Near-Infrared to Visible Photon Upconversion with Gold Quantum Rods and Aqueous Photo-Driven Polymerization

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Triplet-triplet annihilation upconversion (TTA-UC) converts near-infrared (NIR) to visible light, crucial for energy and biomedical applications.
• Efficient NIR sensitizers are essential for TTA-UC but remain a significant challenge.

Purpose of the Study:

• To develop a high-performance photosensitizer for NIR-to-visible TTA-UC.
• To create an aqueous-compatible TTA-UC system for advanced photopolymerization and biomedical applications.

Main Methods:

• Synthesized an atomically precise gold quantum rod, Au42(PET)32, as an NIR sensitizer.
• Paired the gold quantum rod with TES-ADT as an annihilator for TTA-UC.
• Encapsulated Au42/TES-ADT upconversion nanodroplets within a silica shell to create Au42/TES-ADT@SiO2 nanoparticles (NPs).

Main Results:

• Achieved a 6.7% quantum yield for NIR-to-visible TTA-UC.
• Observed a 0.5 eV anti-Stokes shift and a low threshold intensity of 90 mW/cm2.
• Demonstrated efficient photoinduced atom-transfer radical polymerization (photo-ATRP) and hydrogel formation in water using the silica-coated NPs.

Conclusions:

• Atomically precise gold quantum rods serve as effective photosensitizers for NIR-to-visible TTA-UC.
• The developed silica-encapsulated NPs provide aqueous compatibility for TTA-UC applications.
• This system presents a versatile platform for NIR-driven photopolymerization, solar energy utilization, and noninvasive biomedical applications.