Swelling behavior and controlled release of theophylline and sulfamethoxazole drugs in beta-lactoglobulin protein gels obtained by phase separation in water/ethanol mixture.

Physically cross-linked beta-lactoglobulin (BLG) protein gels containing theophylline and sulfamethoxazole low molecular weight drugs were prepared in 50% ethanol solution at pH 8 and two protein concentrations (6 and 7% (w/v)). Swelling behavior of cylindrical gels showed that, irrespective of the hydrated or dehydrated state of the gel, the rate of swelling was the highest in water. When the gels were exposed to water, they first showed a swelling phase in which their weight increased 3 and 30 times for hydrated and dehydrated gels, respectively, due to absorption of water, followed by a dissolution phase. The absorption of solvent was however considerably reduced when the gels were exposed to aqueous buffer solutions. The release behavior of both theophylline and sulfamethoxazole drugs from BLG gels was achieved in a time window ranging from 6 to 24 h. The drug release depended mainly on the solubility of the drugs and the physical state of the gel (hydrated or dry form). Analysis of drug release profiles using the model of Peppas showed that diffusion through hydrated gels was governed by a Fickian process whereas diffusion through dehydrated gels was governed partly by the swelling capacities of the gel but also by the structural rearrangements inside the network occurring during dehydration step. By a judicious selection of protein concentration, hydrated or dehydrated gel state, drug release may be modulated to be engineered suitable for pharmaceutical as well as cosmetics and food applications.

In situ polymerizable polyethyleneglycol containing polyesterpolyol acrylates for tissue sealant applications.

Polyesterpolyol macromers were prepared with succinic acid and polyethylene glycols (PEG) of different molecular weights. The resulting polyols were acrylated to render them photo-cross-linkable. They could be very rapidly cross-linked into non-tacky films with long-wavelength UV radiation. The resulting products were characterized by gel content, water equilibrium swell, cross-link density, Tg , tensile strength, degradation and in vitro burst strengths. Though all of them formed transparent contact lens like films, increasing the PEG molecular weight has resulted in polymers with higher hydrophilicity resulting in higher swelling, faster degradation, higher tensile strength, elongation at break and burst strength. Addition of vinyl pyrrolidinone as a reactive diluent has increased the mechanical as well as burst strength of the polymer. In vitro release of sulfamethoxazole entrapped in these cross-linked matrices was also studied.