A photochromic upconversion nanoarchitecture: towards activatable bioimaging and dual NIR light-programmed singlet...

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Photochemistry

Background:

• Precise control of singlet oxygen (¹O₂) generation is crucial for biological studies and precision medicine.
• Existing methods for ¹O₂ generation often lack spatiotemporal control.
• Developing advanced nanomaterials is key to overcoming these limitations.

Purpose of the Study:

• To design and synthesize a novel nanoarchitecture for dual near-infrared (NIR) light-programmable ¹O₂ generation.
• To enable on-demand activation of ¹O₂ production for bioimaging and photodynamic therapy.
• To shift ¹O₂ generation into the therapeutic window for enhanced efficacy.

Main Methods:

• Synthesis of mesoporous silica-coated upconversion nanoparticles (UCNPs).
• Covalent embedding of porphyrin photosensitizers (PSs) within silica walls.
• Loading of NIR-responsive diarylethene (DAE) photochromic switches into nanopores.

Main Results:

• UCNPs efficiently generate ¹O₂ upon 980 nm NIR light irradiation via energy transfer to PSs.
• ¹O₂ generation is switchable using 808 nm NIR light to control DAE photochromic switches.
• Demonstrated *in vitro* and *in vivo* NIR light-mediated activation for bioimaging and photodynamic therapy.

Conclusions:

• The developed nanoarchitecture offers precise, dual NIR light-programmable control over ¹O₂ generation.
• This system holds significant potential for advanced bioimaging and targeted photodynamic therapy.
• The NIR light-mediated on-demand activation strategy represents a breakthrough in controllable therapeutic approaches.