Amino acids meet electronics
May 24, 2005
Scientists at Bell Labs in the US have measured how different amino acids adhere to the various types of materials that are used to make electronic devices. The 20 known amino acids are the basic building blocks of life and all the proteins in the body are made from them. The Bell Labs team then went on to design an inorganic nanostructure that was capable of selectively binding to a particular sequence of amino acids (Proc. Natl. Acad. Sci. to be published).
Bob Willett and colleagues studied how different peptides -- each of which contained between eight and ten amino acids -- adhered to different materials. These included five metals (gold, palladium, platinum, titanium and aluminium), two semiconductors (gallium arsenide and aluminium gallium arsenide) and two insulators (silicon nitride and silica).
The Bell Labs team found that, in general, peptides chains with side groups that had an electric charge adhered more strongly than those that were uncharged. The silica, silicon nitride and aluminium surfaces were generally more adherent than the gallium arsenide and palladium surfaces. Moreover, the non-oxidized metals -- platinum, palladium and gold -- interacted only weakly with amino acids.
The team then used their results to build an inorganic surface that was able to adhere to a particular peptide chain. The surface, which was made with molecular beam epitaxy, was created from a layered structure of gallium arsenide and aluminium gallium arsenide (AlGaAs) that was then etched to expose "veins" of AlGaAs. The thickness of the layers or veins was matched to a peptide sequence that contained Asp -- an amino acid that adheres to AlGaAs -- at its centre, surrounded on either side by Leu, which does not.
"Our results demonstrate a surprisingly large range of adhesion interactions," says Willett. "The adhesion maps are an empirical tool for attempting to understand certain molecular interactions with inorganic surface states and, perhaps more importantly, provide an empirical guide for building nanostructures that are hybrids of peptide-based materials and inorganics."
The team says its results could have applications in biomolecular detection and manipulation.
About the author
Liz Kalaugher is editor of nanotechweb.org