Page 150 - IJB-9-6

International Journal of Bioprinting 3D printed bioactive dressings for burn wound treatment

Table 2. Release kinetic models and parameters for water release from 3D-printed dressings
Release kinetics model Hydrogel Hydrogel–BBG10 Hydrogel–BBG20
Zero-order R = 0.9494 R = 0.9183 R = 0.9815
2
2
2
2
2
2
First-order R = 0.9826 R = 0.9446 R = 0.9960
Korsmeyer–Peppas R = 0.7389 R = 0.7112 R = 0.6782
2
2
2
Higuchi a R = 0.9891 R = 0.9696 R = 0.9983
2
2
2
Hixon Crowell R = 0.5432 R = 0.5831 R = 0.7138
2
2
2
Drug release parameters
Burst release (%) 71.51 ± 1.59 53.07 ± 2.87 42.14 ± 0.2
Total release (%) 87.09 ± 1.73 71.77 ± 6.44 67.86 ± 3.2
Sustained release (%) 15.58 ± 3.27 18.69 ± 3.82 25.79 ± 3.07
Sustained release/burst 0.21 0.38 0.55
release
Release rate (mg/day) 1.73 2.07 2.85
a The water release kinetics in all samples demonstrate the highest coefficient of determination (R2 value) when fitted to the Higuchi model compared to
other models..
hydrogel dressings (without BBG) can be associated and granulation tissue formation in the 3D-printed
with the time-dependent denaturation of amino acid hydrogel and hydrogel–BBG20 dressings with the non-
sequences in gelatin and acidic degradation of alginate. printed hydrogels of the same formulation. The as-received
These results show that the biocompatibility of the BBG powder and commercial petrolatum gauze served as
samples is time-dependent and promoted by increasing control groups. Wound images on days 0, 7, 14, 21, and 28
the cumulative therapeutic ions released from BBG were analyzed to estimate the wound contraction/closure
while negatively affected by the timely decomposition of ranging from the initial deep partial-thickness burn of
the gelatin–alginate compound. The ion released from 20 mm diameter on day 0 to the total wound closure on
BBG shifts the pH to alkaline ranges, while the hydrogel day 28. Figures 8 and 9 present the changes in wound
degradation shifts the pH to acidic ranges. The improved appearance and area, i.e., wound closure, as a key factor
cell viability in hydrogel–BBG20 samples indicates that in wound assessment. All samples showed faster wound
the BBG content dominantly affects cell viability. In the closure compared to the control and BBG powder groups.
same line, the reduced cell viability in hydrogel–BBG10 Despite the excellent outcomes for chronic wounds, BBG
samples compared to hydrogel–BBG20 samples shows has no therapeutic effect on burn wounds, which is due to
that in this sample, the cell viability is mainly affected by the absence of aqueous media for therapeutic ion release
the adverse interactions between alkaline ions and acidic and transfer to the wound. These results also re-affirm
residues resulting from the decomposition of alginate. the positive effect of water release and hydrogel coverage
Hence, the hydrogel–BBG20 samples provide a favorable on burn wound healing. Among the hydrogel samples,
balance between the alkaline pH caused by ion released 3D-printed hydrogel–BBG20 showed the fastest wound
from BBG and the acidic degradation of alginate. On the closure and earliest re-epithelialization (P < 0.05, n = 6).
other hand, the neutralized pH can preserve the arginine- Both 3D-printed and non-printed dressings with BBG
glycine-aspartic acid (RGD) sequences for a longer time showed smooth wound margins compared to the plain
and enhance cell proliferation and growth .
[80]
hydrogel samples with uneven wound margins. In contrast,
3.6. Animal test the BBG powder group showed the formation of thick scab
To assess the effect of BBG on the wound-healing activity layer, i.e., dry and rough wound crust. The 3D-printed
of the 3D-printed dressings, we conducted an in vivo study samples with and without BBG showed significantly faster
using a rat model with a second-degree burn wound. We wound closure than the non-printed dressings of the
compared the wound closure time, re-epithelialization, same composition.

Volume 9 Issue 6 (2023) 142 https://doi.org/10.36922/ijb.0118