Devices such as contact lenses and collagen shields have been used to improve the antibiotic bioavailability of eye drops formulations in the treatment of ulcerative keratitis. Nevertheless, these devices are not sustained drug delivery systems, and a combination with eye drops is necessary. In animal patients, it requires constant supervision by trained personnel to avoid device loss, which increases the cost of treatment. In this study, PVA/anionic collagen membranes containing ciprofloxacin or tobramycin were prepared using two different methodologies, and the release, physical and antimicrobial properties were evaluated. The membrane containing ciprofloxacin was selected as a sustained drug delivery system with antibacterial activity against Staphylococcus aureus and Escherichia coli during 48 h. Despite to be opaque, due to its heterogeneous morphology, this membrane had the adequate mechanical strength, water content, hydrophilicity, water vapor permeability, and surface pH to interact with cornea without causing discomfort. In the surface of this membrane it was observed dispersed collagen fibrils which could serve as a substrate for corneal proteinases, contributing to the reduction in stromal damage and enhancing the epithelium regeneration. These results encourage the idea these membranes are new cost-effective and safe alternatives to treat corneal ulcers in animal patients.

DAZA, Jorge Humberto Unás. Development of PVA/Anionic Collagen membranes as new polymeric controlled drug-delivery systems of antibiotics. 2019. 113 f.

Biosurfactants (BS) are microbial-derived molecules showing tensoactive and emulsification properties. These compounds are candidates to replace synthetic surfactants for industrial applications due to their less toxicity, greater biodegradation capacity, greater chemical diversity and greater efficiency and effectiveness under extreme physical conditions of salinity, pressure and temperature. Commercial and industrial use of BS is not sustainable due their high production cost mainly related to low production yields. The use of low cost substrates and statistical tools to enhance the production yield of biosurfactants are two of the main strategies to deal with that problem. The objective of this work was to study the production and recovery of the BS produced by B. luteolum, aiming to enhance its production through a factorial experimental design, and to characterize the chemical structure of the BS. It was found that resin adsorption was more effective than acid precipitation to recover the BS. The production of BS was enhanced through a factorial experimental design 2 3 using the concentrations of the carbon source (mineral oil), the nitrogen source (ammonium nitrate) and artificial seawater as the factors and the surface tension of a solution 0,1% of BS as the response. The value of factors that enhanced the production of BS were 4% of carbon source, 2% of nitrogen source and 20% of artificial sea water showing a surface tension of 27mNm -1. The BS was characterized as a mix of lipopeptides with fatty acid chains varying between 10-18 carbon units and a total protein content of 5%. Three chemical structures were proposed for the active compounds: two proline-lipids with the fatty acid chains C 16:0 e C 18:0 respectively and a lipopeptide with a peptide sequence Phe-Al-X-X-Pro-Pro-Thr (X=Leu/Ile) linked to a fatty acid chain C 16:0 . BS did not show antimicrobial activity against S. aureus, E. coli, S. enteritidis, L. monocytogenes and S. mutans at concentration range tested. The use of mineral oil as a substrate for the production of the BS suggests that the bacteria and the BS can be explore for applications as bioremediation and enhanced oil recovery (EOR).