A high precision length-based carbon nanotube ladder

Today, carbon nanotubes manufacturers as well as users such as molecular electronics, nanomedicine, nano-biotechnology and similar industries are facing a major challenge: lack of length uniformity of carbon nanotubes in mass production. An effective solution to this major issue is the use of a length-based ladder. We are, for the first time, presenting such a valuable tool to determine the length purity. Our length-based carbon nanotubes ladder, containing a series of carbon nanotubes markers with different lengths, is made based on three combined techniques - bio-conjugation, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and silver staining. Creating an indicator using conjugation of a biomolecule with carbon nanotubes to make a carbon nanotubes ladder is a novel idea and a significant step forward for length-based carbon nanotubes separation. The very sensitive silver staining technique allows a precise visualization and quantification of the gel. This ladder with a pending patent by Northeastern University is an effective quality control tool when bulk quantities of nanotubes with a desirable length are manufactured.