Page 144 - IJB-9-6

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

2.6. Swelling capacity and biodegradation rate where W is the initial weight, W is the weight after
0
H
measurement heating at 250°C, and W is the weight after 24 h placing
24
The swelling capacity and degradation rate of the on dry surfaces.
3D-printed dressings were measured by measuring the The water release profile was calculated and plotted
gravimetric changes of the samples after immersing in against time (up to 10 days). To determine the water release
PBS. The samples were weighed, immersed in PBS, and kinetics, the release profile was analyzed using different
kept at 32°C to reach equilibrium swelling and subsequent kinetic models, including zero-order, first-order, Higuchi,
degradation. The weight changes in determined time Korsmeyer–Peppas, and Hixon–Crowell for each dressing
intervals were recorded for up to 7 days as the dressings formulation .
[64]
are intended to stay on burn wounds for up to 7 days (n
= 5). The dressing’s swelling capacity and degradation rate 2.8. MTT assay
were calculated using the following equations: The MTT assay was used to study the effect of BBG on
the viability and proliferation of human dermal primary
(I) fibroblast cells (ATCC, Virginia, USA) at passages 3
and 4. 3D-printed dressings were weighed and exposed
to ultraviolet light (345 nm) for 15 min per side, then
(II) immersed in DMEM with no further treatment. The sample
extracts were collected and filtered after 1, 3, and 7 days
where W is the initial dry weight, W max is the maximum of immersion (five replications). The sample extracts were
Dry
weight of the scaffolds after immersion, and W day10 is the used to indirectly evaluate the cell viability in accordance
weight after 10 days of immersion in PBS. with the ISO-10993 standard. The DMEM culture media
with no further treatment was considered the control
2.7. Hydration activity and water release sample. Cells were cultured in DMEM containing 10% FBS
kinetics measurement and 1% pen/strep until they reached 80%–90% confluence.
To measure the effect of BBG on the water release rate, Cells were seeded in 96-well plates at a density of 10 cells/
4
the hydration activity was measured, as described in our well with 100 μL of DMEM containing 10% FBS and 1%
previous work . Briefly, the total amount of water in each pen/strep. The plates were incubated at 37°C with 5% CO .
[16]
2
sample was measured using thermogravimetric analysis After 24 h, the initial culture media were discarded and
(TGA) on 250°C for 10 min (SDT Q600 V20.9 Build 20, replaced by 90 μL sample extracts with 10% FBS and 1%
Universal V4.5A TA Instruments, Minnesota, USA). The pen/strep. Following 24 h of treatment, 100 μL of 0.5 M
weight change was considered the total water content MTT solution was added to each well and incubated for 4
(n = 5) . h. Formazan crystals were solubilized using isopropanol,
[60]
To predict the hydration activity of the samples on and after 30 min, the absorbance was measured at 545
burn wounds, the water release rate from each sample nm using an ELISA reader (Stat Fax 2100, Awareness
was measured using an ethylcellulose super absorbent Technology Inc., Florida, USA).
foam (Shield Line LLC, New Jersey, USA), as a model of 2.9. Animal test
the dehydrated burn wound. After placing the 3D-printed
dressings on the foam surface, the gravimetric changes 2.9.1. In vivo burn wound model
were measured after 24 h at 32°C, as the temperature of All in vivo experiments were approved by the Missouri S&T
the burned area is often lower than the normal body Institutional Animal Care and Use Committee (IACUC)
temperature . The 24-h hydration is a key factor in burn (Reference No. 177-20). The ability of the 3D-printed
[61]
wound treatment outcome, as the systemic capillary leak, wound dressings for the treatment of second-degree burn
intravascular fluid loss, and significant fluid shifts mostly wound was evaluated by creating a circular burn wound
occur within the first 24 h, peaking at around 6–8 h after in the dorsal area of Sprague Dawley rats using a hot
injury [62,63] . The total water content and water release rate aluminum bar. Thirty-six Sprague Dawley rats (Charles
were calculated using the following equations: River, Missouri, USA) were divided into six groups with
six animals per group:
(III)
(i) Control: Wounds covered with petrolatum gauze as
the current standard of care
(IV) (ii) BBG powder: Wounds covered with BBG powder

Volume 9 Issue 6 (2023) 136 https://doi.org/10.36922/ijb.0118