The effects of radiation on tissue have generally been investigated in the context of therapeutic
irradiations, radiation protection and exposure to solar radiation. Typically attention has
concentrated primarily on cells, less consideration being given to the extracellular matrix (ECM).
ECM consists of collagen and elastin fibers immersed in a viscoelastic gel composed principally of
hyaluronan (HA) and proteoglycans. The present study examines changes in the physical properties of
the principle matrix micromolecules due to exposure to ionizing radiation. Freeze-dried rooster-comb
HA (Sigma) were used to give doses of 10-100 Gy for HA, to cover the range of irradiation exposure
during radiotherapy. The viscosity of HA (at 1.25% and 0.125% w/v) was measured by both cone and
plate and capillary viscometry, the former providing measurement at uniform shear rate and the latter
providing a more sensitive indication of changes. The Raman microspectrometry was employed to
characterize these changes on ECM molecular conformation. In regard to the viscometry, both
techniques (cone and plate and capillary viscometry) reveal a dose-dependent reduction in viscosity
(from 340 ± 194 cP for controls to 1500 ± 88 cP at a shear rate of 2 s-1 and dose of 75 Gy), again
suggesting depolymerisation.