A 25 micron-thin microscope for imaging upconverting nanoparticles with NIR-I and NIR-II illumination

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Medical Imaging

Background:

• Minimally invasive surgery requires miniaturized imaging for small cavities.
• Current optical imagers have bulky components (lenses, filters, fibers), limiting maneuverability.
• Existing imagers are typically centimeter-scale, hindering integration with surgical tools.

Purpose of the Study:

• To develop a miniaturized, high-resolution imaging technology for intraoperative use.
• To integrate upconverting nanoparticles (aUCNPs) with a thin CMOS imager for enhanced visualization.
• To demonstrate the feasibility of this technology in preclinical tumor imaging.

Main Methods:

• Engineered INSITE (Immunotargeted Nanoparticle Single-Chip Imaging Technology) combining aUCNPs and a 25-micron thin CMOS imager.
• Synthesized and characterized core/shell aUCNPs for visible emission under NIR-I and NIR-II photoexcitation.
• Performed intratumoral injection of aUCNPs into prostate tumors in mice and subsequent imaging with INSITE.

Main Results:

• INSITE achieved time-resolved imaging of aUCNPs with radiative lifetimes of 600 μs - 1.3 ms.
• Core/shell NaEr$_{0.6}$Yb$_{0.4}$F4 aUCNPs provided the highest signal under 980 nm and 1550 nm excitation.
• Demonstrated 55 μm spatial resolution and a signal-to-background ratio of 9 in tumor imaging.

Conclusions:

• INSITE provides a 25 μm-thin, planar imaging platform for tumor visualization using aUCNPs.
• The technology supports both NIR-I and NIR-II excitation and is scalable for integration with surgical tools.
• INSITE enables seamless integration with robotic surgery for enhanced precision and maneuverability.