A nanosecond fluorometer for studies of rheological aspects of biomembranes

A nanosecond fluorometer was designed to study the microdynamics of biomembranes. The overall system consists of a nitrogen laser for excitation of fluorophores, optics consisting of polarizers, monochromators, a single photon counting system having a multichannel time to amplitude converter controlled with a microcomputer and a data processing system. The laser pulse for excitation was polarized with a polarizer. Anisotropically polarized DPH fluorescence could be measured with a time resolution smaller than 5 nsec. The parallel decay curve of DPH fluorescence was higher than the perpendicular decay curve in erythrocyte membrane over the whole decay time. No anisotropism was recorded in a tetrahydrofuran solution. These results suggested that the motion of DPH molecules in erythrocyte membranes was restrained and that the present system provided information on rheological aspects of molecular dynamic structure of biomembranes.