UNITesi

Construction and use of medical devices for the selective removal of bacteria and endotoxins from biological fluids

CAPPELLO, GIOVANNI
2023
2023
Inglese
medical devices, antimicrobial peptides, sepsis, lipopolysaccharides, bacterial infection
The infections by multidrug-resistant (MDR) pathogens are steadily increasing and very often result in numerous cases of sepsis. For this reason, it is necessary to find not only new drugs active against these multidrug-resistant bacteria but also new strategies to counteract the evolution of sepsis. SET-M33 peptide is an antimicrobial peptide with a great ability to kill bacteria and bind bacterial wall components such as lipopolysaccharide (LPS) from Gram-negative bacteria and lipoteichoic acid (LTA) from Gram-positive bacteria. It is a cationic non-natural peptide synthetized in a tetra-branched form that makes it more resistant to degradation in biological fluids. SET-M33 peptide is characterized by high antimicrobial activity both in vitro and in vivo, anti-inflammatory capacity through neutralization of endotoxins such as LPS, low hemolytic activity, lack of immunogenicity, and is active against biofilm-forming bacteria. This paper reports the construction of a new device based on the antimicrobial peptide SET-M33 for the multiple and selective removal of both bacterial toxins (LPS and LTA) and live bacteria (Escherichia coli O111:B4 and Staphylococcus aureus USA 300) from biological fluids of patients in sepsis. The device was initially constructed by immobilizing the peptide on a resin constituted by agarose beads via a thiol residue at the c terminal of the peptide. Subsequently, the peptide was bound to a polyether sulfone (PES) resin by high-energy beta irradiation. In both cases, the devices demonstrated excellent retention of bacterial toxins and bacteria. For the preparation of the devices, the peptide was synthesized with amino acids in L configuration. The peptide to be bound to agarose beads was synthesized with a thiol residue at the c terminal end to allow thioether bonding with agarose resin, the peptide for PES matrix was prepared without any modification to the original structure as it was immobilized by exploiting radical formation due to high-energy beta irradiation. Stability studies and endotoxin removal (LPS) experiments in ex vivo animal models were also performed in this work. The safety of the devices was tested by electrophoretic analysis and hematochemical tests performed on pools of healthy and sepsis patients.
PINI, ALESSANDRO
Università degli Studi di Siena
105
Università degli Studi di Siena
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14242/88065
Il codice NBN di questa tesi è URN:NBN:IT:UNISI-88065