Immobilisation on polystyrene of diazirine derivatives of mono- and disaccharides: Biological activities of modified surfaces

The potential of surface glycoengineering for biomaterials and biosensors o riginates from the importance of carbohydrate-protein interactions in biolo gical systems. The strategy employed here utilises carbene generated by ill umination of diazirine to achieve covalent bonding of carbohydrates. Here, we describe the synthesis of an aryl diazirine containing a disaccharide (l actose). Surface analysis techniques [X-ray photoelectron spectroscopy (XPS ) and time of flight secondary ion mass spectroscopy (ToF-SIMS)] demonstrat e its successful surface immobilisation on polystyrene (PS). Results are co mpared to those previously obtained with an aryl diazirine containing a mon osaccharide (galactose). The biological activity of galactose- or lactose-m odified PS samples is studied using rat hepatocytes, Allo A lectin and soli d-phase semi-synthesis with alpha -2,6-sialyltransferase. Allo A shows some binding to galactose-modified PS but none to lactose-modified surfaces. Si milar results are obtained with rat hepatocytes. In contrast, sialylation o f lactose-modified PS is achieved but not with galactose-modified surfaces. The different responses indicate that the biological activity depends not only on the carbohydrate per se but also on the structure and length of the spacer. (C) 2001 Elsevier Science Ltd. All rights reserved.