Page 438 - IJB-9-3

International Journal of Bioprinting Gelatin-PVA crosslinked genipin bioinks for skin tissue engineering

GE_GNP was 680.33 ± 177.4% and was significantly GPVA5_GNP showed superior free radical scavenging
higher than the GPVA3_GNP and GPVA5_GNP (619.61 property according to the DPPH results, clearing over 45% of
± 218.4% and 590.93 ± 164.7%). The swelling ratio for the free radicals, while the GPVA3_GNP and GE_GNP had a
GE_NC, GPVA3_NC, and GPVA5_NC was higher than scavenging ratio of 37.0 ± 3.6% and 27.7 ± 3.1%, respectively.
those for GNP hydrogels (1217.11 ± 317.7%, 879.23 ± Moreover, ABTS scavenging activity also demonstrated the
57.4%, and 861.61 ± 114.2%). However, the swelling rate same trend as the DPPH assay as shown in Figure 3G.
was slightly reduced in GPVA3_GNP and GPVA5_GNP
hydrogels, which may be due to the strengthening of the 3.4. Rheological properties of bioinks
pore structure of the hydrogel caused by GNP and PVA. Furthermore, the rheological analysis of hydrogels is
Next, the evaluation of the moisture level of the demonstrated in Figure 4. The viscoelastic features of the
hydrogels was determined through WVTR in Figure 3D. hydrogels were investigated to correlate the intermolecular
[31]
To achieve optimal wound site conditions, the hydrogels interaction forces with the hydrogel composition . The
should have an appropriate WVTR and an appropriate hydrogels were tested for rheological properties for both
water absorption capacity to regulate fluid balance. GE_ NC and GNP hydrogels. The average viscosity in Figure 4A
GNP has the highest WVTR (1096.90 ± 284.5 g/m /h), shows that the hydrogels have a similar trend in which
2
followed by GPVA3_GNP and GPVA5_GNP (1026.24 viscosity increases from 27 Pa.s to 19 Pa.s. Moreover, as
2
± 183.8 g/m /h and 778.51 ± 183.8 g/m /h, respectively). compared to the NC hydrogels, GPVA5_GNP, GPVA3_
2
In Figure 3E, the GNP hydrogels had >40% average GNP, and GE_GNP have higher viscosity (3.0 ± 0.06
crosslinking degree. The results clearly demonstrate that Pa.s, 0.2 ± 0.002 Pa.s, and 0.04 ± 0.01 Pa.s) compared to
hydrogels incorporated with higher concentrations of GPVA5_NC, GPVA3_NC, and GE_NC (0.7 ± 0.03 Pa.s,
PVA, GPVA5_GNP (53.53 ± 2.54%) had a significantly 0.06 ± 0.01 Pa.s, and 0.007 ± 0.009 Pa.s). This also proved
higher level of crosslinking degree compared to GE_GNP that the addition of GNP and PVA promote higher viscosity
only (46.57 ± 1.15%). to the hydrogels. Besides, based on the result in Figure 4B,
the viscosity begins to drop at low frequency. The changes
3.3. Antioxidant activity study of complex viscosity (η*) arise from the different solvent
The hydrogel-incorporated with GNP demonstrated superior varieties and solvent strengths. At 23°C, the complex
scavenging activity. GNP hydrogels had higher antioxidant viscosity of the crosslinked hydrogels began with GPVA5_
activity than NC hydrogels. The DPPH assay result showed GNP > GPVA3_GNP, and GE_GNP, (91384.2 ± 61415.71
in Figure 3F shows that the addition of GNP to the GPVA Pa.s, 11259.0 ± 17946.09 Pa.s and 15947.3 ± 16810.76 Pa.s)
hydrogels increased antioxidant capacity. The group of at 0.1 rad/s as compared to the non-crosslinked hydrogels.

A B

C
D

Figure 4. Rheological properties of the bioinks: (A) viscosity (η), (B) complex viscosity (η*), (C) storage modulus (G’), and (D) loss modulus (G’’).
*P < 0.05.

Volume 9 Issue 3 (2023) 430 https://doi.org/10.18063/ijb.677