Highly Sensitive Laser Scanning of Photon-Upconverting Nanoparticles on a Macroscopic Scale

Area of Science:

• Biomedical imaging
• Nanotechnology
• Analytical chemistry

Background:

• Conventional fluorescent dyes suffer from background interference and limited dynamic range in macroscopic imaging.
• Photon-upconverting nanoparticles (UCNPs) offer unique optical properties for advanced bioimaging applications.
• Optimizing UCNP-based systems is crucial for achieving sensitive and quantitative detection in complex biological samples.

Purpose of the Study:

• To optimize an upconversion laser scanner for background-free macroscopic imaging using photon-upconverting nanoparticles (UCNPs).
• To evaluate the sensitivity and dynamic range of UCNP-based imaging compared to conventional fluorescent dyes.
• To demonstrate the application of UCNP imaging for sensitive and quantitative detection of disease markers.

Main Methods:

• Development and optimization of a collimated 980 nm laser scanner for UCNP excitation.
• Characterization of UCNP detectability and linear dynamic range.
• Agarose gel electrophoresis to separate UCNPs and dye-doped silica shells, followed by scanning with both conventional and upconversion scanners.
• Application of upconversion imaging to lateral flow test strips for disease marker detection.

Main Results:

• The optimized upconversion laser scanner achieved background-free macroscopic imaging.
• As few as 2000 UCNPs were detectable, with a linear dynamic range exceeding 5 orders of magnitude.
• Independent detection of both UCNPs and dye-doped silica shells was demonstrated.
• Sensitive and quantitative detection of a Schistosoma marker on lateral flow test strips was achieved using upconversion imaging.

Conclusions:

• Upconversion laser scanning with UCNPs provides a superior alternative to conventional fluorescence imaging for macroscopic applications.
• The high sensitivity and wide dynamic range of UCNP imaging enable precise detection of low-abundance analytes.
• This technology holds significant potential for sensitive and quantitative diagnostics of infectious diseases and other biomarkers.