At BSE lab, we develop biofunctionalized nanomaterials capable of detecting, from complex biological fluids, chemicals and biological molecules of interest with high levels of sensitivity and selectivity. We rely on localized surface plasmon resonance (LSPR) and surface-enhanced Raman spectroscopy (SERS) for detection conducted both in solution as well as on solid substrates. Our plasmon-active materials range from single nanoparticles and nanoparticle dimers to long-range nanoparticle assemblies and hierarchical organic-inorganic nanocomposites. They can translate molecular binding events to an optical signal that can even be visible via naked eye. Most notably, we have shown that the controlled formation of nanoparticle dimers in solution for DNA sensing via LSPR-based colorimetry can tremendously improve the detection sensitivity by four orders of magnitude.