In Vivo Imaging of Quantum Dots Encapsulated in Phospholipid Micelles

TLDR

Fluorescent semiconductor nanocrystals (quantum dots) promise transformative biological imaging but are limited by challenges in achieving biocompatibility. The study seeks to overcome these limitations by encapsulating individual quantum dots in phospholipid block–copolymer micelles. The authors encapsulated the nanocrystals in micelles and demonstrated both in vitro and in vivo imaging capabilities. The micelle‑encapsulated quantum dots, when conjugated to DNA, served as fluorescent probes for specific hybridization, remained stable, non‑toxic (<5 × 10⁹ nanocrystals per cell), cell‑autonomous, and photostable in Xenopus embryos, allowing fluorescence tracking through tadpole development for lineage‑tracing experiments.

Abstract

Fluorescent semiconductor nanocrystals (quantum dots) have the potential to revolutionize biological imaging, but their use has been limited by difficulties in obtaining nanocrystals that are biocompatible. To address this problem, we encapsulated individual nanocrystals in phospholipid block–copolymer micelles and demonstrated both in vitro and in vivo imaging. When conjugated to DNA, the nanocrystal-micelles acted as in vitro fluorescent probes to hybridize to specific complementary sequences. Moreover, when injected into Xenopus embryos, the nanocrystal-micelles were stable, nontoxic (&lt;5 × 10 9 nanocrystals per cell), cell autonomous, and slow to photobleach. Nanocrystal fluorescence could be followed to the tadpole stage, allowing lineage-tracing experiments in embryogenesis.