Water-Soluble Quantum Dots for Multiphoton Fluorescence Imaging in Vivo

TLDR

Semiconductor quantum dots enable multicolor multiphoton microscopy in challenging biological settings such as living tissue. The authors characterized water‑soluble cadmium selenide‑zinc sulfide quantum dots for multiphoton imaging in live animals. These probes exhibit two‑photon action cross sections up to 47,000 GM—the highest reported—allowing visualization through mouse skin to capillaries hundreds of micrometers deep while showing no blinking on nanosecond‑to‑millisecond timescales.

Abstract

The use of semiconductor nanocrystals (quantum dots) as fluorescent labels for multiphoton microscopy enables multicolor imaging in demanding biological environments such as living tissue. We characterized water-soluble cadmium selenide-zinc sulfide quantum dots for multiphoton imaging in live animals. These fluorescent probes have two-photon action cross sections as high as 47,000 Goeppert-Mayer units, by far the largest of any label used in multiphoton microscopy. We visualized quantum dots dynamically through the skin of living mice, in capillaries hundreds of micrometers deep. We found no evidence of blinking (fluorescence intermittency) in solution on nanosecond to millisecond time scales.