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6 Skin, The Body’s Largest Organ

Figure 6.13: Drug delivery with smart materials (adapted from [34]).

start flowing. It will flow past a catalyst, which will start polymerization, forming new

polymer in the crack, thus “healing” the matrix. In a lot of cases, healing additionally

requires heat or light, since most polymerization initiators require heat or light for acti-

vation. A lot of research has been performed to optimize the outer capsule membrane,

the distribution of catalyst and capsules in the matrix, the kinetics of the healing poly-

merization, and the strength recovery for the material [38, 40]. Analogous work has been

done for supramolecular systems, i. e., systems based on intermolecular forces instead

of covalent bonds [41], as well as for nanostructured materials [42].

For biomaterials that will be used in medicine, it is important that the material used

is a hydrogel so that it can take advantage of water-based transport. At the same time,