The conversion of azo-quenchers to fluorophores

GLUT1 targeting and hypoxia-activating polymer-drug conjugate-based micelle for tumor chemo-thermal therapy

Purpose

Mitochondria are closely correlated with the proliferation and metastasis of tumor for providing suitable micro-environment and energy supply. Herein, we construct a glucose transporter 1 (GLUT1) targeting and hypoxia activating polyprodrug-based micelle (Glu-PEG-Azo-IR808-S-S-PTX) for mitochondria-specific drug delivery and tumor chemo-thermal therapy.

Results

The micelle was characterized by hypoxia-sensitive PEG outer layer detachment, high photo-thermal conversion efficiency, and glutathione (GSH)-sensitive paclitaxel （PTX） release. It showed GLUT1 specifically cellular uptake and hypoxia-sensitive mitochondria targeting on A549 cell. In vivo fluorescence imaging confirmed the micelle also could selectively accumulate in tumor and its mitochondria on A549 tumor-bearing nude mice. Consequently, it not only exhibited higher cytotoxicity, apoptosis rate, and metastasis inhibition rate on A549 cells, but also better tumor growth and metastasis inhibition rate on tumor-bearing nude mice and lower whole-body toxicity. The mechanism might be caused by destroying mitochondria and down-regulating ATP production.

Conclusion

This study provided a GLUT1 targeting, hypoxia, and reductive responsive nanomedicine that hold the potential to be exploited for tumor therapy.

Precisely Traceable Drug Delivery of Azoreductase-Responsive Prodrug for Colon Targeting via Multimodal Imaging

We report the development of an azoreductase-responsive prodrug AP-N═N-Cy in which the precursor compound AP, a readily available podophyllotoxin derivative, is linked with a NIR fluorophore (Cy) via a multifunctional azobenzene group. This type of azo-based prodrug can serve as not only an azoreductase-responsive NIR probe to real-time tracking of the drug delivery process but also a delivery platform for an anticancer compound (AdP). We have shown that cleavage of the multifunctional azobenzene group in AP-N═N-Cy only occurred in the presence of azoreductase, which specifically secretes in the colon, resulting in direct release of AdP through an in situ modification of a phenylamino group on the precursor AP. Moreover, introduction of the azobenzene group endows the prodrug with an unique fluorescence "off-on" property and served as a switch to "turn on" the fluorescence of Cy as consequence of a self-elimination reaction with breakage of an azo bond. Such a prodrug can be administered orally and exhibit high stability and low toxicity before arriving at the colon. In view of the synchronism of drug release and the fluorescence turn-on process, the fluorescence imaging method was utilized to precisely trace drug delivery in vitro, ex vivo, and in vivo. Distinguishingly, the biodistribution of AdP and Cy in various tissues was further precisely mapped at the molecular level using imaging mass spectrometry. To the best of our knowledge, this is the first time that the in vivo real-time precise tracking of the colon-specific drug release and biodistribution was reported via a multimodal imaging method.

Azo-based near-infrared fluorescent theranostic probe for tracking hypoxia-activated cancer chemotherapy in vivo

A novel azo-based near-infrared fluorescent therabostic probe activated by hypoxia is applied to real-time visualization of drug delivery in vivo.