Collagen-doxycycline matrices crosslinked with a natural polyphenol -tannic acid for the treatment of infected wounds were obtained by the freeze-drying of the corresponding gels. FT-IR spectra show that the triple helical structure of collagen is preserved in all the matrices, doxycycline produce collagen crosslinking and the degree of crosslinking increases with tannic acid concentration. Digestion of matrices using collagenase confirms the crosslinking effect of doxycycline and tannic acid and the increasing of the crosslinking degree with the amount of acid. The release of doxycycline from the matrices crosslinked with tannic acid is slower than that from the uncrossliked one and decreases with increasing of acid concentration, according to FT-IR and digestion results, and follows the power law model, with a release exponent of about 0.4, which indicates an anomalous transport. The matrices containing doxycycline, tannic acid and their combination do not develop gram-positive (Staphylococcus aureus) or gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria, fungi or leavens.

We presented here the phase diagrams and the influence of the external electric field on the lyotropic liquid crystal phase (LLC) for some binary and pseudoternary systems based on surfactants. Binary systems are of the type surfactant/water (S/W) and the pseudoternary systems are of the type surfactant/oil/water (S/O/W). Two surfactants have been used: the lauryl alcohol ethoxilated with 11 molecules of ethylene oxide (LA11EO), which is a nonionic compound, and a mixture of LA11EO with the cationic surfactant named alkyl C 12– C 14-dimethyl-benzyl ammonium chloride. Based on these two types of surfactants, pseudoternary systems were prepared. Pine oil has been used as the oil. The region where the LLC phase appears depends on the concentration of the surfactant and that of the pine oil, respectively. It is strongly influenced by the nature of the surfactant and by the presence of the pine oil for the same type of surfactant. The influence of the external electric field, investigated by measuring the electric current appearing in the samples for different concentrations of surfactant and pine oil was found to be more important in the case of the systems based on the nonionic-cationic mixture of surfactants. The results are discussed in terms of a theoretical model based on the local thermal equilibrium approach for systems running nonstatic processes.