Bionanotechnology provides an attractive and a unique arena for biochemists, biologists and physicists due to its interdisciplinary nature. The nanoscopic size of metallic nanoparticles provides a large surface-area to volume ratio, as the percentage of surface atoms increases rapidly with decreasing particle size. Surface modification chemistry is therefore needed to compatibilize nanoparticles and biological systems. The capability to integrate the functional properties of the core and the surface monolayer is the key to fulfill the potentials of these nanoscopic materials in the biotechnology.