Efficient bioimaging using rare-earth-doped carbon quantum dots: A doping strategy

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Carbon quantum dots (CQDs) face challenges in bioimaging, including low photoluminescence quantum yield (PLQY) and complex purification.
• Developing novel nanomaterials with enhanced optical properties and biocompatibility is crucial for advanced bioimaging.

Purpose of the Study:

• To synthesize lanthanide-doped carbon quantum dots (L-CQDs) to address the limitations of traditional CQDs.
• To enhance the PLQY and simplify the purification process for CQDs.
• To evaluate the potential of L-CQDs for cellular labeling and in vivo fluorescence imaging.

Main Methods:

• One-pot microwave-assisted solvothermal synthesis of L-CQDs using citric acid, urea, neodymium chloride, and cerium chloride in a glycerol-water system.
• Characterization of L-CQDs for structure, size, and optical properties, including PLQY measurement.
• Assessment of L-CQD biosafety in various cell lines (HUVEC, RAW264.7) and in vivo (C57 mice), and evaluation of their bioimaging performance.

Main Results:

• Achieved a significant enhancement in PLQY from 0.43% to 69% through lanthanide doping (cerium and neodymium).
• Synthesized graphene-like L-CQDs (≈8 nm) with anti-Stokes blue emission and demonstrated efficient purification via ethanol precipitation.
• Confirmed excellent biosafety and observed enhanced fluorescence intensity with specific accumulation in highly perfused organs, including the brain, indicating blood-brain barrier penetration.

Conclusions:

• Lanthanide-doped carbon quantum dots (L-CQDs) offer a promising solution for overcoming the limitations of traditional CQDs in bioimaging.
• The developed L-CQDs exhibit superior optical properties, efficient purification, and excellent biocompatibility.
• L-CQDs demonstrate significant potential for advanced cellular labeling and in vivo fluorescence imaging applications, including crossing the blood-brain barrier.