Figure 1A.  See [
Toole, BP, Turner, RE, Banerjee SD. Hyaluronan-Binding Protein in chondrogenesis and angiogenesis, 1993.] After my doctoral research on the molecular weight dependency of hyaluronic acid (HA) on physical properties, I wanted to show that there was also an HA size dependency on chrondrogenesis and angiogenesis during chick embryonic limb development. 

An Overview 

My dissertation involved the biophysical characterization of low molecular weight fragments (segments) of hyaluronic acid (HA) also known as hyaluronan. Basically, the model in figure 2 was proposed. This model led to a further study on the role HA size plays in tissue matrix engineering. . In Toole's group, I was able to study how HA size affects tissue engineering. [8][9][10]

Fig. 2. Model for self-association of HA segments in 0.15 NaCl, as a function of segment chain length (number of repeating disaccharide units). This model was proposed and validated. The importance of segment size in the intact cell should not be underestimated. The enzymes used to stitch and un-stitch HA segments are key to engineering the matrix of living creatures. The cellular biology results confirmed what was expected based on the solution work. However, what is the driving force for self-assembly beyond the biophysical properties?

After a long hiatus from research, I was invited to the Center for Materials Science and Engineering at MIT from 2006-2008. While there, I examined the size dependency of HA matrix properties on glass surfaces after dehydration from aqueous solution. Purified segments of HA, which I prepared, and those not prepared by my hands formed hierarchical patterning resembling different biological tissue matrices. Analytic techniques such as TM AFM, IR/UV, TEM, SEM, LEXT 3D Laser Microscopy, Phase Contrast Microscopy, and layer-by-layer techniques were used to characterize dehydrating HA fragments. Details of this research were copyrighted in 2008 as MIT Lab Notes.

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