Control of the graphene-protein interface is required to preserve adsorbed protein function.
Graphene's suite of useful properties makes it of interest for use in biosensors. However, graphene interacts strongly with hydrophobic components of biomolecules, potentially altering their conformation and disrupting their biological activity. We have immobilized the protein Concanavalin A onto a self-assembled monolayer of multivalent tripodal molecules on single-layer graphene. We used a quartz crystal microbalance (QCM) to show that tripod-bound Concanavalin A retains its affinity for polysaccharides containing α-D-glucopyrannosyl groups as well as for the α-D-mannopyranosyl groups located on the cell wall of Bacillus subtilis. QCM measurements on unfunctionalized graphene indicate that adsorption of Concanavalin A onto graphene is accompanied by near-complete loss of these functions, suggesting that interactions with the graphene surface induce deleterious structural changes to the protein. Given that Concanavalin A's tertiary structure is thought to be relatively robust, these results suggest that other proteins might also be denatured upon adsorption onto graphene, such that the graphene-biomolecule interface must be considered carefully. Multivalent tripodal binding groups address this challenge by anchoring proteins without loss of function and without disrupting graphene's desirable electronic structure.
School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States. ta232@cornell.edu
Thomas
T
Alava
Jason A
JA
Mann
Cécile
C
Théodore
Jaime J
JJ
Benitez
William R
WR
Dichtel
Jeevak M
JM
Parpia
Harold G
HG
Craighead
D000327:Adsorption; D001412:Bacillus subtilis / Q000166:cytology; D032449:Canavalia / Q000737:chemistry; D002473:Cell Wall / Q000378:metabolism; D018914:Cells, Immobilized / Q000378:metabolism; D003208:Concanavalin A / Q000737:chemistry* / Q000378:metabolism*; D006108:Graphite / Q000737:chemistry*; D008070:Lipopolysaccharides / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism*; D013682:Teichoic Acids / Q000378:metabolism
D008070:Lipopolysaccharides; D010940:Plant Proteins; D013682:Teichoic Acids; D003208:Concanavalin A; C009900:lipoteichoic acid; D006108:Graphite