Anti-biofilm Activity of Graphene Quantum Dots via Self-Assembly with Bacterial Amyloid Proteins

Abstract

Bacterial biofilms represent an essential part of Earth's ecosystem that can cause multiple ecological, technological and health problems. The environmental resilience and sophisticated organization of biofilms are enabled by the extracellular matrix that creates a protective network of biomolecules around the bacterial community. Current anti-biofilm agents can interfere with extracellular matrix production but, being based on small molecules, are degraded by bacteria and rapidly diffuse away from biofilms. Both factors severely reduce their efficacy, while their toxicity to higher organisms create additional barriers to their practicality. In this paper we report on the ability of graphene quantum dots to effectively disperse mature Staphylococcus aureus biofilms, interfering with the self-assembly of amyloid fibers -a key structural component of the extracellular matrix. Mimicking peptide-binding biomolecules, graphene quantum dots form supramolecular complexes with phenol soluble modulins, the peptide monomers of amyloid fibers. Experimental and computational results show that graphene quantum dots efficiently dock near the N-terminus of the peptide and change the secondary structure of phenol soluble modulins, which disrupts their fibrillation and represents a novel strategy for mitigation of bacterial communities.

From proteins to nanoparticles: domain-agnostic predictions of nanoscale interactions

“…Finally, by analyzing the predictions for individual amino acids (Fig. 4c), we also confirm the importance of the N-terminal residues (which have the highest interaction probability), likely due to the GQD's negative charge (dissociated carboxylic groups), in agreement with the previous observations by Wang et al [51]. Of note, these conclusions are not dependent overall on the specific definition of contact time, and hold even when different definitions are used (Supplementary Information, section 5).…”

Ångstrom-scale silver particle–embedded carbomer gel promotes wound healing by inhibiting bacterial colonization and inflammation

“…Considering the important role of bacteria and their endotoxins in triggering inflammation in the wound sites (6), we hypothesized that the bacterial killing activity of L-AgÅPs-gel may contribute importantly to the anti-inflammatory effects of L-AgÅPs-gel. Biofilm formation protects bacteria against environmental threats such as antibiotics and host immune defenses (37) and has been considered as an important reason for prolonged inflammation and impaired wound healing (38). L-AgÅPs-gel caused much higher levels of inhibition and destruction of biofilm compared with AgNPs-gel, which may be another critical factor that leads to the stronger anti-inflammatory and pro-wound healing activities of L-AgÅPs-gel.…”

Recent advances of carbon dots as new antimicrobial agents

“…35,36 Alternately, CDs were enriched with the bacterial wall/membrane, and may infiltrate bacteria and inhibit the formation of bacterial biofilms, leading to the cellular cytoplasm leakage and apoptosis of bacteria. 37,38 CDs can also penetrate bacterial walls and membranes and bind to DNA and RNA in bacteria and fungi via noncovalent interactions, changing the structure of DNA (secondary conformations) and RNA, causing the DNA double-helix to separate. Finally, the bacteria growth is affected by many factors to achieve an antimicrobial effect.…”

“…Electrostatic effects lead to biological isolation from growing bacteria, preventing bacteria from spreading or consuming nutrients and disturbing their physiological metabolism 35,36 . Alternately, CDs were enriched with the bacterial wall/membrane, and may infiltrate bacteria and inhibit the formation of bacterial biofilms, leading to the cellular cytoplasm leakage and apoptosis of bacteria 37,38 . CDs can also penetrate bacterial walls and membranes and bind to DNA and RNA in bacteria and fungi via noncovalent interactions, changing the structure of DNA (secondary conformations) and RNA, causing the DNA double‐helix to separate.…”