Qiang Li1

1, Shandong University, Jinan, , China

Noncovalent modification of graphene with biomolecules such as DNA/RNA, protein, peptides and others is a promising method for fabricating novel sensors with high biosensing performances on both sensitivity and selectivity. However, predicting and characterizing adsorbed biomolecules at graphitic interfaces raises substantial theoretical and experimental challenges.
In this presentation, I will introduce our recent results, which studies the structure of peptides and RNA molecules adsorbed on graphene and graphite interface by employing advanced atomic force microscopy (AFM) and molecular dynamics (MD) simulations.1,2 For amyloid peptide adsorbed on hydrophobic graphite interface, the early Aβ peptide aggregates forming the molecular monolayer are investigated. The Aβ peptide molecular monolayer consisting of novel parallel β strand like structure is further revealed by means of a AFM based quantitative nanomechanical spectroscopy technique with force controlled in pico Newton range, combining with MD simulation. The identified parallel β strand like structure of molecular monolayer on graphite interface is distinct from the antiparallel β strand structure of Aβ amyloid fibril.1 For RNA molecules adsorbed on graphene interface in water, the AFM results showed that the key parameters governing the RNA’s behavior on the graphene surface are the number of graphene layers, RNA concentration, and temperature. At high concentrations, the RNA forms a film on the graphene surface with entrapped nanobubbles. The density and the size of the bubbles depend on the number of graphene layers. At lower concentrations, unfolded RNA stacks on the graphene and forms molecular clusters on the surface.2 Our findings on the structure of biomolecules adsorbed on graphitic interfaces would facilitate new applications of graphene derivatives in biosensors and biotechnology.

[1] Identification of parallel β-stand conformation within molecular monolayer of amyloid peptide, Liu, L.†; Li, Q.†; Zhang, S†; Wang, X.F.;Hoffmann, S. V.; Li, J.Y.; Liu, Z.; Besenbacher, F.*; Dong, M.D.*, Advanced Science, 2016, 3, 1500369
[2] Tuning of RNA nanopatterning on graphene, Li, Q.; Froning, J.P.; Pykal, M.; Zhang, S.; Wang, Z.G.; Vondrák, M.; Banáš,P.; Čépe, K.; Jurečka P.; Šponer, J.; Zboril, R.; Dong, M.D.*; Otyepka, M.*
ACS Nano, 2017, under review,