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

The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. . https://doi.org/10.1101/550285 doi: bioRxiv preprint To verify this point, structural change in PSMα1 peptides interacting with GQDs were monitored for conformational conversion on Day 4 and Day 9 of incubation using CD spectrometry. As previously observed, there are two stages of conformational and morphological changes of peptide aggregation for PSM amyloid-like fibrils. Initially, the freshly dissolved PSMα1 peptides mainly contain α-helixes. 43 The typical β-sheet signal with a negative band at ≈ 218 nm, 37 appears after four days for PSMα1 without GQDs (Figure 4a) . This suggested that formation of amyloid fibrils, which agreed with the result of ThT staining ( Figure S4) . Interestingly, secondary structures of PSMα1 incubated with GQDs showed enhancement of β-turns signal with a positive band at ≈208nm, in agreement with the theoretical peak of pure β-turns signal. 44, 45 Meanwhile, a broad peak from 250 nm and 375 nm was observed, corresponding to the absorption of GQDs onto peptide ( Figure S5) and associated with the deformed (coiled) conformation of the graphene sheet. 15 The combination of these two positive CD peaks of PSMα1 induced by GQDs in the All rights reserved. No reuse allowed without permission.