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In this study, pH-sensitive dextran hydrogels were prepared from conjugation of dextran with glycidyl methacrylate (GMA), followed by copolymerization of modified dextrans with acrylic acid (AA) and N-t-butylacrylamide (BA). In addation, the formation of hydrogels by polymerization with ammonium peroxydisulfate (APS) and N,N,N',N'-tetra-methylethylenediamine (TMEDA) was examined. Characterization of the hydrogel system included equilibrium swelling ratio, swelling reversibility, crosslinking density and degradation. The results indicates that the swelling was strongly influenced by crosslinking density, the contents of acrylic acid and the pH of the media. The equilibrium swelling increased with increasing the contents of acrylic acid in hydrogels at high pH. The effective crosslinking density of hydrogels also increased with the polymer concentration and the degree of substitution by glycidyl methacrylate. The equilibrium swelling and degradation rates, however, reduced significantly with increasing the crosslinking density. Degradation of dextran hydrogels by dextranase shows that the weight of dry gels decreased with time, and the degradation rates also decreased with increasing crosslinking density of hydrogels.
於本研究中，我們利用聚葡萄糖（dextran）鍵結glycidyl methacrylate（GMA），並在ammonium peroxydisulfate（APS）與N,N,N’,N’-tetra-methylethylenediamine（TMEDA）為起始系統下，與acrylic acid（AA）及N-t-butylacrylamide（BA）進行自由基共聚合反應，以製備酸鹼敏感性聚醣類水膠。水膠的性質測試包括平衡膨潤測試（equilibrium swelling ratio）、可逆性質測試（reversibility）、交聯密度的測定（crosslinking density）與分解性質測試（degradation）。結果顯示水膠的膨潤程度受到交聯密度、acrylic acid含量及外界環境的影響。於高pH值時，acrylic acid含量較高的水膠具有高度膨潤現象。水膠有效交聯密度則會隨著高分子濃度與glycidyl methacrylate反應度之增加而增加。此兩變數亦影響水膠的平衡膨潤性質及分解的速率。在分解性質測試部分，由於水膠受到dextranase酵素的作用，其乾膠重量會隨著時間之增加而有遞減的趨勢。且其分解速率亦隨著水膠交聯密度的增加而有減緩的傾向。
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