Fig. 1. SEM photomicrographs of PLLA, PCLA, PCL scaffolds obtained with
classic pore precursor.
Round pores were having a diameter of 5–15 µm. It was observed on the
bottom surface of the scaffold prepared from PLLA with the addition of
PVP as the pore precursor. The upper surface was more porous than the
bottom one. Pores at this surface were round and of a larger diameter
(2–20 µm) and other pores were covered with a thin covering layer.
Numerous oval pores of a size of 5–15 µm were seen in the cross-section
of the scaffold. Between them were also larger pores of the size of
20–30 µm.
Moreover, smaller pores of the size under 5 µm were observed in the
walls of these pores (1–2 µm thick). This is a critical feature of the
culture of the cells as perforations of walls of inner pores allow for
the migration of nutrients and metabolites. On the bottom scaffold
surface obtained from PLLA with the PVP or Pluronic® addition round
pores of a diameter of 10–15 µm was observed. Microscopic pores of the
size less than 1 µm were observed between the bigger ones. The majority
of pores were covered with a thin covering layer. Rare, irregularly
distributed pores having 10–40 µm in diameter were seen on the upper
surface. In the cross-section of the scaffold, there were oval pores of
the size of 10–15 µm. Larger pores, having 30–50 µm in diameter were
present between them. As in previous cases, the inner walls of pores had
a thickness of 1–2 µm.
Considering that the addition of classic pore precursors didn’t allow
for obtaining the scaffolds of a proper morphology, because pores were
still too small and weakly interconnected – an unconventional approach
has been adopted. The previous studies have shown that the use of
polymeric non-wovens as non-classic pore precursors leads to the forming
of scaffolds of a desirable morphology [58–62]. Cellulose-based
non-wovens, despite their high efficiency, were characterized by
irregular structure. Moreover, their removal from the structure of the
scaffold required several weeks.