酪蛋白-g-葡聚糖接枝共聚物对溶菌酶的负载和释放

用溶菌酶作为蛋白质药物模型, 研究了天然大分子对溶菌酶的包埋和释放. 蛋白质为天然的两性聚电解质. 通过Maillard反应制备了无毒且生物相容的β-酪蛋白和葡聚糖的接枝共聚物. 利用β-酪蛋白与溶菌酶之间的静电吸引力制备了以β-酪蛋白/溶菌酶为核, 葡聚糖为壳的胶束. 胶束在低浓度条件下可以稳定存在, 在酸、碱或盐条件下解离. 释放后的溶菌酶分子具有和天然的溶菌酶分子相同的活性. 在胶束中加入Ca2+离子可以使胶束在酸性条件下的稳定性增加. 当用疏水性更强的酪蛋白和葡聚糖接枝共聚物与溶菌酶形成胶束并用Ca2+离子交联后, 胶束在酸性环境下的稳定性显著提高, 在碱性和盐条件下的稳定性也有所增加.

Loading and Release of Lysozyme by Casein-g-dextran Graft Copolymer

Proteins are natural amphoteric polyelectrolyte. We studied the encapsulation and release of lysozyme as a model protein-drug using natural biomacromolecules. We prepared non-toxic β-casein-g-dextran copolymer through Maillard reaction and fabricated β-casein-g-dextran/lysozyme micelles through electrostatic attractive force between β-casein and lysozyme. The micelles with β-casein/lysozyme core and dextran shell are stable against dilution. The micelles dissociate in acidic, alkaline or salt solution where the electrostatic attraction disappears. The lysozyme released from the micelles shows the same activity as the nature lysozyme. Addition of Ca2+ ion can improve the stability of the micelles in acidic solution but cannot do so in alkaline or salt solution. Replacing β-casein-g-dextran with more hydrophobic casein-g-dextran and crosslinking the micelles with Ca2+ ion lead to the resultant micelles much more stable in acidic solution; the stability in alkaline or salt solution can also be improved.