Noninvasive Imaging of Quantum Dots in Mice

TLDR

Four surface‑coated quantum dots were evaluated for in vivo imaging. Quantum dots were successfully tracked from centimeters to nanometers using fluorescence imaging, necropsy, optical microscopy, and electron microscopy; short‑chain and amphiphilic coatings had half‑lives <12 min, long‑chain methoxy‑PEG ~70 min, long‑chain carboxy‑PEG similar, and long‑chain methoxy‑PEG remained fluorescent for at least four months.

Abstract

Quantum dots having four different surface coatings were tested for use in in vivo imaging. Localization was successfully monitored by fluorescence imaging of living animals, by necropsy, by frozen tissue sections for optical microscopy, and by electron microscopy, on scales ranging from centimeters to nanometers, using only quantum dots for detection. Circulating half-lives were found to be less than 12 min for amphiphilic poly(acrylic acid), short-chain (750 Da) methoxy-PEG or long-chain (3400 Da) carboxy-PEG quantum dots, but approximately 70 min for long-chain (5000 Da) methoxy-PEG quantum dots. Surface coatings also determined the in vivo localization of the quantum dots. Long-term experiments demonstrated that these quantum dots remain fluorescent after at least four months in vivo.