Temporal Multiplexed in Vivo Upconversion Imaging.

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Materials Science

Background:

• Upconversion nanoparticles (UCNPs) convert near-infrared (NIR) light to visible luminescence, crucial for bioimaging.
• Multiplexed in vivo imaging is limited by the scarcity of UCNP luminescence bands that penetrate deep tissues.

Purpose of the Study:

• To develop a novel approach for multiplexed upconversion in vivo imaging using time-domain discrimination.
• To overcome limitations of existing UCNP luminescence bands for deep tissue penetration.

Main Methods:

• Engineered tetradomain nanostructures to control energy migration and upconversion processes.
• Utilized time-domain discrimination of NIR luminescence (808 nm) with distinct lifetimes.
• Administered aqueous UCNPs intravenously and subcutaneously into Kunming mice.

Main Results:

• Achieved high quantum yield upconversion luminescence (max ≈ 6.1%) with precisely controlled lifetimes spanning two orders of magnitude (78–2157 μs).
• Demonstrated high-contrast, lifetime-colored imaging of UCNPs in mouse liver and subcutaneous tissues.
• Enabled multicolor presentation of deciphered images using optical patterns and defined lifetimes.

Conclusions:

• The temporal multiplexed upconversion approach enables advanced in vivo imaging and anticounterfeiting.
• This method has significant implications for high-throughput biosensing, volumetric displays, and diagnosis and therapy.