The present paper explores the effect of boric acid on Chitlac, a lactose-modified chitosan which had previously shown interesting biological and physical-chemical features. The herewith-reported experimental evidences demonstrated that boric acid binds to Chitlac, producing conformational and association effects on the chitosan derivative. The thermodynamics of boric acid binding to Chitlac was explored by means of ¹¹B NMR, circular dichroism (CD), and UV–vis spectroscopy, while macromolecular effects were investigated by means of viscometry and dynamic light scattering (DLS). The experimental results revealed a chain–chain association when limited amounts of boric acid were added to Chitlac. However, upon exceeding a critical boric acid limit dependent on the polysaccharide concentration, the soluble aggregates disentangle. The rheological behavior of Chitlac upon treatment with boric acid was explored showing a dilatant behavior in conditions of steady flow. An uncommonly high dependence in the scaling law between the zero-shear viscosity and the concentration of Chitlac was found, i.e., η₀ ∝ C_CTL^5.8, pointing to interesting potential implications of the present system in biomaterials development.

中文翻译：

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硼酸在乳糖修饰的壳聚糖（Chitlac）中诱导的瞬时交联

本文探讨了硼酸对Chitlac的影响，Chitlac是一种乳糖修饰的壳聚糖，以前已显示出有趣的生物学和物理化学特征。此处报告的实验证据表明，硼酸与Chitlac结合，对壳聚糖衍生物产生构象和缔合作用。硼酸与Chitlac结合的热力学通过¹¹B NMR，圆二色性（CD）和UV-vis光谱学，而大分子效应则通过粘度测定法和动态光散射（DLS）进行了研究。实验结果表明，当将少量硼酸添加到Chitlac中时，链与链之间的缔合。然而，当超过取决于多糖浓度的临界硼酸极限时，可溶性聚集体解开。考察了Chitlac用硼酸处理后的流变行为，显示了在稳定流动条件下的膨胀行为。在零剪切粘度和Chitlac中的浓度之间的比例定律的罕见高依赖性被发现，即，η ₀ α Ç _CTL ^5.8指出了当前系统在生物材料开发中的有趣潜在影响。