Physico-Chemical Studies on Gelatin Gels Studies by Electrophoresis and Depolarization of Fluorescence

Abstract

A study was made of the behaviour in an electric field of microscopically visible particles (of dimensions 10,000 Å or more) in a gelatin gel. At 20°C the particles appeared to move regularly through gels of concentration up to lOg. gelatin/ 100ml. although the mobility was reduced as the gelatin concentration was increased. It is believed that whereas a true electrophoretic movement occurred before the gelatin set, on electro-osmotic fluid flow caused a progressive deformation of the firm gel and was responsible for the apparent movement of the entrapped particles. A study of the depolarization of the fluorescence from suitable dyes covalently bound to the gelatin molecule indicated that there was a considerable degree of rotational freedom of the gelatin molecules (or segments thereof) in solutions and gels, little change occurring with time or on gelation at constant temperature. The considerable effects of urea and sodium dodecyl sulphate upon the observed degree of polarization were also investigated. It was also shown that the freedom of rotation of the dissolved bovine serum albumin molecule was little altered by the presence of the gel.

Notes

Paper presented at a symposium on “Photographic Gelatin” organized by the Science Committee of the Royal Photographic Society on 19-22 September 1967 in Cambridge.