STEM CELLS AND NANOTECHNOLOGY IN TISSUE ENGINEERING AND REGENERATIVE MEDICINE - Micro and Nanotechnologies in Engineering Stem Cells and Tissues - page 13

FIGURE 1.3 Scaffolds created using thermally induced phase separation derived from three-
dimensional reconstructions of computed tomography (CT) scans. (a) Human ear reconstructed
from histological sections and (b) the resulting nanofiber scaffold (scale bar ¼ 10mm). (c)
Human mandible reconstruction from CT scans and (d) resulting nanofiber scaffold (scale
bar 10mm). (e) Scanning electronmicrographs showing interconnected spherical pores within

mandible segment (scale bar

¼

m) and (f) nanofiber pore morphology within a single pore
(scale bar ¼ 5 m m). Reprinted with permission from Ref. [67].

500 m

¼

the network through hydrogen bonds and include regions that contain charged amino
acids that control the solubility of the PAs under different pH conditions. 70 These
structural features are particularly useful for generating injectables that are prepared
under conditions that prevent self-assembly but are induced to undergo rapid self-
assembly into a nanofiber network upon exposure to physiological pH. Bioactive
factors such as DNA, drugs, or other proteins may be mixed into the unassembled
solution for encapsulation into the fibers upon assembly and then released into the
surrounding environment upon degradation.
Self-assembly of PAs can be used to generate a large variety of nanostructures
with specifically tuned biochemical and degradation properties. For example, to
promote mineral deposition for bone formation, phosphoserine residues have been