ABSTRACT
There are more than 200 known genera of diatoms and as many as 200,000 species, living in oceans, freshwater, and in the soil. The majority of species are found in the oceans where they are major contributors to oxygen generation via photosynthesis, and are the basis of the food chain for numerous marine and fresh water species (Hasle and Syvertsen 1997). Some diatoms produce a nanofi ber component consisting of a high molecular weight polysaccharide. The nanofi bers include many individual polymers aligned in parallel and tightly hydrogen-bonded resulting in a unique three dimensional structure. These fi bers have been visualized and characterized by electron microscopy. Figure 1A shows a high resolution (250,000X) electron micrograph of a dried membrane “patch” of these nanofi bers. The individual pGlcNAc nanofi bers have widths within the 0.1µ range. It is this “patch” that is used as described below in cutaneous wound healing. Figures 1B and 1C show the nanofi bers and sub-fi bers contained within and dimensions of both the nanofi bers and their associated sub-fi ber structures. Chemical analyses have shown that these nanofi bers consist of long chains of N-acetyl glucosamine in a β1-4 linkage (Fig. 2). As measured using intrinsic viscosity, the nanofi bers consist of high molecular weight fully acetylated pGlcNAc polymers averaging molecular weight of 2.8 X 106 Daltons and containing 80 to 120 pGlcNAc polymers per nanofi ber. Figure 3 shows an infrared spectrum (FTIR) of the
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pGlcNAc nanofi bers indicating their unique covalent chemical structure while X-ray scattering studies show they are organized in a unique beta quaternary structure. This unique 3D structure is the basis for their many biological activities.
