Printable Hydrogels

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Science  04 Apr 2014:
Vol. 344, Issue 6179, pp. 10
DOI: 10.1126/science.344.6179.10-b

Hydrogels consist of highly water-swollen cross-linked polymer networks, which make them of interest as materials for storing and delivering cells. However, because they are soft and squishy, it is difficult to shape or form the hydrogels in the way that you might construct pieces from more solid materials. One hydrogel system used for tissue engineering is based on gelatine, a low-immune-response, enzymatically degradable protein, which is cross-linked with methacryalmide groups. Through the addition of gellan gum, an FDA-approved food additive, Melchels et al. show that the gelatinmethacrylamide can be made stiff enough to be used in additive printing processes for making complex shapes. The chains in gellan gum bind through ionic bonding, so by adjusting the salt concentration, it is possible to tune the rheological properties to allow for shear thinning and yield stress, which are necessary for depositing material at controlled places. The salt concentrations, however, were lower than those found in physiological conditions, so the authors replaced some of the phosphate-buffered saline with the sugar mannose to provide a controlled osmotic-pressure environment to allow for the inclusion of cells within the gel material.

J. Mater. Chem. B 10.1039/c3tb21280g (2014).

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