Page 187 - IJB-9-3

International Journal of Bioprinting Chitin/gelatin/PVA scaffolds

Figure 2. (A) Shear sweep and (B) frequency sweep tests for 3DP inks at 30°C, 32°C, and 35°C. (C) Shear sweep and (D) frequency sweep tests for ES inks
at 25°C.

[56]
Table 2. Zero shear rate viscosity (µ ), infinite shear viscosity based materials . Mucin, a negatively charged highly
0
(µ∞), time constant (C), and rate constant (m) of Cross model glycosylated protein, can provide physical interactions
for 3DP and ES samples (hydrogen bonds or electrostatic forces) with other
polymers . Therefore, in contact with the gelatin present
[55]
Sample T µ 0 µ∞ C m R 2
(ºC) (Pa s) (Pa s) (s) in 3DP ink, noncovalent interactions can be formed
3DP 30 605.77 3.59 0.30 1.66 0.99 through –COOH, –NH , and –OH polar groups present
2
in both proteins . As a result, good mucoadhesion
[53]
32 400.25 2.29 0.34 1.61 0.99 performance was observed for 3DP inks. This behavior
35 287.65 0.45 0.27 0.86 0.99 is considered interesting for biomedical applications in
ES 25 3.29 0.61 0.18 0.82 0.99 order to address the necessity to stick to target surfaces
and induce cell proliferation .
[17]
the scaffold were 25°C and 32°C for ES and 3DP inks,
respectively. TPA was carried out to assess the mechanical properties
of the scaffold under compression forces. TPA is commonly
3.3. Mucoadhesion and textural properties of used to study food-related materials , although it is a
[57]
3DP inks good approximation to analyze other types of applications
Mucoadhesion is defined as a state in which two materials like hydrogels for scaffolds in biomedical applications [58,59] .
(mucin and natural or synthetic polymer) adhere to each TPA consists of two compression cycles with a recovery
other via interfacial forces for a certain period of time [53,54] . time between them, and it is typically represented as a
Mucoadhesive polymers interact with mucosal membranes curve of force vs time , as shown in Figure 4 for 3DP inks.
[60]
because of their hydrophilicity and through different Two peaks were observed on the positive side (marked as
functional organic groups. These interactions might be 2 and 5) and a third peak on the negative side, whose area
covalent or non-covalent [53,55] . In this work, mucoadhesion (marked in green) represents adhesiveness (1.27 ± 0.43 g·s).
tests were performed to assess the adhesion behavior of The first peak describes the required force for a given
3DP inks. As shown in Figure 3, the value of the maximum deformation and represents the material hardness (25.21
force to separate the 3DP ink from mucin was 7.47 N, ± 7.54 g). The ratio of the positive force area during the
and the adhesion work, calculated by integrating the area second compression to that during the first compression
under the curve, was 6.96 mJ, which was higher than (marked in red) is related to the cohesiveness (1.02 ± 0.04).
those found in the literature for mucoadhesive gelatin- This parameter is related to the deformation degree of the

Volume 9 Issue 3 (2023) 179 https://doi.org/10.18063/ijb.701