IMAGING POLYSACCHARIDES BY ATOMIC-FORCE MICROSCOPY

Techniques have been developed for the routine reliable imaging of pol ysaccharides by atomic force microscopy (AFM). The polysaccharides are deposited from aqueous solution onto the surface of freshly cleaved m ica, air dried, and then imaged under alcohols. The rationale behind t he development of the methodology is described and data is presented f or the bacterial polysaccharides xanthan, acetan, and the plant polysa ccharides iota-carrageenan and pectin. Studies on uncoated polysacchar ides have demonstrated the improved resolution achievable when compare d to more traditional metal-coated samples or replicas. For acetan the present methodology, has permitted imaging of the helical structure. Finally, in addition to data obtained on individual polysaccharides, A FM images have also been obtained of the network structures formed by kappa-carrageenan and gellan gum. (C) 1996 John Wiley & Sons, Inc.