![photolinker ii photolinker ii](https://i.stack.imgur.com/hY8aA.png)
These PEG-based materials are useful for probing the dynamic influence of cell-cell and cell-material interactions on cell function in 2D or 3D. This comprehensive protocol is useful for controlling peptide presentation and substrate modulus during cell culture on or within an elastic matrix.
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Hydrogel degradation occurs on-demand, in seconds to minutes, with user-directed light exposure. Preparation of the sterile solutions for hydrogel fabrication takes hours, while the reaction to form the final hydrogel is complete in minutes. In this protocol, synthesis and purification of the photodegradable monomers take approximately 2 weeks, but can be substantially shortened by purchasing the o-nitrobenzylether precursor. Degradation is readily achieved with cytocompatible wavelengths of low intensity flood irradiation (365 to 420 nm) in minutes or with highintensity laser irradiation (405 nm) in seconds. Cell-material interactions can be probed in 2D or 3D by spatiotemporally controlling the gel microenvironment, which allows unique experiments to be performed to monitor cell response to changes in their niche. Hydrogels are synthesized with the photodegradable crosslinker in the presence or absence of cells, allowing direct encapsulation or seeding on surfaces. Here, we provide coupling procedures to PEG- bis-amine to form a photodegradable crosslinker or to the fibronectin-derived peptide RGDS to form a photoreleasable tether. The materials are created by synthesizing an o-nitrobenzylether-based photodegradable monomer that can be coupled to primary amines. The cytocompatible chemistry and degradation process enable dynamic, tunable changes for applications in 2D or 3D cell culture.
![photolinker ii photolinker ii](https://macx.ws/uploads/posts/2015-06/1434624762_emulsion_02.png)
We describe a detailed procedure to create photolabile, poly(ethylene glycol)-based (PEG) hydrogels and manipulate material properties in situ.