A Nano-Biosensor for DNA Sequence Detection Using Absorption Spectra of SWNT-DNA Composite

Author(s) J. Bansal, I. Singh, N. Mathur, A. Aneja, P.K. Bhatnagar, P.C. Mathur
Affiliations University of Delhi South Campus, Benito Juarez Road, New Delhi-21, India
Е-mail jyoti_2681986@yahoo.com
Issue Volume 3, Year 2011, Number 1, Part 4
Dates Received 04 February 2011, in final form 14 October 2011, published online 17 October 2011
Citation J. Bansal, I. Singh, N. Mathur, A. Aneja, P.K. Bhatnagar, P.C. Mathur, J. Nano- Electron. Phys. 3 No1, 776 (2011)
PACS Number(s) 87.14.gk, 61.48.De
Key words Biosensor (4) , DNA, SWNT (2) , Absorption (14) , Exciton binding energy (2) , Chirality.
A biosensor based on Single Walled Carbon Nanotube (SWNT)-Poly (GT)n ssDNA hybrid has been developed for medical diagnostics. The absorption spectrum of this assay is determined with the help of a Shimadzu UV-VIS-NIR spectrophotometer. Two distinct bands each containing three peaks corresponding to first and second van Hove singularities in the density of states of the nanotubes were observed in the absorption spectrum. When a single-stranded DNA (ssDNA) having a sequence complementary to probic DNA is added to the ssDNA-SWNT conjugates, hybridization takes place, which causes the red shift of absorption spectrum of nanotubes. On the other hand, when the DNA is noncomplementary, no shift in the absorption spectrum occurs since hybridization between the DNA and probe does not take place. The red shifting of the spectrum is considered to be due to change in the dielectric environment around nanotubes.