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Upconverting nanoparticles (UCNPs) convert near-infrared (NIR) light to UV or visible light that can trigger photoreactions of photosensitive compounds. This process is called UCNP-assisted photochemistry. In this talk, I will present the use of UCNPs to assist photosubstitution of Ru complexes.[1-5] We demonstrate UCNPs converted 974 nm light at an intensity of 0.35 W/cm2 to blue light that triggered the cleavage of photocleavable Ru complexes. This light intensity is lower than the maximum permissible exposure of skin and it is the lowest intensity reported for UCNP-assisted photochemistry. Overheating problems of NIR light were minimized and photodamage to biomaterials was prevented at such a low light intensity. We used this UCNP-assisted photochemistry for drug delivery, patterning of biomaterials, and control pH. For drug delivery, mesoporous silica coated UCNPs were loaded with the anticancer drug doxorubicin and grafted with Ru complexes as photoactive molecular valves. NIR light passed through tissue and induced the cleavage of Ru complexes and the release of doxorubicin. The released doxorubicin inhibited the growth of cancer cells. To pattern proteins using NIR light, proteins and an upconverting-nanoparticle-decorated substrate were linked via photocleavable Ru complexes. The substrate was irradiated using NIR light with a photomask. In the exposed areas of the substrate, upconverting nanoparticles converted the NIR light into blue light, which induced cleavage of the Ru complexes and release of the proteins.
References
[1] Z. Chen, S. He, H.-J. Butt, S. Wu, Adv. Mater., 2015, 27, 2203.
[2] S. Wu, H.-J. Butt, Adv. Mater. 2016, 28, 1208.
[3] S. He, K. Krippes, S. Ritz, Z. Chen, A. Best, H.-J. Butt, V. Mailänder, S. Wu, Chem. Commun., 2015, 51, 431.
[4] Z. Chen, W. Sun, H.-J. Butt, S. Wu, Chem. Eur. J., 2015, 21, 9165.
[5] Z. Chen, Y. Xiong, R. Etchenique, S. Wu, Chem. Commun. 2016, 52, 13959.
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