(582b) Molecular Dynamics Simulations of Peptide-SWCNT Interactions: Role of Curvature

Direct electron transfer between the redox active prosthetic group, flavin adenine dinucleotide (FAD), of oxidoreductases and single-walled carbon nanotubes (SWCNT) results in generation 3 biosensors and advanced biofuel cells. Phage display has recently been used to identify a specific dodecapeptide sequence (HWKHPWGAWDTL) that has high affinity for SWCNTs. Using this adsorptive peptide sequence, analogous sequences that share some homology with key enzymes (Glucose oxidase (GOx), Lactate oxidase (LOx) and Laccase (Lac)) used in generation 3 biosensors and advanced enzyme biofuel cells were identified. These high affinity sequences were found to decorate the surfaces of these enzymes, being away from the redox-active co-factor that would otherwise allow direct electron transfer. Molecular dynamics simulations were performed to study the interactions of four discrete dodecapeptides, along with the original phase display dodecapeptide, with a suite of SWCNT of varying diameters (6,0 f=0.47nm; 10,0 f=0.78nm; 15,0 f=1.17nm and 16,0 f=1.25nm) and with graphene in explicit water. Simulations were done using GROMACS parameterized using AMBER for the peptides, OPLS for the SWCNTs and TIP4P for water. From the progression of the radius of gyration, R_g, the peptides studied were concertedly adsorbed to both the SWCNT and graphene. Peptide properties based on group contributions, such as hydrophobicity and solubility parameter, did not correlate with the observed adsorption behavior as quantified by R_g. The SWCNT diameter was found to influence the adsorption interaction.