Microencapsulation of LL-37 Antimicrobial Peptide in PLGA

El Abbouni, Sarah

Etd

Microencapsulation of LL-37 Antimicrobial Peptide in PLGA

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Antimicrobial peptides are key actors in organismsÂ’ immune systems. They play an important role in phagocytosis, breaking bacteria membranes. They destroy the microbes, keeping them from repairing themselves, and therefore do not promote antimicrobial resistance. LL37 is a peptide produced by the human body. It is a short amino acid chain that is particularly active on the skin and mucous membranes. It has antimicrobial and fungal activity as well as wound healing properties, which makes it a very interesting active substance in wound treatment. However, its fragile and sensitive structure is a challenge to its use. Nowadays, encapsulation in a biocompatible polymer system is a promising technique in drug delivery, and presents a solution to LL37 administration and delivery. LL37 is a hydrophilic active substance, it will be trapped in PLGA (poly (lactic-co-glycolic acid)) by double emulsion and the microspheres will be shaped and stabilized by solvent evaporation. The capsules will be characterized by Dynamic Light Scattering (DLS) and Scanning Electron Microscopy. Their main features, drug loading, encapsulation efficiency and release profile, are determined using the Bradford assay. Since the peptide is expensive and delicate, it is important to optimize its encapsulation. For that reason, we will adapt the process to have the best drug loading as possible using water in oil in oil emulsions. For an external use, the capsules would be used over a few days, so having a fast release is very relevant. The larger the specific surface area, the faster the diffusion. For that reason, we will also study the impact of porosity on the release profile. As a result, different types of capsules will be synthesized, with higher porosity and by two processes: aqueous double emulsion and oil double emulsion. Their characteristic features and impact on bacterial pathogens will be determined and compared in order to determine their optimal synthesis process and formulation in given conditions of use.

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