Layer-by-layer functionalization of carbon nanotubes with synthetic and natural polyelectrolytes

The surface of carbon nanotubes was noncovalently modified by layer-by-layer deposition of synthetic polyelectrolytes. The efficiency of an easy functionalization process based on alternatively dipping of carbon nanotubes into solutions containing oppositely charged polyelectrolytes was demonstrated. From transmission electron microscopy (TEM) analysis, it was shown that the thickness of the adsorbed polyelectrolyte layers increases linearly with the bilayers number up to reach 6 nm. This easy functionalization covered homogeneously the whole surface of nanotubes as revealed by atomic force microscopy (AFM) images. Then, the adsorbed polyelectrolyte layers were used as anchoring ones to subsequently graft a natural biopolymer. Such postfunctionalization opens the way to design new (nano)biodevices based on carbon nanotubes.