*Xylan-Based Hydrogels: A Polymeric Carrier for Sustained and Targeted Delivery of Drugs DOI: http://dx.doi.org/10.5772/intechopen.109201*

algae, xylan additionally contains β-(1 → 3) linkages. The β-(1 → 4)-D-xylopyranose unit of xylan is randomly substituted by glycosyl and acetyl groups depending on the source of the feedstock and extraction method [7, 8]. Depending upon the extraction method such as non-alkaline and alkaline treatment, xylan can be classified as acetylated (xylopyranose unit is substituted with acetyl groups) and non-acetylated (without substitution). Thus isolation of xylan can either be done by alkaline treatment or non-alkaline treatment.

The isolation of xylan from agro-waste raw materials is depicted in **Figures 1** and **2**. To isolate the xylan, the raw materials were milled into powder with uniform size of narrow distribution by mechanical agitation. The powdered raw materials were dewaxed with a mixture of toluene and ethanol in a ratio of 2:1 (v/v) in Soxhlet extractors for 12 hours. The solvent-soluble non-volatile materials were removed during the extraction known as dewaxing or extractive free process. The dewaxed/extractive free raw materials were delignified either with acidified NaClO2 or with per acetic acid (PAA).
