Our group is focused on defining the cutting-edge development of lanthanide-doped upconverting nanoparticles (UCNPs) as next-generation imaging probes, sensors, and sources of local light.
Photon upconversion, the process of combining multiple low-energy photons into a single higher-energy photon, underlies advanced optical technologies in solar light harvesting, deep-tissue bioimaging, sensing, and optogenetics. Lanthanide-doped upconverting nanoparticles (UCNPs) lay at the forefront of these research efforts, as they are capable of upconverting light 5-6 orders of magnitude more efficiently than other nonlinear materials, including the best 2-photon dyes.
Our team was the first to image and characterize UCNPs at the single-molecule level, demonstrating the non-blinking, non-bleaching, background-free imaging properties of UCNPs, and thereby establishing their potential as near-ideal single-particle luminescent reporters and nanoscale “lightbulbs”. We perform detailed investigations of UCNP photophysics including the energy transfer kinetics between lanthanide ions within UCNPs and between UCNPs and other materials. This enables the ability to model, design and demonstrate many classes of UCNPs, with each optimized for a specific application.
A current direction includes coupling UCNPs with molecular reporters and tunable plasmon resonances in doped semiconductors to make these UCNPs sensitive to changes in local environments and local chemistry, including the sensing of temperature, pressure, ion concentrations (e.g. Na, K, Ca), neurotransmitters. Another effort focuses on using specifically-engineered UCNPs as gain media for the smallest-ever – and lowest threshold – upconverting micro- and nano-lasers.