Detection and identification of individual biomolecules translocating through a carbon nanotube – Nanophoresis

Novel analysis techniques are actively sought to hold the promise of personalized DNA sequencing and high-throughput screening of proteins at affordable cost and viable time. Among those, nanopore sensing of single biomolecules represents a path-breaking technology because it represents a label-free and amplification-free approach that is scalable for high-throughput analysis. Most research to date has focused on biological nanopores and on nanoperforations drilled in thin solid-state membranes. These nanopores yielded many remarkable results but also have important limitations such as the difficulty to engineer them with atomic scale precision. Sequencing systems based on such nanopores are announced for commercialization in 2013 once their error rate has been lowered to acceptable values. However, it is unlikely that a single type of nanopore will fulfil the requirements for all the applications envisioned for nanopore sensing; different types of nanopores will be required for different types of applications. Actually, synthetic nanochannels having a versatile and perfectly-defined atomic structure do exist in the form of single-walled carbon nanotubes (SWNTs). Our previous works notably established methods to prepare long and individual SWNTs, characterize their atomic structures by optical spectroscopy and integrate them in functional devices.
This project aims at exploring the potential of SWNTs for nanopore sensing, as an alternative to the short biochannels and nano-perforations essentially used so far. Specifically, we will investigate the aptitude of SWNT devices for discriminating single small biomolecules, using nucleotides and amino acids as model compounds. To do so, we will fabricate microfluidic devices integrating individual SWNTs previously identified by Raman spectroscopy. We will perform patch-clamp-type experiments to investigate and rationalize the parameter dependence of the ionic conductance in SWNT channels. We will investigate the electrophoretic translocation of nucleotides and amino acids in individual SWNTs and evaluate the identification accuracy relying on both the conductance drop and dwell time of the current blocking events. This research is expected to result in an improved understanding of molecular transport in nanochannels and in the development of an accurate identification method of single small biomolecules. Such a method is expected to be extremely valuable for both basic biological research and bioanalytical applications.