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Far red‐shifted CdTe quantum dots for multicolour STED nanoscopy
Jonatan Alvelid, Andrea Bucci, Ilaria Testa
Multicolor STED, Quantum Dots, Nanoscopy
Stimulated emission depletion (STED) nanoscopy is a widely used nanoscopy technique. Two-colour STED imaging in fixed and living cells is today standardised utilising both fluorescent dyes and fluorescent proteins. Solutions to image additional colours have been demonstrated using spectral unmixing, photobleaching steps, or long-Stokes-shift dyes. However, these approaches often compromise speed, spatial resolution, image quality, and increase complexity. Here, we present multicolour STED nanoscopy with far red-shifted semiconductor CdTe quantum dots (QDs). STED imaging of the QDs is optimized in order to minimize blinking effects and maximize detected photons. The far-red and compact emission spectra of the investigated QDs free spectral space for the simultaneous use of fluorescent dyes, enabling straightforward three-colour STED imaging with a single depletion beam. We used our methods to study the internalization of QDs in cells, opening the way for future super-resolution studies of particle uptake and internalization.