Highly Photostable Near-IR-Excitation Upconversion Nanocapsules Based on Triplet–Triplet Annihilation for in Vivo Bioimaging Application

• Published in: ACS applied materials & interfaces Vol. 10; no. 12; pp. 9883 - 9888
• Main Authors: Liu, Qian, Xu, Ming, Yang, Tianshe, Tian, Bo, Zhang, Xinglin, Li, Fuyou
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 28.03.2018
• Subjects: Animals; image analysis; irradiation; light intensity; Nanocapsules; photostability; Singlet Oxygen; solvents; soybean oil; toluene; triplet−triplet annihilation; upconversion luminescence; enhanced photostability; NIR; bioimaging
• ISSN: 1944-8244; 1944-8252; 1944-8252
• DOI: 10.1021/acsami.7b17929

Triplet–triplet-annihilation-based upconversion (TTA-UC) imaging boasts a low-excitation irradiance and an uncanny lack of autofluorescence interference. Because of these promising features, this approach has been the subject of intensifying investigation. Despite the ideal features, the classical approach of TTA-UC imaging suffers from some crucial drawbacks. A major deficiency of the system lies within its poor photostability, especially for a near-IR-excitation system. Here we report a reduction strategy to improve the TTA-UC photostability. The poor photostability of TTA-UC can be attributed to singlet oxygen generation by the sensitizer under irradiation. We control the singlet oxygen by including a reductive solvent, which consumes the singlet oxygen, thereby improving the TTA-UC photostability. We also prepared TTA-UC nanocapsules with reductive solvent soybean oil inside. In comparison to nonreductive solvents such as toluene, our system shows a significant enhancement to the TTA-UC photostability. The prepared TTA-UC nanocapsules were then used for whole-animal deep imaging with a high signal-to-noise ratio.