Abstract:

A water-soluble alkali lignin (AL) extracted from pine wood was used as raw material to prepared amphoteric lignin (AML-45) which used (3-chloro-2-hydroxypropyl)trimethylammonium chloride solution to chemical modify the AL by quaternization. AML-45 was activated in 8g/L NaOH, 12g/L urea and -10℃, then in alkaline medium activated AML-45 and polyethylene glycol diglycidyl ether were co-polymerized to prepare lignin-based pH-responsive hydrogel. The structures of AML-45 and lignin-based hydrogel were characterized by FTIR spectroscopy, DLS measurement. Scanning Electron Microscope was used to discover hydrogel's morphological characteristics. The swelling behavior of the hydrogel at different pH PBS-buffered solution was tracked. These results showed that the hydrogel was highly pH-responsive to a range of pH 2—7.4, with the swelling rate reaching minimum of 260%(pH=4) and maximum of 330% (pH=7.4). In addition, the swelling rate of hydrogel related to the lignin concentration, amount of cross-linker polyethylene glycol diglycidyl ether and 5-fluorouracil was used as model drug to explore its drug release behavior in buffer media in the acidic range (pH=2—7.4). The cumulative drug release from the loaded hydrogel in buffer solution (pH=7.4) was up to 78% within 30h which was higher than the cumulative drug release of 62% (pH=4) and 69% in (pH=2) in acidic buffer environment. The hydrogel had significantly drug retarded effect.

Key words: lignin, hydrogel, pH responsiveness, polymers, pharmaceuticals, biomass, gels

摘要：

以从松木提取的水溶性碱木质素（AL）为原料，利用3-氯-2-羟丙基三甲基氯化铵对AL进行季铵化改性，成功制备一种阴阳离子两性木质素（AML-45）。在8g/L NaOH、12g/L尿素和-10℃环境中对AML-45进行活化，活化后在碱性介质中与聚乙二醇二缩水甘油醚（PEGDGE）共聚合成制备木质素基pH响应性水凝胶。通过傅里叶红外光谱仪和激光粒度分析仪（DLS）等对AML-45和AML-45基水凝胶结构进行表征，利用扫描电子显微镜对木质素基水凝胶的形貌特征进行表征，研究该水凝胶在不同pH的PBS缓冲溶液中的溶胀行为。结果显示，水凝胶具有明显的pH响应性，在酸性范围内，当pH为4时溶胀率最低为260%，pH为7.4时最高可达到330%。此外，水凝胶的溶胀率与AML-45浓度、交联剂PEGDGE用量和反应环境pH有关。以5-氟尿嘧啶作为模型药物，探讨其在酸性范围内（pH=2~7.4）缓冲介质中药物释放行为。在30h内，负载药物后的水凝胶在缓冲溶液（pH=7.4）中的药物累积释放量可达78%，高于酸性缓冲环境（pH=4）的62%和（pH=2）69%药物累积释放量，故此水凝胶有明显的药物缓释作用。

关键词: 木质素, 水凝胶, pH响应性, 聚合物, 药物, 生物质, 凝胶