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Fayyazbakhsh, et al.
body movement with no pain or trauma in the wound chronic wounds with moderate to high exudation rather
site. than burn wound healing, which requires continuous
Hydrogels are an essential class of polymers hydration instead of moisture absorption. To meet the
for dermal/epidermal regeneration (ER) due to their specific needs of burn wound that vary with wound
ability to donate and absorb water based on the wound size, depth, and patient condition, 3D printing has the
condition. DTE mainly involves biodegradable hydrogels capability to fabricate personalized wound dressings [29] .
to encourage wound healing process within a moist The first attempt at developing 3D-printed dressings
environment [9,15] . Since 1977 when hydrogels were for burn wound treatment was published in 2021
introduced as wound dressings for the 1 time , they by Teoh et al. [29] . They used extrusion-based 3D
st
[16]
have been developed from single-component hydrogels printing to develop personalized wound dressings with
to complex compounds reinforced with nanoparticles, chitosan methacrylate loaded with different drugs and
peptides, and growth factors . Gelatin and alginate have antimicrobial agents for burn wound treatment. To
[17]
been investigated for wound healing in various forms the best of our knowledge, no previous research has
such as amorphous gels and films, mostly for wet and investigated 3D-printed dressings with different ratios
exuding wounds. Gelatin accelerates the inflammatory of gelatin and alginate blend for burn wound treatment,
response and healing process by regulating macrophages and the effect of gelatin: alginate ratio on printing
and providing arginine−glycine−aspartic acid (RGD) outcome and functionality of the 3D-printed dressings
sequences, and sodium alginate facilitates autolytic has remained unclear. Furthermore, there is a need for
debridement [18-20] . Finding the adequate alginate-gelatin deeper evaluation of therapeutic efficacy of the 3D
ratio in a hydrogel blend for wound dressing is critical to printing technology considering the known benefits of
the success of wound healing, since gelatin and alginate non-printed gelatin-alginate hydrogels in burn wound
have different mechanical, gelation, and biological treatment. The current research investigates the effect of
properties due to the structural difference. To the best of gelatin: alginate ratio on printing outcome and hydration
our knowledge, despite the wealth of literature on the use activity, as a specific need of burn wound treatment.
of gelatin-alginate compounds as wound dressings, only We highlight in the present paper the therapeutic effect
one study evaluated different ratios of gelatin: alginate for of 3D printing technology by comparing 3D-printed
burn wound healing . In 2020, Afjoul et al. examined dressings with non-printed hydrogel dressing of the
[21]
[21]
freeze-gelled highly porous gelatin-alginate dressings same composition.
with a 3% w/v concentration for second-degree burn In this study, 3D-printed acellular dressings with
wound treatment, which exhibited fast degradation and different ratios of gelatin and alginate were fabricated
high swelling ratio not indicated for burn wound healing. and characterized for further enhancement of burn
The application of gelatin and alginate hydrogels for burn wound care products. To tune the gelatin: alginate ratio
wound dressing is limited by fast degradation, short- at a favorable level for 3D printing, the rheological
term fixity, and traumatic adherence to the wound bed. behavior and shear thinning behavior of the hydrogels
These shortcomings can be addressed by increasing the were measured. Mechanical properties, degradation
concentration of gelatin-alginate in the hydrogel blend and rate, and hydration activity were measured to relate
using different fabrication methods such as 3D printing the functionality of the 3D-printed dressings with
to develop hydrogel dressings with controlled pore size, gelatin: alginate ratio. MTT and Live/Dead assays were
tunable water absorption/donation, and improved fixity used to evaluate the biocompatibility of the dressings
on the wound. using human dermal fibroblasts (HDF). An in vivo wound
Over the last decade, skin bioprinting as an healing study was conducted using the most effective
extension of 3D printing has been widely investigated dressing in terms of stiffness, hydration activity, and
to develop various tissue engineering constructs for cell viability on deep PTB wound in a rat model. The
artificial skin, synthetic grafts, and wound dressings. Skin wound healing activity of the most effective 3D-printed
3D bioprinting allows for the reproducible fabrication dressing was compared with non-printed hydrogels
of various bioinks and cells with precise control over of the same formulation and petrolatum gauze, which
the structure, geometry, mechanical properties, and served as the control group.
functionality of the graft or dressing [22-25] . Researchers
mainly focused on developing 3D bioprinted skin 2. Materials and methods
grafts using various materials and cells [26-28] , rather than 2.1. Materials
developing 3D-printed wound dressings specifically
for burn wounds [29] . The majority of prior research on Gelatin type B (from porcine skin), sodium alginate,
3D-printed wound dressings has focused on developing calcium chloride anhydrous, Dulbecco’s Modified
absorbent dressings for wet/exuding wounds and Eagles Medium (DMEM), fetal bovine serum (FBS), 1%

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