Photostable and efficient upconverting nanocrystal-based chemical sensors

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Optical Sensing

Background:

• Optical sensors for chemical signaling require brightness, stability, and sensitivity.
• Lanthanide-doped upconverting nanoparticles (UCNPs) offer background-free, photobleaching-resistant imaging.
• UCNPs lack inherent sensing ability, necessitating pairing with organic fluorophores for biosensing.

Purpose of the Study:

• To develop stable UCNP-fluorophore conjugates with efficient upconverted energy transfer (UET) for chemical sensing.
• To enhance the photostability and emission of UCNP-based biosensors.
• To create a platform for NIR-responsive biosensors for cell signaling analysis.

Main Methods:

• Synthesized Yb3+- and Er3+-doped UCNP-fluorophore conjugates.
• Investigated upconverted energy transfer (UET) efficiencies and photostability.
• Utilized inert shells to enhance emission and UET efficiency.
• Assessed chemical stability of covalently attached versus directly coordinated fluorophores.

Main Results:

• Achieved UET efficiencies up to 88% in UCNP-fluorophore conjugates.
• Demonstrated 100-fold greater photostability by UET excitation compared to direct excitation.
• Thin inert shells enhanced overall emission without compromising UET efficiency.
• Covalently attached sensors exhibited superior chemical stability.

Conclusions:

• UCNP-fluorophore conjugates provide a robust platform for highly photostable and sensitive optical biosensors.
• The developed UCNP-based hybrids significantly improve the longevity of organic fluorophores for chemical sensing.
• This approach enables the development of NIR-responsive biosensors for quantifying critical cell signaling dynamics.