ANTIMICROBIAL PEPTIDES: A NOVEL WAY TO COMPREHEND ITS INDIVIDUAL MECHANICAL PROPERTIES IN CONTACT WITH ARTIFICIAL MEMBRANES

The mechanical properties of cells and biomimetic systems, such as giant unilamellar vesicles (GUVs), are indicators of cellular characteristics, cytoskeletal composition, and phospholipid membrane organization. Antimicrobial peptides (AMPs), such as BP100, interact with the membrane surface, locally altering its physicochemical properties. The discovery of antibiotics has saved millions of lives; however, their unrestricted use has resulted in the selection of resistant bacteria, a growing threat that reduces the effectiveness of these drugs. In this scenario, AMPs emerge as a promising alternative to combat bacterial infections. BP100, a short-chain peptide with a net positive charge, preferentially interacts with the surface of bacterial membranes, which are typically anionic. After adsorption, it inserts itself into the lipid bilayer, destabilizing the structure and leading to membrane disruption. This project aims to investigate the interaction between the BP100 peptide and membrane models through methods such as insertion into monolayers of selected composition, measuring the surface pressure with a Langmuir-Blodgett trough, and GUVs, which mimic bacterial surfaces. To this end, the optical tweezers technique will be used to extract membrane tethers. In this technique, polystyrene microspheres functionalized with the peptide will be captured by a laser beam and brought close to the GUV to interact with the membrane and extract a tether. The force required to maintain this tether will be measured. The presence of the peptides on the microsphere is expected to alter the mechanical properties of the membrane, resulting in changes in the measured force parameters when compared to control experiments with uncoated microspheres. With a view to future clinical applications, the same methodology will be applied to eukaryotic cells, specifically erythrocytes. This study will allow us to evaluate the cytotoxicity of BP100 in a human cell model and elucidate the selectivity of its interaction by comparing the effects on two distinct membrane surfaces: bacterial and eukaryotic.