抄録
We have characterized molecular filtering behavior of two lipid molecules labeled with BODIPY derivatives. The difference of the structure is the functional group at the end of alkyl chain; methyl and thienyl. First, the filtering behavior for these two molecules was examined independently using the system of spreading bilayer through the metal nano-gate. By the fluorescence microscope observation, it was found that the molecule with thienyl was filtered more effectively. The filtering efficiency per nano-gate was about 9 % and 2 % for the molecule with thienyl and methyl, respectively. When these two molecules were incorporated in the self-spreading lipid bilayer, they were found to act as energy donor (methyl) and acceptor (thienyl), which resulted in the appearance of fluorescence resonant energy transfer (FRET). The FRET spectrum showed that the fluorescence intensity ratio of acceptor to donor continuously decreased during spreading through nano-gates. Judging from the result that the FRET efficiency is highly sensitive to not only dye concentration but also the molecular orientation or viscosity of the spreading bilayer, we conclude that the origin of the filtering efficiency can be discussed by monitoring the acceptor/donor intensity ratio in the bi-analyte incorporated system.
