Controlling the non-linear emission of upconversion nanoparticles to enhance super-resolution imaging performance

TL;DR

This paper explores how controlling the non-linear emission of Yb-based upconversion nanoparticles can improve super-resolution imaging techniques like STED and uSEE microscopy, enabling lower power requirements and multiplexed imaging.

Contribution

It demonstrates that tuning the power-dependent emission of UCNPs relaxes doping constraints and reduces excitation power for super-resolution imaging, advancing nanoparticle application methods.

Findings

Controlled emission curves enable lower excitation power.

Relaxed doping constraints improve nanoparticle design.

Achieved multiplexed super-resolution imaging.

Abstract

Upconversion nanoparticles (UCNPs) exhibit unique optical properties such as photo-emission stability, large anti-Stokes shift, and long excited-state lifetimes, allowing significant advances in a broad range of applications from biomedical sensing to super-resolution microscopy. In recent years, progress on nanoparticle synthesis led to the development of many strategies for enhancing their upconversion luminescence, focused in particular on heavy doping of lanthanide ions and core-shell structures. In this article, we investigate the non-linear emission properties of fully Yb-based core-shell UCNPs and their impact on the super-resolution performance of stimulated excitation-depletion (STED) microscopy and super-linear excitation-emission (uSEE) microscopy. Controlling the power-dependent emission curve enables us to relax constraints on the doping concentrations and to reduce the excitation power required for accessing sub-diffraction regimes. We take advantage of this feature to implement multiplexed super-resolution imaging of a two-sample mixture.