U.S. flag

An official website of the United States government, Department of Justice.

Charge Tags as Electronic Labels for DNA Microchip Testing

NCJ Number
Date Published
June 2004
29 pages
This study tested whether electronic labels called “charge tags” could be used for the detection of DNA Short Tandem Repeat (STR) fragments for use on microchips.
The purpose of the study was to create a revolutionary new technique that would improve over the use of Dielectric Relaxation Spectroscopy (DRS), typically used for the detection of DNA STR fragments. DRS analyzes polarizes molecules through AC impedance changes during high frequency sweeps. This process is limited by such issues as high conductivity of physiologic solutions and spectral blurring as a result of complex charge geometry. The current method proposed to engineer dipoles and create sudden and large dipole shifts that could be used to generate a specific signal. It was proposed that this signal would relate to the dipole length, which would thus differentiate STR fragment length sizes. The researchers were able to generate DRS signals from certain small molecules but were unable to obtain a signal using DNA fragments. High salt concentrations were necessary to keep the high concentrations of DNA in solution; the salt created a significantly large dipole signal that masked the signal the researchers were attempting to detect. Future attempts to obtain a DAN signal should focus on electrode charge bias or surface binding experiments. Figure, references

Date Published: June 1, 2004