Research Highlight

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.


  1. [author]Rajesh.[/author] et al. ZnS nanocrystals decorated single-walled carbon nanotube based chemiresistive label-free DNA sensor. Appl. Phys. Lett. 98, 013701(2011)