Azoreductase-Responsive Nanoprobe for Hypoxia-Induced Mitophagy Imaging

Area of Science:

• Biochemistry
• Cell Biology
• Nanotechnology

Background:

• Mitophagy is vital for cellular homeostasis and is induced by stresses like hypoxia, which increases reactive oxygen species (ROS).
• Accurate, high-specificity fluorescence imaging of mitophagy in living cells under hypoxic conditions remains a significant challenge.
• Understanding mitophagy is crucial for research into hypoxia-related diseases and cancer therapies.

Purpose of the Study:

• To develop a novel nanoprobe for specific and sensitive fluorescence imaging of mitophagy in living cells under hypoxia.
• To create a tool that can overcome limitations of current imaging techniques for mitophagy.
• To explore the potential application of this nanoprobe in hypoxia-induced conditions, such as cancer treated with photodynamic therapy (PDT).

Main Methods:

• A responsive nanoprobe, Micelle@Mito-rHP@TATp (MCM@TATp), was synthesized by encapsulating a cationic spiropyrane derivative (Mito-rHP) within an azoreductase-responsive micelle.
• The micelle was formed from an azoreductase-responsive amphiphilic polymer (Mal-PEG2000-Azo-DSPE).
• The nanoprobe surface was modified with a cell-penetrating peptide (TATp) to prevent endolysosomal trapping and enhance mitochondrial targeting.

Main Results:

• The MCM@TATp nanoprobe demonstrated high specificity for imaging mitophagy in living cells under hypoxia.
• Under hypoxic conditions, the probe exhibited an 'off-on' fluorescence response upon release of Mito-rHP into mitochondria, correlating with mitophagy-induced acidification.
• The nanoprobe successfully imaged mitophagy in a cancer model undergoing photodynamic therapy (PDT), which induces hypoxia.

Conclusions:

• The developed MCM@TATp nanoprobe offers a powerful new strategy for specific mitophagy imaging in hypoxic environments.
• This tool is valuable for fundamental research into hypoxia-related cellular processes and clinical applications.
• The findings suggest potential for MCM@TATp in advancing research for hypoxia-related diseases and cancer therapy monitoring.