The present invention relates to a polymer made of a primary amine functionalized polymer and a hemicellulose e.g. chitosan and xyloglucan, wherein the primary amine functionalized polymer is covalently bound to the hemicellulose, and to a cross-linking agent composition comprising the polymer. A method wherein manufacturing a cellulose containing product comprises the steps of providing a cellulose containing product treating said cellulose product with a cellulose adsorbing agent comprising a polymer made of a primary amine functionalized polymer and a hemicellulose e.g. chitosan and xyloglucan, and optionally other additives is also provided. Fig 1a
