海藻酸钠（SA）是一种天然的亲水性多糖是一种线性聚合物。从中我们可以看出，很快能凝胶层，凝胶层的大小，但是在两流体不同形式的结果。公司形成了较大的凝胶层在SGF比SIF了4mm在SGF和SIF只有2.5。它还需要更长的时间对凝胶在SIF的大小增加。核心宽度减少随着时间的推移和类似液体但总体略低在SGF在时间点。在两流体之间的凝胶层的宽度的差异表明，SA的水是依赖于pH SIF的pH值约为7.2，所以是中性的但是SGF具有pH在2到3是酸性。由于氢离子浓度的增加（在酸性条件下）有羧酸盐阴离子的相互转换（海藻酸钠）游离羧基（褐藻酸）。这意味着，在酸性条件下像SGF SA能够膨胀但不溶于水但溶于中性条件。因此，凝胶层会溶解在SIF和结果相比，SGF将有一个厚厚的凝胶层的宽度。因此，pH值的变化可能会改变聚合物和影响其在药物缓释作用的水化特性。
Sodium alginate (SA) is a natural hydrophilic polysaccharide and is a linear polymer. We can see from the results that it was rapidly able to form a gel layer however the size of the gel layer was different in the two fluids. SA formed a larger gel layer in the SGF than the SIF as it got to 4mm in the SGF and only 2.5 in the SIF. It also took longer for the gel to increase in size in the SIF. The core width decreased as time went on and were similar for both fluids but overall it was slightly lower in the SGF at the time points. The difference in the width of the gel layer between the two fluids shows that the hydration of SA is dependent on pH. SIF has a pH of around 7.2 so is neutral however SGF has a pH of around 2 to 3 making it acidic. As the concentration of hydrogen ions increase (in acidic conditions) there is inter-conversion of carboxylate anions (sodium alginate) to free carboxyl groups (alginic acid) . This means in acidic conditions like SGF SA is able to swell but is insoluble however it is soluble in neutral conditions. Therefore the gel layer may get dissolved in SIF and result in a lower width compared to SGF which would have a thick gel layer. Hence changes in pH are likely to alter the hydration characteristics of the polymer and effect its action on sustained drug release.
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