pHe-induced charge-reversible NIR fluorescence nanoprobe for tumor-specific imaging

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Oncology

Background:

• Tumor microenvironments often exhibit acidic extracellular pH (pHe).
• Targeted cancer imaging requires specific probes that can navigate and accumulate within tumors.
• Existing imaging probes may lack specificity or efficient tumor cell uptake mechanisms.

Purpose of the Study:

• To construct a flexible, charge-reversible near-infrared (NIR) fluorescence nanoprobe.
• To enable effective tumor-specific imaging by responding to the acidic tumor extracellular pH (pHe).
• To investigate the nanoprobe's potential for enhanced tumor cell uptake and broader theranostics applications.

Main Methods:

• Synthesized a nanoprobe using CuInS2/ZnS quantum dot (CIS/ZS QDs) core and a modified ε-polylysine (ε-PL-g-LA/DMA) shell.
• Evaluated the nanoprobe's stability, optical properties, and charge-reversal behavior in response to pH changes.
• Assessed cell uptake efficiency in HeLa cells at different pH levels (6.8 vs. 7.4) to confirm pHe-induced targeting.

Main Results:

• The QDs@ε-PL-g-LA/DMA nanoprobe exhibited high chemical stability and excellent optical properties.
• The nanoprobe demonstrated swift surface charge reversal from negative to positive within 20 minutes at acidic pHe (pH 6.8).
• Significantly enhanced cellular uptake was observed in HeLa cells at pH 6.8 compared to pH 7.4, validating pHe-triggered endocytosis.

Conclusions:

• The developed nanoprobe effectively targets tumors via pHe-induced charge reversal and enhanced endocytosis.
• This charge-reversion strategy offers broad applicability for targeting various solid tumors.
• The responsive charge reversion mechanism is a promising alternative for cancer theranostics agents.