Ultra-Small Air-Stable Triplet-Triplet Annihilation Upconversion Nanoparticles for Anti-Stokes Time-Resolved Imaging

Bolong Zhang; Kieran D Richards; Beatrice E Jones; Abigail R Collins; Rosie Sanders; Sarah R Needham; Pu Qian; Amoghavarsha Mahadevegowda; Caterina Ducati; Stanley W Botchway; Rachel C Evans

doi:10.1002/anie.202308602

Ultra-Small Air-Stable Triplet-Triplet Annihilation Upconversion Nanoparticles for Anti-Stokes Time-Resolved Imaging

Angew Chem Int Ed Engl. 2023 Nov 20;62(47):e202308602. doi: 10.1002/anie.202308602. Epub 2023 Sep 19.

Authors

Bolong Zhang^{1

2}, Kieran D Richards¹, Beatrice E Jones^{1

3}, Abigail R Collins¹, Rosie Sanders⁴, Sarah R Needham⁴, Pu Qian⁵, Amoghavarsha Mahadevegowda^{1

6}, Caterina Ducati^{1

6}, Stanley W Botchway⁴, Rachel C Evans¹

Affiliations

¹ Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK.
² CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China.
³ Diamond Light Source, Didcot, Oxfordshire, OX11 0QX, UK.
⁴ Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Oxfordshire, OX11 0QX, UK.
⁵ Materials and Structural Analysis, Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG, Eindhoven, The Netherlands.
⁶ The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot, UK.

Abstract

Image contrast is often limited by background autofluorescence in steady-state bioimaging microscopy. Upconversion bioimaging can overcome this by shifting the emission lifetime and wavelength beyond the autofluorescence window. Here we demonstrate the first example of triplet-triplet annihilation upconversion (TTA-UC) based lifetime imaging microscopy. A new class of ultra-small nanoparticle (NP) probes based on TTA-UC chromophores encapsulated in an organic-inorganic host has been synthesised. The NPs exhibit bright UC emission (400-500 nm) in aerated aqueous media with a UC lifetime of ≈1 μs, excellent colloidal stability and little cytotoxicity. Proof-of-concept demonstration of TTA-UC lifetime imaging using these NPs shows that the long-lived anti-Stokes emission is easily discriminable from typical autofluorescence. Moreover, fluctuations in the UC lifetime can be used to map local oxygen diffusion across the subcellular structure. Our TTA-UC NPs are highly promising stains for lifetime imaging microscopy, affording excellent image contrast and potential for oxygen mapping that is ripe for further exploitation.

Keywords: Fluorescence; Lifetime Imaging Microscopy; Nanoparticles; Triplet-Triplet Annihilation; Upconversion.

Abstract

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