Abstract: The invention provides a method of modifying soluble xylan which contains glucuronic acid and/or arabinose side chains so that it can be adsorbed onto other substrates. The method includes the steps of enzymatically modifying the xylan by selectively removing glucuronic acid and/or arabinose side chains from the xylan with ?-D-glucuronidase and/or ?-L-arabinofuranosidase, and allowing the modified xylan to adsorb onto the substrate. The substrate may be a cellulosic substrate like pulp or paper or a non-cellulosic substrate. The enzymes are able to remove a sufficient number of the xylan side chains so as to decrease water solubility of the xylan, induce xylan precipitation and allow adsorption of the xylan onto other substrates. A pulping process which incorporates modification of xylan and adsorption onto cellulosic material is also provided, as are products which contain the modified xylan.

Abstract: The invention provides a method of enzymatically modifying xylan by selectively removing glucuronic acid and/or arabinose side chains from the xylan with a-D-glucuronidase and/or a-L-arabinofuranosidase, and allowing the modified xylan to form into a hydrogel when the xylan becomes insoluble. A bioactive substance, such as a protein, enzyme, antimicrobial agent, bactericide or pharmaceutical compound can be added to the xylan so that the substance is encapsulated within the hydrogel or incorporated onto its surface. The hydrogel can be used as a drug delivery agent, such as for sustained-release or targeted drug delivery, rectal drug delivery or a dressing for a wound, burn or scar. The hydrogel can also be used as a coating, such as on medical gloves, catheters, surgical drainage systems, utensils or the like, or can be used in a scaffold for tissue engineering.