Molecular recognition capability and rheological behavior in solution of novel lactone-based glycopolymers M.L. Cerrada, C. Ruiz, M. Sánchez-Chaves, M. Fernández-García * Instituto de Ciencia y Tecnología de Polímeros (CSIC), C/Juan de la Cierva 3, 28006 Madrid, Spain article info Article history: Received 8 May 2009 Received in revised form 24 July 2009 Accepted 31 July 2009 Available online 12 August 2009 Keywords: Glycopolymers EVOH Modification Lectins Recognition Rheological response abstract Novel glycopolymers have been prepared from ethylene–vinyl alcohol copolymers, EVOH. For that purpose, three distinct aminosaccharides (N-(4-aminobutyl)-D-gluconamide (NABG), N-(4-aminobutyl)-O-b-D-galactopyranosyl-(1 ? 4)-D-gluconamide (NABL) and N-(4-aminobutyl)-O-b-D-glucopyranosyl-(1 ? 4)-D-gluconamide (NABM) have been syn- thesized. The previous functionalization of these EVOH copolymers is mandatory to acti- vate their hydroxyl reactivity before the subsequent coupling reaction with the aminosaccharides. The activation with carboxylic acid groups by reaction with phthalic anhydride has been chosen in the current investigation because of its almost quantitative yield and the subsequent high modification extent reached (>60%). The glycopolymers that turned out water-soluble (i.e., those based on NABL and NABM) have shown a reversible network formation unusually described in glycopolymers. In addition, their capability to interact with lectins, particularly Concanavalin A and Ricinus communis Agglutinin, has confirmed the specificity of lectin recognition in these glycopolymers. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Glycopolymers as synthetic macromolecules featuring pendant carbohydrate moieties have received much atten- tion [1–3], because of their promising biological and bio- medical applications [4–9]. This kind of polymers can play a decisive role in molecular recognition processes since they reveal strong interactions with lectins through the saccharide moieties in the so-named glyco-cluster effect [10–12]. This interaction can be interrupted when high concentration of small saccharide exists in the med- ium [13–18]. Therefore, the development of suitable and simple synthetic methods to incorporate key sugar units to polymers is nowadays of great importance. The better scenario is to obtain glycopolymers that exhibit the excel- lent properties inherent to their polymeric nature as well as these commented molecular recognition characteristics. The synthesis of saccharide-containing polymers with well-defined structure is usually performed by two meth- ods: (a) the polymerization or copolymerization of sugar bearing monomers by conventional or controlled polymer- ization techniques [19–31] and (b) the chemical modifica- tion of an appropriate macromolecular carrier with a saccharide-containing reagent [32–41]. In these two meth- odologies, the sugar is attached to the polymer by ester, amide, carbamate, ether linkages among others. It is important to avoid, if possible, undesirable sugar protect- ing/deprotecting processes [42–46] because these multi- step reactions make tedious the synthetic protocol in addition to reduce the overall yield. On the other hand, ethylene–vinyl alcohol copolymers, EVOH, with vinyl alcohol content higher than 55 mol %, are a unique type of polymers since they exhibit good blood compatibility and excellent barrier properties as poly(vinyl alcohol) (PVOH) homopolymer but much better processability. These characteristics make them suitable for food packaging films, especially for those that are sensitive to certain levels of oxygen or carbon dioxide, and allow using them as membranes [47–56] in blood purification devices, including hemodialyzers and plasma- pheresis. Therefore, these copolymers are excellent 0014-3057/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2009.07.022 * Corresponding author. Tel.: +34 915622900; fax: +34 915644853. E-mail address: martafg@ictp.csic.es (M. Fernández-García). European Polymer Journal 45 (2009) 3176–3186 Contents lists available at ScienceDirect European Polymer Journal journal homepage: www.elsevier.com/locate/europolj