Doctoral defence: Celia Teresa Pozo Ramos „Preparation and assessment of antimicrobial electrospun matrices for prospective applications in wound healing”

On May 10th Celia Teresa Pozo Ramos will defend her thesis „Preparation and assessment of antimicrobial electrospun matrices for prospective applications in wound healing”.

Supervisors:
Professor Karin Kogermann, University of Tartu
Professor Tanel Tenson, University of Tartu
Associate professor Ivo Laidmäe, University of Tartu
Visiting research fellow Marta Putrinš, University of Tartu

Opponent:
Professor Hanne Mørck Nielsen, University of Copenhagen (Denmark)

Summary:
Non-healing wounds constitute a significant burden to patients as well as to healthcare systems. Effective wound management is essential for controlling infections that occur when the skin barrier is compromised. Conventional topical formulations often face efficacy challenges due to their short residence time and the presence of wound exudate, while systemic antibiotics may raise toxicity concerns. Additionally, antimicrobial resistance poses a major challenge for treating wound infections, with the availability of effective drugs diminishing in recent years. This dissertation proposes novel drug delivery systems for local wound infection treatment, aiming to enhance the efficacy of antimicrobial substances.

Electrospun wound dressings, characterized by their nano- to microfibrous structure, enable the incorporation of active drug substances, thereby improving drug stability and controlling release rates. Additionally, electrospun matrices exhibit morphology and physicochemical properties that closely resemble the natural extracellular matrix, enhancing moisture balance, absorption, and gas exchange, thereby promoting wound healing.

The aim was to prepare and characterise antimicrobial electrospun fibrous matrices for use as wound dressings. Chloramphenicol and pleurocidin were separately incorporated into electrospun matrices using different polymers, solvent systems, and electrospinning techniques. Initially, porous fibers were developed, highlighting the crucial role of humidity and solvent in their preparation. Subsequent analyses of the morphology and mechanical properties of the electrospun matrices revealed significant influences from factors such as polymer concentration, fiber porosity, and solvent system. The electrospinning process affected the solid state of both the drug and polymer, inducing different molecular interactions and variations in the drug release profiles. The hydrophilicity/hydrophobicity ratio influenced release kinetics, while matrix morphology affected the wetting and buffer penetration abilities. The safety and biocompatibility of the matrices were confirmed through the MTS assay and confocal fluorescence microscopy. Antibacterial and antibiofilm properties against multiresistant wound pathogens varied based on the matrix morphology and drug release behaviour, with pleurocidin-loaded matrices notably outperforming freshly made solutions. Furthermore, the phenotypical effects of combining pleurocidin with different biocides revealed diverse outcomes that must be considered for concomitant treatment applications.