Antimicrobial resistance has become a worldwide issue,
with multiresistant
bacterial strains emerging at an alarming rate. Multivalent antimicrobial
polymer architectures such as bottle brush or star polymers have shown
great potential, as they could lead to enhanced binding and interaction
with the bacterial cell membrane. In this study, a library of amphiphilic
star copolymers and their linear copolymer equivalents, based on acrylamide
monomers, were synthesized via RAFT polymerization. Their monomer
distribution and molecular weight were varied. Subsequently, their
antimicrobial activity toward a Gram-negative bacterium (Pseudomonas aeruginosaPA14) and a Gram-positive
bacterium (Staphylococcus aureusUSA300)
and their hemocompatibility were investigated. The statistical star
copolymer, S-SP25, showed an improved antimicrobial activity compared
to its linear equivalent againstP. aeruginosaPA14. The star architecture enhanced its antimicrobial activity,
causing bacterial cell aggregation, as revealed via electron microscopy.
However, it also induced increased red blood cell aggregation compared
to its linear equivalents. Changing/shifting the position of the cationic
block to the core of the structure prevents the cell aggregation effect
while maintaining a potent antimicrobial activity for the smallest
star copolymer. Finally, this compound showed antibiofilm properties
against a robustin vitrobiofilm model.