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

To confirm the change of secondary structure in protein, we monitored PSMα1 fibrillation with or without GQDs using attenuated total reflectance -Fourier transform infrared spectroscopy (ATR-FTIR) (Figure 4c, d) . Deconvolution of the absorbance spectra in the amide I region 46 is indicative of the individual secondary structure components and their relative contribution to the main signal. PSMα1 peptides incubated with or without addition of GQDs for four days display common bands both at ≈ 1655 cm -1 and ≈ 1677 cm −1 . The peak at 1655 cm -1 corresponds to α-helix which appears between 1650 cm -1 and 1657cm -1 and overlapped with turns between 1655 cm −1 and 1675 cm −1 . The latter is attributed to the weak peak of antiparallel β-sheet structure 1670-1690 cm -1 . With addition of GQDs, antiparallel β-sheet were significantly decreased and indicated the inhibition of amyloid fibrillation at early stage of fibril growth. Meanwhile, the band at ≈ 1655 cm −1 right-shifted and became narrower, which verified the slight changes from α-helix to β-turns in PSMα1 dispersion. After 9 days, the α-helix peak decreased in all samples. At the same time, All rights reserved. No reuse allowed without permission.