Hypothesis: Sodium poly-γ-glutamate salt (γ-PGA) is a polyanionic, biocompatible, and hydrophilic biopolymer produced by Bacillus licheniformis. Due to its high water absorption capacity and interaction with blood components, it has been considered as a biological hemostatic agent. In this study, the effect of fermentation time on the molecular weight characteristics of γ-PGA and its relationship with the hemostatic performance of dressings prepared based on this polymer was investigated.
Methods: γ-PGA was produced through submerged fermentation in a synthetic culture medium and purified by alcoholic precipitation and dialysis. Sampling was performed at intervals of 14, 24, 48 and 72 h. The extracted polymers were impregnated onto rayon/polyester fabric by the immersion method, and hemostatic dressings corresponding to each fermentation time were prepared.
Findings: Gel permeation chromatography (GPC) analysis showed that although the average molecular weight of γ-PGA did not change significantly during the time period studied, its molecular weight distribution was markedly affected by fermentation time. With increasing fermentation time from 14 to 72 h, the relative amount of polymer in the higher molecular weight range (4-4.5×10⁶ Da) increased, as inferred from the increased area under the corresponding peaks, while the contribution of lighter oligomers decreased. These changes in molecular weight distribution and polymer content were accompanied by improved hemostatic performance, such that the blood coagulation index (BCI) increased from 80.68% in the dressing containing γ-PGA extracted at 14 h to 88.48% in the 72-h dressing. Accordingly, the dressing containing γ-PGA extracted at a fermentation time of 72 h was selected as the optimal sample for hemostatic and cytocompatibility evaluations. These results indicate that simultaneous control of fermentation time and molecular weight distribution of γ-PGA is an effective approach for optimizing the hemostatic performance of dressings and provides a suitable basis for the development of bioactive dressings with improved efficiency.