The effect of sequence length on DNA decorated CNT gas sensors

This article reports the effect of deoxyribonucleic acid (DNA) sequence length on the sensing characteristics of DNA decorated single-walled carbon nanotube (SWNT) devices. First, SWNTs were assembled on micro electrodes via a versatile, solution based Dielectrophoresis process. Then four single-stranded poly-G oligomers with lengths of 8, 16, 24 and 32 were decorated on SWNTs and the response of SWNT sensors to methanol and IPA vapors were measured. We found that the optimum DNA sequence length for sensing applications was 24. Sequence length of DNA had a dramatic impact on the response of DNA-SWNT sensors. This phenomenon can be explained by the difference in binding affinities of nucleotides on SWNTs and the conformations that DNA forms on SWNTs. These experimental results have significant implications for the interactions between DNA and SWNTs. They can facilitate the development of DNA functionalized SWNT sensors in analytical chemistry, biochemistry and environmental monitoring applications.