Some aspects of the crosslinking of gelatin by dextran dialdehydes

The present paper describes the formation of hydrogels by reaction of gelatins with periodate oxidized dextrans. The effect of a number of reaction parameters on the rate of gelation is investigated. It is demonstrated that the time to onset of gelation depends on the nature of the gelatin, the nature of the dextran dialdehyde, the type of buffer, the ionic strength and the presence of added salts. The gelation time decreases with increasing concentration of aldehydes, increasing pH and increasing molecular weight of the dextran dialdehyde. In general, the gelation occurs more rapidly with decreasing concentration of indifferent electrolytes, except for the reaction in phosphate buffer where an increase in gelation is observed with increasing buffer strength. Ammonium and calcium salts are found to retard significantly the crosslinking reaction.