Anti-Biofilm Activity of Chiral Graphene Nanoparticles

The ability of bacteria to form complex structures called biofilms create numerous human health and industrial problems. These protective biological composites based on nanofibers are self-assembled from of amyloid peptides and other extracellular polymeric substances (EPS) secreted by bacterial cells. The current strategies for mitigating biofilms include inhibition of EPS production or fibrillation of EPS using small organic molecules or complementary peptides but they are subject to enzymatic degradation. Nanoparticles (NPs) are a promising new class of anti-biofilm agents for their highly tunable physical and chemical properties, stability, and ability to interact with biological molecules, namely proteins. Here, we report the anti-biofilm activity of L-cysteine or D-cysteine derived chiral graphene NPs (L/D-GNPs) against amyloid- rich Staphylococcus aureus (S. aureus) biofilms. Both enantiomers are capable of biofilm disruption. Notably, D-GNPs displayed higher affinity for amyloid fibers causing increased biofilm dispersal compared to L-GNPs. Chiral GNPs mimic peptide binding proteins, interfering with the self-assembly phenol soluble modulins (PSMs) , the monomeric form of amyloid fibers responsible for biofilm structuring and multiple other virulence factors. The effect of chiral GNPs on key PSM functions including cytolysis, IL-8 production, and anti-biofilm properties were also explored. The chiral interactions between GNPs and biofilm components give rise to a highly tunable anti-biofilm NP platform.