Results and discussion
The major problem in obtaining polyester cellular scaffolds is their
appropriate porosity and morphology of their pores. In the inversion
phase method, it is not possible to obtain correct porous surfaces and
large, interconnected pores inside the scaffold, without using pore
precursors. Classic pore precursors, i.e. polymers
(polyvinylpyrrolidone, polyethylene glycol) or crystals of salt that are
being added into the polymer’s solution and then washed away from
coagulated scaffolds – do not give the desired effect.[56] The
pores which are formed this way are usually not large enough (over a
dozen µm), unevenly distributed, and poorly interconnected.[57]
The scaffold for the culture of chondrocytes should have large (at least
30–40 µm) interconnected pores, distributed within the entire volume of
the structure.[58] One of the scaffold surfaces must have high
porosity, allowing for penetration of cultured cells inside the
scaffold. On the other hand, the other surface should contain small,
rare pores to prevent the cells from ”falling out” from the polymeric
scaffold.[59]
In the presented examinations, the scaffolds of poly-L-lactide were
obtained without using any pore precursors and with the PVP or both PVP
and Pluronic® as the classic pore precursors.
If no pore precursors have been used, then small and round pores having
a diameter of 3–6 µm were observed (Fig. 1) on the bottom surface of
the scaffold prepared from PLLA, from the side of glass base. The upper
surface was more porous than the bottom one. Moreover, there were
larger, round pores 5–10 µm in diameter, and the rest of the pores were
covered with a thin covering layer preventing the cells from penetrating
inside the scaffold. In the cross-section of the scaffold, there were
some oval pores 5–15 µm in size and the wall thickness of 1–2 µm.