Near-infrared fluorescent type II quantum dots for sentinel lymph node mapping

Area of Science:

• Biomedical imaging
• Nanotechnology
• Optical engineering

Background:

• Near-infrared (NIR) and infrared photons are crucial for deep-tissue biomedical imaging.
• Conventional organic fluorophores often lack the required properties (size, absorption, quantum yield, stability) for effective contrast agents.
• Development of novel contrast agents is essential for advancing in vivo imaging techniques.

Purpose of the Study:

• To develop novel near-infrared emitting quantum dots (QDs) for enhanced biomedical imaging.
• To functionalize QDs with a polydentate phosphine coating for improved solubility, dispersion, and stability in biological environments.
• To demonstrate the efficacy of these NIR QDs in real-time sentinel lymph node mapping in large animal models.

Main Methods:

• Type II quantum dots were synthesized and their fluorescence emission tuned to the near-infrared spectrum.
• A polydentate phosphine coating was applied to enhance QD solubility and stability in serum.
• In vivo studies were conducted using large animals for sentinel lymph node mapping under image guidance.

Main Results:

• Near-infrared emission was achieved while preserving the absorption cross-section of the QDs.
• The phosphine coating ensured QD solubility, dispersion, and stability in serum.
• Sentinel lymph nodes up to 1 cm deep were successfully imaged in real-time in large animals using low excitation fluence rates (5 mW/cm(2)) with only 400 pmol of NIR QDs.

Conclusions:

• The developed near-infrared quantum dots possess optimal chemical, optical, and in vivo properties for biomedical imaging.
• These NIR QDs represent a significant advancement for surgical guidance, particularly in cancer detection and mapping.
• The study highlights the broad potential of NIR QDs for various biomedical imaging applications.