Novel DNA sensor
doi:10.1038/nindia.2011.14 Published online 31 January 2011
Researchers have designed a new biosensor that can detect important biological structures such as DNA. They made the sensor by modifying and linking zinc sulphide (ZnS) nanocrystals to single-walled carbon nanotubes (SWNTs).
To design an efficient DNA sensor, the researchers decorated SWNT with ZnS nanocrystals. Then they loaded a single-strand DNA (ssDNA) probe that acts as a field-effect transistor onto the ZnS nanocrystals. For comparative study, the researchers also produced a bare SWNT without any attached nanocrystals. The ssDNA probe used to sense target DNA is known as complimentary ssDNA (c-ssDNA).
The fabrication and sensing processes were monitored by recording the current–voltage characteristics of the device, which responded explicitly to different concentrations of c ssDNA due to hybridization with ssDNA. However, the device did not respond to non-complimentary-ssDNA due to mismatch.
The ZnS/SWNT-ssDNA device exhibited a 2.5-fold increase in sensitivity over the bare SWNT. This significant increase in sensitivity towards c ssDNA may be attributed to an increased loading of the ssDNA probe over ZnS nanocrystals due to their large surface-to-volume ratio and a subsequent transfer of electrons to the SWNT upon hybridization with c ssDNA.
The device looks promising for nanobiosensors that demand high performance, the researchers say.
The authors of this work are from: Department of Chemical and Environmental Engineering, University of California, Riverside, California, USA and Polymer and Soft Material Section, National Physical Laboratory (Council of Scientific and Industrial Research), New Delhi, India.
- [author]Rajesh.[/author] et al. ZnS nanocrystals decorated single-walled carbon nanotube based chemiresistive label-free DNA sensor. Appl. Phys. Lett. 98, 013701(2011)