Super-Resolution Mapping of Single Nanoparticles inside Tumor Spheroids

Area of Science:

• Biomedical Optics
• Nanotechnology
• Cancer Research

Background:

• Cancer spheroids are valuable in vitro models for studying tumor physiology and drug efficacy.
• Light microscopy is limited in deep-penetration imaging of dense spheroids due to scattering and absorption.
• Visualizing nanoparticles within spheroids is crucial for understanding drug delivery and release.

Purpose of the Study:

• To develop a super-resolution imaging technique for mapping single nanoparticles deep within cancer spheroids.
• To overcome the limitations of conventional microscopy in scattering and absorptive biological tissues.
• To enable real-time monitoring of nanoparticle behavior and drug release in 3D multicellular environments.

Main Methods:

• Utilized a nondiffractive Bessel beam (980 nm) for excitation, leveraging its self-healing property.
• Employed upconversion nanoparticles (UCNPs) with nonlinear optical responses for near-infrared (NIR) excitation and emission.
• Developed a novel nanoscopy modality achieving high resolution by minimizing light loss within the spheroid.

Main Results:

• Achieved a super-resolution imaging modality with a spatial resolution of 37 nm (1/26th of the excitation wavelength).
• Successfully mapped single nanoparticles located up to 55 µm deep within a cancer spheroid.
• Demonstrated a resolution of 98 nm for nanoparticle mapping at depth within the spheroid.

Conclusions:

• The developed nanoscopy technique provides a breakthrough for deep-tissue imaging in complex biological models.
• This method allows for precise tracking of single nanoparticles and monitoring of drug release in 3D multicellular environments.
• Offers a powerful tool for advancing cancer research, drug development, and personalized medicine.