Two dimensional phase separation of diacetylenic matrix and glycolipids atthe air-water interface

The interaction between recognition elements (e.g., receptors) and the phot ochromic diacetylenic matrix is of great importance in biosensor preparatio n. The characterization of the miscibility or phase separation of functiona lized components is an indispensable step for the design and preparation of biosensors. The interactions between 2,4-tricosadiynoic acid (TCDA) and di octadecyl glycerylether-beta-glucosides (DGG) as well as 10,12-pentacosadiy noic acid (PCDA) and DGG were studied by surface pressure-area isotherms an d Brewster angle microscopy. It has been found that for a mixed TCDA-DGG mo nolayer on water subphase, there existed good miscibility of TCDA and DGG. On the contrary, in a mixed PCDA-DGG monolayer, the miscibility of PCDA and DGG is poor; PCDA molecules easily separated from the mixed PCDA-DGG monol ayer during compression and formed a branch-like pattern. This result is co nsistent with the result obtained in pi-A isotherm and is discussed based o n the different position of the diacetylene group in the molecules.