A velocity-gradient flow cell for Raman and emission spectroscopy of a deoxyribonucleic acid-drug solution.

A deoxyribonucleic acid (DNA) solution was placed in the gap (1 mm) between two coaxial cylinders; the inside diameter of the outer cylinder was 12 mm, and the outside diameter of the inner cylinder was 10 mm. When the inside cylinder was rotated at 2500 revolutions per minute, a sufficiently large velocity gradient of the liquid flow was produced across the gap so that the DNA molecules were oriented along the flow direction. Anisotropy of the Raman scatterings of the DNA molecule was examined by passing an exciting laser beam into the gap from the bottom of the cylinder in the direction parallel to the cylinder axis. An antitumor drug, aclacinomycin A (HCI salt), was added to the DNA solution, and the anisotropy of its emission and Raman spectra was also examined. It has been established that aclacinomycin binds to DNA with its chromophore oriented parallel to the base plane of the DNA duplex.