM-D; RUPTURE; Silicon Dioxide - chemistry; SIMULATIONS; SURFACE; Surface Properties; Temperature; THERMOSENSITIVE LIPOSOMES; VESICLE ADSORPTION
• ISSN: 1744-683X; 1744-6848; 1744-6848
• DOI: 10.1039/c3sm50947h

DPPC liposomes ranging from 90 nm to 160 nm in diameter were prepared and used for studies of the formation of supported lipid membranes on silica (SiO 2 ) at temperatures below and above the gel to liquid-crystalline phase transition temperature ( T m = 41 °C), and by applying temperature gradients through T m . The main method was the quartz crystal microbalance with dissipation (QCM-D) technique. It was found that liposomes smaller than 100 nm spontaneously rupture on the silica surface when deposited at a temperature above T m and at a critical surface coverage, following a well-established pathway. In contrast, DPPC liposomes larger than 160 nm do not rupture on the surface when adsorbed at 22 °C or at 50 °C. However, when liposomes of this size are first adsorbed at 22 °C and at a high enough surface coverage, after which they are subject to a constant temperature gradient up to 50 °C, they rupture and fuse to a bilayer, a process that is initiated around T m . The results are discussed and interpreted considering a combination of effects derived from liposome-surface and liposome-liposome interactions, different softness/stiffness and shape of liposomes below and above T m , the dynamics and thermal activation of the bilayers occurring around T m and (for liposomes containing 33% of NaCl) osmotic pressure. These findings are valuable both for preparation of supported lipid bilayer cell membrane mimics and for designing temperature-responsive material coatings. DPPC liposomes (160 nm) overcome size dependent rupturing limitations on silica by temperature ramping through the phase transition temperature ( T m ).