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. Author manuscript; available in PMC: 2013 May 13.
Published in final edited form as: Chem Rev. 2008 Nov;108(11):10.1021/cr800443h. doi: 10.1021/cr800443h

Figure 46.

Figure 46

Replication of the sea urchin spine by micromolding PILP phase in an inverse replica of the urchin spine. (a) Monomer of 2-hydroxyethyl methacrylate (HEMA) was polymerized within a bleached spine of the urchin Arbacia punctulata, to create the poly(HEMA) inverse replica, which looks very similar to the original spine microstructure (shown in Figure 3b & c). (b) Higher magnification shows the bicontinuous microstructure, which is what allows for infiltration of polymer to make the replica, followed by removal of the original biomineral, and subsequent infiltration of the mineral precursor, to mold a replica. (c) Energy dispersive spectroscopy (EDS) shows the replica is all organic, once the original mineral of the spine has been removed, leaving behind a pure poly(HEMA) scaffold. (d) Photographic comparison between the Poly(HEMA) scaffold, replicas, and the original spine, to demonstrate dimensional changes that occur when the hydrogel scaffold is dried. The original polymer scaffold is shown in (A); while (B) shows a scaffold containing crystals grown via the conventional process; while (C) shows the scaffold mineralized with the PILP process; and (D) shows an original urchin spine, which is purple from impurities typical of the purpuratos species. Note, the dimensions of specimen (B) are much smaller because the crystals did not infiltrate and fill space in the scaffold, so the poly(HEMA) hydrogel collapsed upon drying. Only a few crystals nucleated on the surface of the scaffold, which can be seen in the SEM in (e). On the other hand, the dimensions of the original spine were retained for specimen (C) because the precursor phase fully infiltrated the porous scaffold, and replicated the morphology of the spine. (f) The molded replica of filled space and produced a similar morphology, but had rougher surfaces, presumably because of the hydrogel nature of the template, and was not single crystalline, due to multiple nucleation events. (Reprinted with permission from ref 222. Copyright 2006 American Chemical Society and American Institute of Chemical Engineers.)