<p>Functional
integration of proteins with carbon-based nanomaterials such as nanotubes holds
great promise in emerging electronic and optoelectronic applications. Control over protein attachment
poses a major challenge for consistent and useful device fabrication,
especially when utilizing single/few molecule properties. Here, we exploit
genetically encoded phenyl azide photochemistry to define the direct covalent
attachment of three different proteins, including the fluorescent protein GFP, to
carbon nanotube side walls. Single molecule fluorescence revealed that on
attachment to SWCNTs GFP’s fluorescence changed in terms of intensity and
improved resistance to photobleaching; essentially GFP is fluorescent for much
longer on attachment. The site of attachment proved important in terms of
electronic impact on GFP function, with the attachment site furthest from the
functional center having the larger effect on fluorescence. Our approach
provides a versatile and general method for generating intimate protein-CNT
hybrid bioconjugates. It can be potentially applied easily to any protein of
choice; attachment position and thus interface characteristics with the CNT can
easily be changed by simply placing the phenyl azide chemistry at different
residues by gene mutagenesis. Thus, our approach will allow consistent
construction and modulate functional coupling through changing the protein attachment
position.</p>
