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

Yichun Wang; Usha Kadiyala; Zhibei Qu; Paolo Elvati; Christopher Altheim; Nicholas A. Kotov; Angela Violi; J. Scott VanEpps

These problems with the design of effective anti-biofilm agents prompted us to search for new materials platforms. Graphene quantum dots (GQDs) are a single layer graphene a few nanometers in diameter. They are often regarded as biocompatible alternatives of II-VI semiconductor NPs also known as quantum dots (QDs). 15 GQDs have been investigated for antibacterial activity due to reactive oxygen species production and membrane disruption. [16] [17] [18] While these functionalities highlight the significance of GQDs as a part of microbiology toolbox, we hypothesize that these nanoscale particles can interfere with the self-assembly processes of biomolecular components of the biofilms. Representing the common tendency of nanoscale particles to self-assemble, this hypothesis is grounded in the multiple observations of GQDs and other NPs to specifically interact and assemble with other nanoscale particles and biomolecules. [19] [20] [21] [22] [23] [24] [25] [26] [27] As applied to biofilms, GQDs can form 'decoy' complexes with the key structural components of ECM, thereby inhibiting the biofilm formation. Recently this functionality was confirmed by observation of GQDs acting as inhibitors of fibrillation of the protein characteristic for Alzheimer's and Parkinson's disease. [28] [29] [30] [31] Counteracting known problems of other anti-biofilm agents mentioned above, GQDs have high molecular weight (10 3 to 10 5 g/mol) that slows diffusion and are resistant to proteolytic degradation.