Transport of ions and molecules in biopolymeric gels: Electroanalytical studies

Transport of ions and molecules was studied in hydrogels of uncharged and anionic biopolymers, agarose, and i-carrageenan. Diffusion coefficients of neutral and ionic electroactive probes, the uncharged radical 2,2,6,6-tetramethyl-1-pipperidinyloxy, TEMPO, and T1(+), were determined rapidly and precisely from steady-state, transport-limited currents at platinum and mercury microelectrodes. Transport properties of both probes were studied in gels as affected by temperature, ionic strength, and concentration of the biopolymer, and they were compared with those in solutions. The relation between macroscopic and local microscopic viscosity of biopolymeric gels was analyzed based on viscosity measurements and diffusion coefficient data.