Js. Salafsky et Kb. Eisenthal, Second harmonic spectroscopy: detection and orientation of molecules at a biomembrane interface, CHEM P LETT, 319(5-6), 2000, pp. 435-439
The adsorption and orientation of a dye molecule to a planar, glass-support
ed phospholipid bilayer, a widely-used model membrane for biological studie
s, was measured with second harmonic spectroscopy. The results indicate tha
t the positively charged dye binds at an angle of 19 degrees from the norma
l to the membrane plane. These results open the possibility of obtaining st
ructural information on a variety of other adsorbed molecules at phospholip
id membranes, including proteins, organic molecules and drugs. The nonlinea
r optical properties of the dye molecule are also demonstrated for the firs
t time and indicate that others in the oxaxole family may be useful for sec
ond harmonic generation studies. (C) 2000 Elsevier Science B.V. All rights
reserved.