Molecular imaging and darkfield microspectroscopy of live cells using gold plasmonic nanoparticles

Noble metal nanoparticles exhibit a plasmonic resonance that provides them with unique optical properties. The sensitivity of the plasmonic resonance to the surrounding dielectric environment has lead to the development of metal nanoparticles as the basis of biosensing schemes. The sharp enhancement in scattering and absorption at the plasmonic resonance frequency has been exploited to develop metal nanoparticles as imaging contrast agents. In this review article, we recap recent efforts that combine both of these features of metal nanoparticles to enable simultaneous molecular imaging and environmental sensing through the use of darkfield microspectroscopy schemes. Recent experimental results demonstrate molecular imaging of epidermal growth factor receptor in live cancer cells and show that additional information can be obtained by monitoring changes in the plasmonic resonance through darkfield microspectroscopy