Double membrane based on lidocaine-coated polymyxin-alginate nanoparticles for wound healing: In vitro characterization and in vivo tissue repair.

The aim of this study was to develop and characterize a double layer biomembrane for dual drug delivery to be used for the treatment of wounds. The membrane was composed of chitosan, hydroxypropyl methylcellulose and lidocaine chloride (anesthetic drug) in the first layer, and of sodium alginate-polymyxin B sulphate (antibiotic) nanoparticles as the second layer. A product with excellent thickness (0.01-0.02 mm), adequate mechanical properties with respect to elasticity, stiffness, tension, and compatible pH for lesion application has been successfully obtained. The incorporation of the drugs was confirmed analysing the membrane cross-sections by scanning electron microscopy. A strong interaction between the drugs and the functional groups of respective polymers was confirmed by Fourier-Transform Infrared Spectroscopy, thermal analysis and X-ray diffraction. Microbiological assays showed a high antimicrobial activity when polymyxin B was present to act against the Staphylococcus aureus and Pseudomonas aeruginosa strains. Low cytotoxicity observed in a cell viability colorimetric assay and SEM analysis suggest biocompatibility between the developed biomembrane and the cell culture. The in vivo assay allowed visualizing the healing potential by calculating the wound retraction index and by histological analysis. Our results confirm the effectiveness of the developed innovative biomaterial for tissue repair and regeneration in an animal model.

Antibacterial activity of chitosan/collagen membranes containing red propolis extract.

In this study we developed a mucoadhesive polymeric membrane wound dressing incorporating red propolis extract (HERP). Membranes were made using a casting method employing collagen, chitosan, polyethylene glycol (15, 20, and 30v%), and hydroethanolic extract of EtOH-H2O 70v% - 30v% (v/v) of HERP (0.5, 1.0, and 1.5%). Membranes were extensively characterized to assess the thickness, pH, morphology using Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), mechanical properties, swelling, in vitro mucoadhesion, cytotoxicity, and minimum inhibitory concentration (MIC). Assessment of the thickness and mechanical properties of the membranes containing HERP revealed that the most significant thickness obtained was 40.7 µm; thermal analysis suggests suggesting the hydrogen bonds between hydroxyl groups of isoflavones and the free amine present in the region of chitosan. Cell viability decreased as the amount of HERP increased. Finally, the MICs were 7.8 and 1.9 µg.mL-1 for Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853, respectively. These results were suggesting that the 0.5 % HERP membrane has the potential for future studies for wound application.