Multitunable Hydrogels

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Science  11 Oct 2013:
Vol. 342, Issue 6155, pp. 165
DOI: 10.1126/science.342.6155.165-b

Hydrogels, consisting of water-swollen crosslinked polymer chains, have proved a versatile platform for creating an artificial environment for cells. Through dynamic crosslinking, it is possible to spatially change the physical and chemical properties within the gel or to allow for drug delivery or degradation of the gel. One challenge is to find routes that allow for either modification of the mechanical properties of the gel or of its local chemistry, without affecting the other. Gramlich et al. show that this is possible for a system based on hyaluronic acid, which is a component of native extracellular matrix that has been functionalized using norborene groups. Gelation occurs through the reaction of the norborene groups with a di-thiol, but only a few connections were needed to form the gel. Thus, remaining pendant norborene groups were available for secondary reactions, either to tune the gel's mechanical properties by using additional di-thiol linkages or by using mono-thiol groups to change the local chemistry by linking in additional molecules such as peptides. For example, the compressive modulus ranged from 1 to 70 kPa, depending on the extent of crosslinking for the same overall norborene content. Using reactions controlled by ultraviolet light made it possible to pattern the gels with either spatial or temporal control of the patterns.

Biomaterials, 10.1016/j.biomaterials.2013.08.089 (2013).

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