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Hydrogels of uncrosslinked gelatin, crosslinked gelatin (Gelx), and various compositions of semi-interpenetrating polymer network of cross-linked gelatin with uncross-linked sodium carboxymethylcellulose [Gelx-NaCMC] were investigated as potential matrices for substrate delivery. Simultaneous swelling behavior and controlled drug release under enzymatic conditions (erodible) were monitored for hydrogels of [Gelx-NaCMC] and Gelx. Results indicated a first order release indicating that the processes (rate of drug diffusion and degradation) do not follow the same kinetics.

Full interpenetrating polymer networks (FIPNs) of cross-linked gelatin with polyacrylamide [Gelx-PAamx] and N-isopropylacrylamide [Gelx-PNIPAx] of several compositions were prepared, respectively. Their dynamic swelling studies as a function of temperature were monitored. The rate of swelling increased with the rise in ambient temperature for [Gelx-PAamx]. For [Gelx-NIPAx] with the increase in temperature above its LCST (lower critical solution temperature) (i.e., 32°C) decreased the swelling and below its LCST increased in swelling. From the Fickian equation, the transport mechanism for [Gelx-PAamx] was determined to be anomalous, and for [Gelx-PNIPAx] below its LCST is anomalous and above, is Fickian type of diffusion. The activation energies were determined from the initial rate of swelling, which were found to be positive for [Gelx-PAamx] ranging from 36 to 55 kcal/mol, whereas for [Gelx-PNIPAx], the values were negative ranging from –331 to –55 kcal/mol. The enthalpies for these FIPNS were also estim...

Hydrogels of gelatin crosslinked with glutaraldehyde and sodium carboxymethyl cellulose (NaCMC) of several compositions were prepared. The swelling kinetics as a function of composition, temperature. pH, and ionic strength was studied. The rate of swelling and equilibrium swelling were found to depend on the NaCMC content in all cases. The equilibrium swelling increased with the temperature. The gels, which were weakly acidic, registered increased swelling at higher pH. Swelling was suppressed in aqueous salt solutions. In agreement with predictions of the Donnan theory, swelling in monovalent salt solutions is greater than in divalent salt solutions.