Manipulating energy migration within single lanthanide activator for switchable upconversion emissions towards...

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Photochemistry

Background:

• Phototherapy efficacy is limited by shallow tissue penetration of UV/visible light.
• Near-infrared (NIR) to visible light transducers like upconversion nanoparticles (UCNPs) offer deeper tissue penetration.
• Current UCNPs lack orthogonal emissions for precise, programmable biological control due to activator crosstalk.

Purpose of the Study:

• To develop UCNPs with orthogonal emission profiles for programmable phototherapy.
• To utilize cross-relaxation (CR) in lanthanide ions for wavelength-tunable dual emissions.
• To demonstrate precise control of cellular functions using these novel UCNPs.

Main Methods:

• Synthesized UCNPs doped with a single activator ion (Er3+).
• Manipulated energy migration via cross-relaxation by tuning excitation wavelength (980 nm vs. 808 nm).
• Demonstrated orthogonal red and green light emissions from the same UCNP.
• Programmed activation of VChR1 and Jaws ion channels in cells for membrane polarization control.

Main Results:

• Achieved orthogonal red and green emissions from Er3+-doped UCNPs by adjusting excitation wavelength.
• Demonstrated wavelength-dependent manipulation of UCNP emissions, avoiding multi-doping and multi-shell complexity.
• Successfully controlled cellular membrane polarization through synergistic activation of two light-gated ion channels.
• Validated the approach for cardiac pacing applications.

Conclusions:

• Cross-relaxation offers a novel strategy for engineering UCNPs with tunable, orthogonal emissions.
• This approach simplifies UCNP synthesis and enhances control over phototherapeutic applications.
• The developed UCNPs provide a versatile platform for advanced optogenetic tools and deep-tissue phototherapy.