The screening for specific biomolecular binding utilizing biochips bases usually on a flurescence signal. Flurescence labeling is limited regarding the sensitivity and the spatial resolution, and there is a need for a sophisticated detection equipment for sensing and processing the signals. We describe here the application of metal nanoparticles as labels. Such labels were used for an optical detection of DNA-DNA-interaction on glass substrates without the need for a fluorescence set-up. Exposure times down to the ms-range are sufficient to yield an high-contrast image. Another novel method for read-out of DNA-chips is based on an electrical detection of the nanoparticles by using electrode gaps. The specific binding of particles in the gap and an enhancement-scheme based on electroless metal deposition will be demonstrated.