pH响应型蔗渣木质素水凝胶的制备及其对蛋白质的控释性能

该研究以蔗渣木质素和甲基丙烯酸为原料合成了pH敏感型蔗渣木质素/聚甲基丙烯酸水凝胶,对其合成条件、pH敏感性、溶胀-退溶胀性能以及对牛血清蛋白的控释等性质进行研究,并采用红外光谱、扫描电镜等对凝胶进行表征。结果表明:(1)对凝胶溶胀比影响的因素由大到小依次为甲基丙烯酸用量、交联剂用量、催化剂用量、反应的温度、木质素用量。当甲基丙烯酸单体浓度为1.75 mol·L~(-1)、木质素浓度为25 g·L~(-1)、交联剂浓度为3.25×10~(-2)mol·L~(-1)、引发剂浓度为1.25×10~(-2)mol·L~(-1)、反应温度为65℃时,所得水凝胶在模拟肠液中的溶胀比最大(28.16 g·g~(-1))。与不加木质素的聚甲基丙烯酸水凝胶相比,蔗渣木质素/聚甲基丙烯酸水凝胶的溶胀比有所下降,但其敏感pH由4~5碱移至6~8。(2)蔗渣木质素/聚甲基丙烯酸水凝胶的溶胀—退溶胀可逆性受组成的影响较大,但相对于聚甲基丙烯酸水凝胶,蔗渣木质素/聚甲基丙烯酸水凝胶对pH值的敏感响应性更强、响应速率更快,同时能在更短时间内达到溶胀平衡。(3)加入木质素可以提高水凝胶对牛血清蛋白的负载量,所试验的蔗渣木质素/聚甲基丙烯酸水凝胶样品对牛血清蛋白的最大负载量可达577 mg·g~(-1)。(4)牛血清蛋白在12 h后基本可达释放平衡;在模拟胃液中,牛血清蛋白的释放率仅10%,而在模拟肠液中释放率达92%。pH响应型蔗渣木质素/聚甲基丙烯酸水凝胶可以作为口服型蛋白类药物的潜在载体。

Synthesis of pH-responsive hydrogel based on bagasse lignin and controlled release of protein

pH-responsive hydrogels were synthesized using the bagasse lignin and methacrylic acid as raw materials. The synthesis conditions, pH-responsive activities, swelling-deswelling properties and the controled release behaviour of bo- vine serum albumin for the synthesized hydrogels were studied. The gels were also characterized by IR and SEM. The re-sults were as follows:( 1) Orthogonal test results for the synthesis conditions of the hydrogels showed that the factors af-fecting the swelling ratio of the hydrogels in decreasing order were the amount of methyl acrylic acid, the amount of crosslinking agent, the amount of catalyst, the temperature of reaction, and the amount of lignin. Under the conditions of 1.75 mol·L-1 of methacrylic acid, 25 g·L-1 of lignin, 3.25 × 10-2 mol·L-1 of crosslinker, 1.25 × 10-2 mol·L-1 of cata-lyst and 65℃ of reaction temperature, the synthesized hydrogel possessed a maximum swelling ratio of 28.16 g·g-1 in simulated intestinal fluid. Compared with polymethacrylic acid hydrogels without of bagasse lignin, the swelling ratio of bagasse lignin/polymethacrylic acid hydrogels all were decreased moderately at different pH conditions. However, the addition of bagasse lignin made the sensitive pH of the hydrogels increased from pH 4-5 to pH 6-8. ( 2) Results of swelling-deswelling experiments showed that the addition of lignin made the swelling-deswelling reversibility of hydrogel vary by the components. However, compared to polymethacrylic acid hydrogels, bagasse lignin/polymethacrylic acid hy-drogel showed more sensitive response to pH and reached equilibrium in a shorter period of time. (3) Results of adsorp-tion tests showed that the addition of lignin to the hydrogel may increase the adsorption amount of bovine serum albumin. Among of the tested bagasse lignin/polymethacrylic acid hydrogel samples, the maximum loading capacity for bovine serum albumin was found to be 577 mg·g-1. (4) Results of controlled release tests showed that the release equi-librium for BSA could be reached after 12 h with a release rate of 10% in simulated gastric fluid and 92% in simulated intestinal fluid, respectively. As a natural and renewable resource, the utilization of bagasse lignin have been interested by researchers. Results of this study showed bagasse lignin/polymethacrylic acid hydrogels may be used as an potential polymer carrier for oral delivery of protein drugs and provided a possible way for the utilization of bagasse lignin.