Optimal design of structured nanospheres for ultrasharp light-scattering resonances as molecular imaging multilabels

Optical molecular imaging could potentially enable noninvasive high-resolution characterization and diagnosis of living tissue. The capability to image multiple molecular targets simultaneously is particularly important. Currently this task cannot be achieved using conventional optical contrast agents, due to their broad spectral responses (approximately 80 to 200 nm). Developments in research on semiconductor nanocrystals (quantum dots) provide one possible solution. We describe a different concept of multilabel molecular imaging that utilizes resonant light-scattering spectroscopy of multilayered nanospheres to achieve tunable ultrasharp resonance peaks with widths as narrow as 10 nm. Our theoretical study demonstrates that dozens of molecular targets can potentially be imaged simultaneously using this approach.