| Abstract
| - Methods previously developed for the atomic force microscopy (AFM)imaging of individualpolysaccharides (Kirby, A. R.; Gunning, A. P.; Morris, V. J.Biopolymers1996, 38, 355−366) havebeenextended in order to image networks and gels formed by the bacterialpolysaccharide gellan gum.Networks were formed by air-drying solutions of K+gellan onto freshly cleaved mica. AFM images wereobtained in the direct current contact mode at constant force underbutanol. Network formation can beinhibited by diluting the stock gellan solution or by convertingK+ gellan into the tetramethylammoniumsalt form. Inhibition of network formation led to AFM images ofheterogeneous populations of gellanaggregates (gel precursors). Attempts have been made to image thesurface of bulk aqueous gellan gelsunder butanol. The quality of the images obtained improved withincreasing gel modulus. For rigidacid-set gellan gels, molecular resolution was achieved, revealing abifurcated branched fibrous network.
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