Ultra-thin phospholipid layers physically adsorbed upon glass characterized by nano-indentation at the surface contact level.
Dipalmitoylphosphatic acid was chosen as a model to interpret how molecules physically adsorbed upon glass responded to an infinitesimal oscillation force at the surface contact level. Oscillation of a nano-indentation tip toward the phospholipid layers was driven by a dynamic contact module at a constant harmonic frequency; the phase angle of the oscillation frequency was exponentially relaxed along the nano-scale displacement. The tip-on-molecule contact was thereafter identified and influenced by the characteristic of the physically adsorbed phospholipids. By applying the harmonic displacement of the nano-indentation tip and making a distinction between full contact displacements, the thickness of the phospholipid layers was thereafter estimated. Moreover, the additional force required to penetrate through the physically adsorbed molecules was minor compared to the analogous process for the chemically adsorbed ones. The importance of recognizing the physically adsorbed molecules is relevant to applications of contact mechanics for the distinction of various phospholipids. Furthermore it is very promising to interpret the mechanism by which cells convert mechanical stimuli into biochemical responses on the channels of phospholipids.
Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan.
Yun-Ta
YT
Yang
Jiunn-Der
JD
Liao
Yuh-Lang
YL
Lee
Chia-Wei
CW
Chang
Hui-Jung
HJ
Tsai
D000327:Adsorption; D005898:Glass / Q000737:chemistry*; D006244:Hardness; D006245:Hardness Tests; D008051:Lipid Bilayers / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008567:Membranes, Artificial; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D010743:Phospholipids / Q000737:chemistry*; D013499:Surface Properties
D008051:Lipid Bilayers; D046911:Macromolecular Substances; D008567:Membranes, Artificial; D010743:Phospholipids