Detection and quantification of DNA adsorbed on solid surfaces by using liquid crystals.

Conventional DNA detection is often accomplished by using UV-vis or fluorescence spectrometry, which requires at least 1 microL of DNA solution. Herein, we report a label-free, liquid-crystal (LC)-based DNA quantification method that is suitable for characterizing DNA solution volumes of <1 microL. The detection principle of this method is based on the disruption of the orientations of LCs by surface-immobilized DNA, which leads to distinct optical textures of LCs visible to the naked eye. However, this method is successful only when the buffer contains divalent cations such as calcium or magnesium. The limit of detection of this method is approximately 4 microg/mL DNA, and only 10 nL of DNA solution is required, which means that as little as 40 pg of DNA can be detected by using this method. This LC-based detection method is also simple to apply and has the potential to be integrated with lab-on-a-chip devices for DNA analysis.