Page 50 - IJB-9-1

International Journal of Bioprinting Effect of ionic crosslinking on composite membranes

stability of alginate-based composite bioscaffolds with the T dmax of the alginate-based composite bioscaffolds
SFDDS (Figure 8). The maximum pyrolysis temperature exhibited a temperature lower than 300°C, which would
(T dMax) of the alginate was ca. 250°C. In this study, be due to the non-ionic cross-linked structure and weak
the supercritical fluids-decellularized dermal-based cross-linked structure (Figures 7A, B and 8A, B). DTG
bioscaffold (SFDDS) that was used to prepare alginate- curves would provide useful information to study the
based composite bioscaffolds might have relatively high effect of Ca ion penetration on structural stability and
2+
thermal stability and good structural stability. The Tdmax thermal stability. Different microstructures, such as (I),
of the alginate-based composite bioscaffolds was higher (II),(III), and (IV) (Figure 7A and B), might be proposed
than 300°C, indicating that the bioscaffolds become heat- depending on the TGA and DTG results, which exhibited
resistant biomaterial, following the introduction of SFDDS maximum pyrolysis temperatures in different temperature
molecules after a suitable crosslinking reaction (e.g., stages, such as the T dmax peak of ca. 90°C at the stage of

soaking time > 5 min), which is suitable for bioprinting 50 – 200°C, the T dmax peak of ca. 270°C at the stage of 200 –
applications (Figure 8C-E). If the soaking time is too short, 300°C, the T dmax peak of ca. 360°C at the stage of 300 –
400°C, and the T dmax peak of ca. 460°C at the stage of 400
A – 500°C. Formations of specific microstructures would
be reflected in T dmax peaks of DTG curves. Before ionic
crosslinking reaction, a series of porous alginate-based
composite bioscaffolds could be lyophilized and obtained.
Furthermore, the resulting alginate-based composite
bioscaffolds were ionically cross-linked with CaCl (aq) to
2
obtain cross-linked alginate-based composite bioscaffolds
B
through Ca ion penetration. The Ca ions could
2+
2+
penetrate into the porous microstructures during the
different soaking time. The Ca ions could not penetrate
2+
into the porous microstructures completely during the
short soaking time (Figure 7A). Most of microstructures
would be proposed as microstructure I and microstructure
C II. The microstructure III might be formed with the
increase of soaking time in an aqueous solution of CaCl .
2
The heat resistance would be enhanced.
The T dmax of cross-linked composite bioscaffolds
was lower than 400°C. Even most of ALG molecules
could be associated with SFDDS, as shown in
D Figure 8D and E. Compared with SFDDS, cross-linked
composite bioscaffolds showed relatively high T dmax of
360 – 380°C because of the formation of microstructure
II and microstructure III (380°C). The T dmax of SFDDS
was observed at 340°C (Figure 9A). The increased T dmax
might be resulted from enhanced interaction among SFDDS
and ALG segments. Compared with alginate-based ALG
E bioscaffold, the T dmax of ALG molecules was observed at
240°C (Figure 9B). The cross-linked alginate-based composite
bioscaffolds showed relatively high T dmax of 270 – 280°C for

microstructure I. The microstructure I could be regarded as
cross-linked ALG molecules with Ca ions.
2+
New microstructures IV were formed and observed
as shown in DTG results of Figure 9D and E when an
increased amount of SFDDS was buried into alginate-
based composite bioscaffolds with 0.5 wt% CaCl . T dmax of
Figure 8. TGA and DTG results of alginate-based composite bioscaffolds: 2
(A) ADDS1T1, (B) ADDS1T2, (C) ADDS1T3, (D) ADDS1T4, and (E) cross-linked composite bioscaffolds, which was relatively
ADDS1T5. higher than 400°C, was observed, as shown in Figure 9C-E.

Volume 9 Issue 1 (2023) 42 http://doi.org/10.18063/ijb.v9i1.625