Because of their extraordinary electronic and mechanical properties, carbon nanotubes have great potential as materials for applications ranging from molecular electronics to ultrasensitive biosensors. Biological molecules interacting with carbon nanotubes provide them with specific chemical handles that would make several of these applications possible. Here we use phage display to identify peptides with selective affinity for carbon nanotubes. Binding specificity has been confirmed by demonstrating direct attachment of nanotubes to phage and free peptides immobilized on microspheres. Consensus binding sequences show a motif rich in histidine and tryptophan, at specific locations. Our analysis of peptide conformations shows that the binding sequence is flexible and folds into a structure matching the geometry of carbon nanotubes. The hydrophobic structure of the peptide chains suggests that they act as symmetric detergents.

A scanning transmission electron microscope (STEM) technique was used to measure Mo concentrations at ferrite:austenite (␣:␥) interfaces in an Fe-0.24 pct C-0.93 pct Mo alloy partially transformed at 650°C, 630°C, and 610°C. These concentrations were quite small at 650°C, which is just below the bay temperature of the time-temperature-transformation (TTT) curve for the initiation of ferrite formation. There were larger concentrations at 630°C, a temperature at which transformation stasis (incomplete transformation) occurred. Concentrations at 610°C were intermediate between the values observed at 650°C and 630°C. The average accumulation at the latter temperatures increased appreciably as a function of transformation time. After each heat treatment, there was considerable variation in Mo accumulation from one ␣:␥ interface to another and, to a lesser extent, from one region to another along the same interface. These higher Mo concentrations were deduced to have developed largely through volume diffusion of Mo, mainly through ferrite, to interfaces whose ledgewise growth had been interrupted by growth stasis. (Mo 2 C precipitation at ␣:␥ boundaries occurred only at the end of growth stasis.) It appears that only a very small amount of Mo segregation is needed, probably at specific interfacial sites, in order to produce growth cessation. Growth kinetics anomalies of this kind continue to provide the best evidence available for the operation of a coupled-solute drag effect.

Three different types of carbon nanotubes being considered for bio-recognition experiments were studied using resonance Raman spectroscopy. Raman spectroscopy, taken using several laser excitation energies, has been shown to provide an effective characterization tool for these carbon nanotubes. The technique yields structural information that both complements and corroborates structural information obtained using electron microscopy techniques, such as TEM, SEM, and AFM.