Electronic, chemical sensing, and structural properties of single stranded DNA functionalized, single walled carbon nanotube devices

The integration of SWNT\u27s with biomolecules is allows for taking advantage of the strengths of both, the electronic properties and structure of the SWNT combined with the diversity of biomolecules provides a platform to investigate a multitude of interesting phenomena. We have conducted experiments to probe the electronic, chemical sensing and structural properties of single walled carbon nanotubes (SWNT\u27s) functionalized with single stranded DNA (ssDNA). We have developed a method for producing high quality contacts to SWNT\u27s, allowing for devices with pristine surface chemistries, so that we can study the interactions of the ssDNA with the SWNT in the absence of other chemical contaminants. We have studied the chemical sensing properties of SWNT FET\u27s functionalized with various sequences of ssDNA, in order to test that the sequence of the adsorbed DNA modulates the sensing response. We find that the order of bases in a sequence is the driving force which modulates the sensing response, not the base content, we also find that a linear combination of responses obtained by devices functionalized with single nucleotide strands cannot recreate the response of a random sequence. Building on that result, we have shown the first instance of chiral molecule discrimination by an artificial electronic chemical sensing platform. We present data from a library representing thousands of devices measured with a variety of ssDNA sequences, screened against a variety of analytes to support this result. Finally, we have conducted experiments to probe the structure of the adsorbed ssDNA on SWNT\u27s by Fourier Transform Infrared Spectroscopy (FTIR), and have discovered that Watson-Crick base-pairing within sequences adsorbed to SWNT\u27s can modulate the sensing response of that device to given analytes. We present structural probes of the ssDNA strands representative of our library, and test our model on an idealized ssDNA configuration to confirm our result that base-pairing indeed modulates the gas sensing properties of SWNT/ssDNA hybrid devices. This insight paves the way for the use of SWNT\u27s functionalized with ssDNA as a generic chemical binding site which can be interfaced with electronic, gravimetric or any number of other platforms requiring a diverse chemical recognitions site