Abstract

Upconverting nanoparticles providing means for deep tissue optical imaging and photoactivation

Stefan Andersson-Engels, Director, Lund University Medical Laser Centre

Upconverting nanoparticles have recently drawn increasingly attention as contrast agents for optical bioimaging. They enable autofluorescence-free imaging within the tissue optical window, and improved spatial resolution as compared to conventional fluorescence-based contrast agents. We illustrate first a significant improvement in spatial resolution for UCNPs as compared to conventional dye fluorophores, due to the non-linear dependence on the excitation light fluence distribution within a tissue phantom for the UCNPs. By shifting the wavelengths of conventional NaYF4-based nanoparticles, we illustrate improved depth sensitivity. This can be utilized for both imaging and photoactivation applications. The results suggest that UCNPs can be very powerful as contrast agents for small animal optical imaging.