Covalent attachment of lysozyme to cotton/cellulose materials: protein verses solid support activation J. Vincent Edwards • Nicolette T. Prevost • Brian Condon • Alfred French Received: 3 March 2011 / Accepted: 2 June 2011 Ó Springer Science+Business Media B.V. (outside the USA) 2011 Abstract Covalent attachment of enzymes to cellu- losic materials like cotton is of interest where either release or loss of enzyme activity over time needs to be avoided. The covalent attachment of an enzyme to a cellulosic substrate requires either activation of a protein side chain or an organic functional group on the cellulosic substrate. Use of a water soluble carbodiimide to create an amide linkage as the covalent attachment between the enzyme and sub- strate represents an aqueous-based alternative which may be preferred for textile processes. Here we describe an amide bond-mediated lysozyme immobi- lization applied to cotton where either the carboxylate side chains of the protein or pendant carboxylates in a citrate, cross-linked cotton support are activated as the O-acyl-isourea intermediate, and the reactive amino nucleophiles are derived from amino-silanized cotton and the protein’s amino side chains, respectively. A comparison is made of the two activation approaches to covalently link lysozyme to two different cotton fabrics using the water soluble carbodiimide 1-cyclo- hexyl-3-(2-morpholinoethyl)-carbodiimide-metho-p- toluene sulfonate. A comparison of the resulting enzyme activities of lysozyme on two different cotton supports showed that linking lysozyme to citrate crosslinked cotton gave higher activity than on aminosilanized cotton. The lysozyme-cellulose con- jugate formed on the citrate crosslinked nonwoven cotton fabric gave the highest yield and antimicrobial activity. Keywords Lysozyme Á WSC carbodiimide Á Cotton Á Immobilization Introduction The increasing importance of pollution reduction in the textile industry along with energy and resource conservation has focused more attention to develop- ing sustainable, nontoxic applications using renew- able materials as alternatives to the conventional processes and material’s production. For example, synthetic processes involving the use of enzymes have generated more interest (Xie et al. 2009; Kotwal and Shankar 2009; Wang et al. 2009; Alonso et al. 2009). Cellulose-based fibers including viscose derived regenerated cellulose and a variety of natural fibers used in woven and non-woven materials are environmentally friendly and sustainable compared to most synthetic fibers. Among these natural cellulosic fibers, cotton which is used mostly in apparel and durable goods is an attractive option as a biocom- patible textile surface for biomedical and hygienic materials. Recent interest in creating cotton J. V. Edwards (&) Á N. T. Prevost Á B. Condon Á A. French Southern Regional Research Center, USDA-ARS, 1100 Robert E. Lee Blvd., New Orleans, LA 70124, USA e-mail: vince.edwards@ars.usda.gov 123 Cellulose DOI 10.1007/s10570-011-9563-6