Lanthanide Tri-Doping Engineered Upconversion Emissions under Dual-Wavelength Excitation toward High-Resolution...

Area of Science:

• Nanoparticle science
• Optical imaging
• Materials chemistry

Background:

• Lanthanide-doped upconversion nanoparticles (UCNPs) offer photostable emissions for optical probes.
• Dual-wavelength excitation tailors UCNP emissions but faces challenges in emission depletion due to competitive excitation.
• Achieving controlled emission depletion is crucial for advanced imaging applications.

Purpose of the Study:

• To develop a novel strategy for effective upconversion emission depletion in lanthanide-doped nanoparticles.
• To overcome limitations of competitive dual-wavelength excitation in achieving emission quenching.
• To demonstrate a new approach for high-resolution microscopic imaging using UCNPs.

Main Methods:

• A lanthanide tridoping strategy was employed, incorporating a re-excitation enabled emission depletion (REED) process.
• REED involves re-exciting lanthanide ions to higher energy levels, followed by codopant-mediated cross-relaxation (CR) and energy transfer (ET) to depopulate these levels.
• The CR/ET-REED approach was tested on Er³⁺-Yb³⁺-Ln³⁺ tridoped nanoparticles under 795 nm excitation and 1140 nm re-excitation.

Main Results:

• The CR/ET-REED approach significantly depleted green upconversion emissions in tridoped nanoparticles, increasing efficiency from 19.4% to 48.5%.
• High-resolution microscopic imaging with sub-250 nm resolution was achieved using the developed nanoparticles under dual-wavelength excitation.
• The study demonstrated a synergistic effect of CR/ET pathways and REED in population depletion.

Conclusions:

• The CR/ET-REED strategy provides a generalizable method for developing advanced UCNP-based imaging probes with emission depletion capabilities.
• This work represents a significant advancement in UCNP technology, shifting towards tridoped systems for enhanced functionality.
• The developed nanoparticles enable high-resolution imaging, overcoming previous limitations in emission control.