Photon Upconversion Hydrogels for 3D Optogenetics. (4th June 2021)

• Record Type: Journal Article
• Authors: Meir, Rinat; Hirschhorn, Tal; Kim, Sungsoo; Fallon, Kealan J.; Churchill, Emily M.; Wu, Dino; Yang, Hee Won; Stockwell, Brent R.; Campos, Luis M.
• Is Part Of: Advanced functional materials. Volume 31:Number 31(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-04
• Subjects: biomaterials -- hydrogels -- optogenetics -- photon upconversion -- triplet–triplet annihilation; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202010907
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: The ability to optically induce biological responses in 3D has been dwarfed by the physical limitations of visible light penetration to trigger photochemical processes. However, many biological systems are relatively transparent to low‐energy light, which does not provide sufficient energy to induce photochemistry in 3D. To overcome this challenge, hydrogels that are capable of converting red or near‐IR (NIR) light into blue light within the cell‐laden 3D scaffolds are developed. The upconverted light can then excite optically active proteins in cells to trigger a photochemical response. The hydrogels operate by triplet–triplet annihilation upconversion. As proof‐of‐principle, it is found that the hydrogels trigger an optogenetic response by red/NIR irradiation of HeLa cells that have been engineered to express the blue‐light sensitive protein Cry2olig. While it is remarkable to photoinduce the clustering of Cry2olig with blanket NIR irradiation in 3D, it is also demonstrated how the hydrogels trigger clustering within a single cell with great specificity and spatiotemporal control. In principle, these hydrogels may allow for photochemical control of cell function within 3D scaffolds, which can lead to a wealth of fundamental studies and biochemical applications. Abstract : Upconversion hydrogels are developed from modular chromophores that can convert low energy near‐IR light to high energy visible blue light by triplet–triplet annihilation upconversion. Engineered cells encapsulated within the hydrogels are triggered by the locally upconverted light, showing an optogenetic response on‐demand in 3D with spatial resolution.