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M. Kunioka
[Kobunshi Ronbunshu, Vol.50, No.10, pp.755-760, 1993]
Poly(γ-glutamic acid) (PGA) hydrogels have been prepared by means of γ-irradiation of PGA produced by Bacillus subtilis IFO3335 in aqueous solutions. When a dosage of γ-irradiation was 2 Mrad or more and a concentration of PGA in water was 2 wt% or more, transparent hydrogels could be produced. In the case of 2 Mrad of γ-irradiation and 5 wt% of PGA concentration, specific water content (wt of water/wt of polymer) of PGA hydrogel was approximately 3500. Specific water contents of PGA hydrogels decreased markedly with an increase in a dosage of γ-irradiation (Fig.). Swelling equilibria of PGA hydrogels were measured in water or in aqueous solutions of various pH's or concentrations of NaCl or CaCl_{2}. Under acid conditions or on addition of electrolytes, degrees of swelling of PGA hydrogels were smaller than that in distilled water.
