Novel distance dependence of diffusion constants in hyaluronan aqueous solution resulting from its characteristic nano-microstructure

Material transports in hyaluronan (HA) aqueous solution were investigated a pplying two different techniques, i.e., pulsed field gradient NMR (PFG-NMR) and photochemical quenching, to the measurement of diffusion constants to show a sharp contrast resulting from the difference of the spectroscopic ob servation time while the same probe molecules were commonly used in two exp eriments. The value from PFG-NMR reflects the relatively long transport alo ng which the majority of the molecules are retarded by the mesh structure o f HA solution. In such inhomogeneous fluids, the observable diffusion const ant should generally depend on the observation time and, i.e., the averaged distance of diffusion. Quantitative discussion, which compares the obtaine d characteristic distance of diffusion with the pore size, clarifies the ro le of the nano-microstructure of HA solution forming small pores surrounded by the polymer chain networks.