Inside Cover, Volume 127, Issue 1


original image

A SEM image of the crosslinked γ -PGA/chitosan hydrogel with blending ratio of 0.01 is presented on the cover, and on page 832 by Tae-Il Son and colleagues. It shows the structural change at the surface of crosslinked hydrogel by blending γ—PGA to chitosan. Generally, chitosan hydrogel has a very bulky and uneven morphology, but the γ—PGA/chitosan crosslinked hydrogel has a homogeneous porous surface. Because chitosan has strong intermolecular hydrogen bonds, it aggregates during the process of chitosan hydrogel preparation, and a bulky surface forms between each pore in the hydrogel. However, because strong intermolecular hydrogen bonds are disturbed by the ionic interaction with c-PGA, c-PGA/chitosan hydrogel has no bulky surfaces.