Owing to their small size (normally in the range of 1 – 100 nm), nanoparticles exhibit unique physico-chemical properties, which are different from those of bulk materials, and that can be used to construct novel and improved sensing devices; in particular, optical sensors and biosensors. Only recently, nanoparticle based optical sensors have been developed that are now capable of detecting even single small molecules and their reactions (1). The application of nanoparticle-based sensors in single-molecule biosensing opens up a range of interesting fundamental studies and applications. For example, the next generation of bioanalytical devices will be based on ‘smart’ nanoparticles to analyse biological and environmental samples at the single molecule level.
We are interested in developing nanoparticle-based single molecule sensors by controlling synthesis of the nanoparticles. Our goal is to synthesize nanoparticles with specific chemical and optical properties. Examples for this are nanoparticles that respond to light at a certain wavelength and that catalyse chemical reactions. The nanoparticle chemistry combined with single-molecule sensitivity of the nanoparticle sensors gives us an eye into the nanoworld. Our laboratory uses this ‘eye’ to observe chemistry and chemical reactions not accessible with traditional analytical chemistry tools. With our single-molecule nanoparticle sensors we are able to understand mechanisms of catalysis. We can control chemical reactions with light. We explore surface-based reactions and their mechanisms, especially those that have been obfuscated by the use of traditional analysis techniques.