Abstract
Click chemistry provides extremely selective and orthogonal reactions that proceed with high efficiency and under a variety of mild conditions, the most common example being the copper(I)-catalysed reaction of azides with alkynes1,2. While the versatility of click reactions has been broadly exploited3,4,5, a major limitation is the intrinsic toxicity of the synthetic schemes and the inability to translate these approaches into biological applications. This manuscript introduces a robust synthetic strategy where macromolecular precursors react through a copper-free click chemistry6, allowing for the direct encapsulation of cells within click hydrogels for the first time. Subsequently, an orthogonal thiol–ene photocoupling chemistry is introduced that enables patterning of biological functionalities within the gel in real time and with micrometre-scale resolution. This material system enables us to tailor independently the biophysical and biochemical properties of the cell culture microenvironments in situ. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gels with ideal structures that can be photopatterned, and all in the presence of cells.
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Acknowledgements
The authors would like to thank C. Bertozzi and J. Baskin for their initial donation of DIFO3, R. Shoemaker for his assistance with magic-angle spinning NMR, A. Kloxin and B. Fairbanks for their discussions on photopatterning, A. Aimetti for communication on peptide work and C. Kloxin for his critiques in the preparation of this manuscript. Thanks are also given to HHMI and the Janelia Farm Research Campus for support in the use of their two-photon confocal microscope. Fellowship assistance to C.A.D. was awarded by the US Department of Education’s Graduate Assistantships in Areas of National Need program and the National Institutes of Health (T32 GM-065103).
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B.D.P., C.A.D. and K.S.A. developed the material concept, C.A.D., B.D.P. and K.S.A. designed the experiments, C.A.D. carried out the experiments, and C.A.D. and K.S.A. composed the manuscript.
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DeForest, C., Polizzotti, B. & Anseth, K. Sequential click reactions for synthesizing and patterning three-dimensional cell microenvironments. Nature Mater 8, 659–664 (2009). https://doi.org/10.1038/nmat2473
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DOI: https://doi.org/10.1038/nmat2473
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