Micelle-based activatable probe for in vivo near-infrared optical imaging of cancer biomolecules.

Abstract

Near-infrared (NIR: 800-1000nm) fluorescent probes, which activate their fluorescence following interaction with functional biomolecules, are desirable for noninvasive and sensitive tumor diagnosis due to minimal tissue interference. Focusing on bioavailability and applicability, we developed a probe with a self-assembling polymer micelle, a lactosome, encapsulating various quantities of NIR dye (IC7-1). We also conjugated anti-HER2 single chain antibodies to the lactosome surface and examined the probe's capacity to detect HER2 in cells and in vivo. Micelles encapsulating 20mol% IC7-1 (hIC7L) showed 30-fold higher fluorescence (λem: 858nm) after micelle denaturation compared to aqueous buffer. Furthermore, antibody modification allowed specific activation of the probe (HER2-hIC7L) following internalization by HER2-positive cells, with the probe concentrating in lysosomes. HER2-hIC7L intravenously administered to mice clearly and specifically visualized HER2-positive tumors by in vivo optical imaging. These results indicate that HER2-hIC7L is a potential activatable NIR probe for sensitive tumor diagnosis.