Preparation of antimicrobial sodium alginate with chito-oligosaccharide side chains

To provide sodium alginate (SA) with an antimicrobial property, we introduced chito-oligosaccharide (COS) via chemical bonding in a two-step procedure. We reacted COS with N-methylol acrylamide (NMA) with N-methylol groups to prepare acrylamidomethyl chito-oligosaccharide (COS-NMA). SA with COS side chains (SACOS) was produced through a subsequent reaction of SA with COS-NMA. The chemical structure of SA-COS was confirmed by IR spectroscopy and ¹H NMR spectroscopy. With a two-step method, we successfully prevented insoluble-complex formation due to electrostatic attraction between chitosan and alginate. SA-COS showed excellent antimicrobial activity, with the growth of microorganisms completely suppressed by a small amount of COS (1.8 wt %).