Department of Chemical Engineering, Institute of Chemical Technology, N.P. Marg, Matunga, Mumbai 400019, India; Department of Pharmaceutical Sciences & Technology, Institute of Chemical Technology, N.P. Marg, Matunga, Mumbai 400019, India.
Department of Pharmaceutical Sciences & Technology, Institute of Chemical Technology, N.P. Marg, Matunga, Mumbai 400019, India.
Carbohydr Polym. 2016 Oct 20;151:417-425. doi: 10.1016/j.carbpol.2016.05.082. Epub 2016 May 24.
Low molecular weight chitosan (LWCS) constitute a special class of value added chemicals that are primarily obtained from crustacean shells, which are the main water pollutants from crabs and shrimp processing centers. Unlike chitin and chitosan, LWCS possess improved solubility in water and aqueous solutions, making them widely applicable in numerous fields ranging from drug delivery to waste water treatment. Among the methods employed for their production, chemical breakdown by strong liquid acids has yielded good success. However, this method is met with severe concerns arising from the harsh nature of liquid acids, which may corrode the reactors for commercial synthesis, and their limited reusability. The physical methods like ultrasound and microwave are energy intensive in nature, while the enzymatic methods are expensive and offers limited scope for reuse. We have attempted to overcome these problems by employing carbon based solid acid (CSA) for hydrolyzing chitosan to LWCS. CSA can be easily produced using activated carbon, a cost-effective and easily available raw material. Reactions were carried out between chitosan and CSA in a hydrothermal glass reactor and the products, separated by cold centrifugation, were purified and dried. The dried products were characterized for their molecular weight and solubility. Results indicated more than ten-fold decrease in the molecular weight of chitosan and the product exhibited water solubility. The CSA could be used upto four times, without regeneration, to give a consistent quality product. The aqueous solution of resulting LWCS exhibited a pH of 6.03±0.11, as against the acidic pH range of solutions of commercially available LWCS, indicating its suitability for biomedical applications. Our investigation facilitates a 'green approach' that may be employed for commercial production of value added chemicals from waste products of marine industry.
低分子量壳聚糖（LWCS）构成了一类特殊的增值化学品，主要从甲壳类动物的壳中获得，这些壳是螃蟹和虾加工中心的主要水污染物。与壳聚糖不同，LWCS在水中和水溶液中的溶解度提高，使其在从药物输送到废水处理的众多领域中得到广泛应用。在其生产中采用的方法中，通过强液体酸的化学分解已取得了很好的成功。但是，这种方法存在严重的问题，因为液体酸的性质苛刻，可能会腐蚀商业合成用的反应器，并且其可重复使用性有限。物理方法，如超声和微波，在性质上是能量密集的，而酶方法既昂贵又提供的重复使用范围有限。我们试图通过使用基于碳的固体酸（CSA）来水解壳聚糖来克服这些问题。CSA 可以使用活性炭很容易地生产，活性炭是一种具有成本效益且易于获得的原料。在水热玻璃反应器中，壳聚糖和 CSA 之间进行反应，通过冷离心分离出产物，然后对产物进行纯化和干燥。对干燥产物的分子量和溶解度进行了表征。结果表明，壳聚糖的分子量降低了十倍以上，并且产物具有水溶性。CSA 可以在不进行再生的情况下使用多达四次，以提供一致质量的产品。所得 LWCS 的水溶液的 pH 值为 6.03±0.11，而市售 LWCS 溶液的 pH 值在酸性范围内，表明其适用于生物医学应用。我们的研究促进了一种“绿色方法”，可以从海洋工业的废物中用于商业生产增值化学品。
