Department of Chemistry , Wake Forest University , 455 Vine Street , Winston-Salem , North Carolina 27101 , United States.
Wake Forest Institute for Regenerative Medicine , Wake Forest School of Medicine , Medical Center Boulevard Winston-Salem , North Carolina 27101 , United States.
J Agric Food Chem. 2019 Sep 18;67(37):10481-10488. doi: 10.1021/acs.jafc.9b01911. Epub 2019 Sep 4.
Here, we report two methods that chemically modify alginate to achieve neutral-basic pH sensitivity of the resultant hydrogel. The first method involves direct amide bond formation between alginate and 4-(2-aminoethyl)benzoic acid. The second method that arose out of the desire to achieve better control of the degradation rate of the alginate hydrogel involves reductive amination of oxidized alginate. The products of both methods result in a hydrogel vehicle for targeted delivery of encapsulated payload under physiological conditions in the gastrointestinal tract. Two-dimensional diffusion-ordered spectroscopy and internal and coaxial external nuclear magnetic resonance standards were used to establish chemical bonding and percent incorporation of the modifying groups into the alginate polymer. The hydrogel made with alginate modified by each method was found to be completely stable under acidic pH conditions while disintegrating within minutes to hours in neutral-basic pH conditions. We found that, while alginate oxidation did not affect the β-d-mannuronate/α-l-guluronate ratio of alginate, the rate of disintegration of the hydrogel made with oxidized alginate was dependent upon the degree of oxidation.
在这里，我们报告了两种化学修饰海藻酸盐的方法，以实现所得水凝胶在中性-碱性 pH 值下的敏感性。第一种方法涉及海藻酸盐与 4-(2-氨基乙基)苯甲酸之间的直接酰胺键形成。第二种方法源于对更好地控制海藻酸盐水凝胶降解速率的需求，涉及氧化海藻酸盐的还原胺化。这两种方法的产物都导致了一种水凝胶载体，用于在胃肠道的生理条件下靶向递送包封的有效成分。二维扩散有序光谱和内标和同轴外标核磁共振用于建立化学键合以及修饰基团在海藻酸盐聚合物中的百分含量。发现用这两种方法之一修饰的水凝胶在酸性 pH 值条件下完全稳定，而在中性-碱性 pH 值条件下几分钟到几小时内就会分解。我们发现，虽然海藻酸盐氧化不会影响海藻酸盐的β-d-甘露糖醛酸/α-l-古洛糖醛酸盐比例，但氧化海藻酸盐制成的水凝胶的分解速率取决于氧化程度。
