Page 180 - IJB-9-5

International Journal of Bioprinting Functional materials of 3D bioprinting for wound healing

oxidative stress, enhancing the effect of growth factors, and a variety of hemostatic mechanisms. In recent years,
improving the wound microenvironment. Therefore, some composite hemostatic materials have been developed to
researchers combined antioxidants with other materials improve hemostasis efficiency and reduce hemostasis time.
to treat wound healing . Tang et al. prepared a pGO- Recently, Zheng et al. developed a novel W-8HAP-2PVA
[56]
[55]
[87]
CS/SF scaffold composed of chitosan (CS) and silk fibroin hemostatic aerogel based on ultralong hydroxylapatite
(SF) combined with PDA-reduced GO (pGO) with good (HAP) nanowires that could release Ca to trigger the
2+
electroactivity and antioxidant properties. pGO endowed coagulation cascade and promote platelet adhesion. The
the pGO-CS/SF scaffold with multiple functions. Due to porous structure of this aerogel could aggregate platelets and
the presence of reducing catechol groups on pGO, the blood cells by rapidly absorbing water, further promoting
scaffolds could scavenge ROS to reduce cellular oxidation. thrombosis and accelerating hemostasis. In addition, this
Moreover, the pGO-CS/SF scaffolds had good electrical aerogel could accelerate the healing of diabetic mouse
conductivity, which could regulate cell behaviors. The full- wound healing model. These results demonstrated that
thickness skin repair model in rats showed that pGO-CS/ the W-8HAP-2PVA aerogel was an excellent hemostatic
SF scaffolds could accelerate tissue regeneration. Therefore, material for future clinical and emergency applications.
the results suggested that the pGO-CS/SF scaffold might be
a promising wound dressing. 3.6. Flexible materials
Flexible materials generally refer to polymer materials that
have certain flexibility, stretch, bend, twist, and deform
3.5. Hemostatics without losing performance . Common flexible materials
[88]
The first stage of the wound healing process is hemostasis, include silicone elastomers, polycaprolactone (PCL),
and effective hemostasis is very important for subsequent poly(lactide-glycolide) (PLGA), polydimethylsiloxane
wound healing [81-83] . Since the inherent hemostatic (PDMS), polyester (PET), polyimide (PI), polyethylene
mechanism cannot effectively control bleeding, the timely naphthalene glycol (PEN), and the flexible component
use of hemostatic materials can reduce morbidity and material PLA, which are commonly used in flexible
mortality [22,24] . Therefore, the development of materials electronics , soft robotics , and biomedical
[90]
[89]
with excellent hemostatic activity is of great interest engineering . The application of flexible materials in
[91]
for controlling hemostasis and preventing of blood loss biomedical engineering is usually to integrate various
in the early stage of emergency trauma. So far, various electronic components on flexible substrates to form
materials used as hemostatic agents can be classified into flexible circuit boards with high flexibility and elasticity
natural hemostatic materials (fibrin, gelatin, chitosan, and like skin.
sodium alginate), inorganic hemostatic materials (zeolite,
montmorillonite, and kaolin), and synthetic hemostatic In wound healing research, bioengineered materials
materials (cyanoacrylate, acrylic, and polylactic acid) [84,85] . with high mechanical properties are widely used, while
An ideal hemostatic material should be biodegradable, flexible products are relatively rare; however, the stiffness
biocompatible, and low-cost, as well as can achieve rapid of materials may have an impact on cell behavior [92,93] .
hemostasis within 2 min . Flexible materials can be inserted between polymer
[86]
molecular chains to weaken the stress between molecular
The hemostatic mechanism of hemostatic materials chains and increase their fluidity, thus giving wound
is usually divided into active and passive pathways. The healing materials similar softness to natural skin, which
active pathway is to initiate the blood coagulation process is conducive to rapid tissue repair. Gao et al. reported
[61]
by specifically initiating the coagulation cascade. For the preparation of flexible bilayer poly(lactide-glycolide)
example, chitin and chitosan can promote the aggregation (PLGA) skin scaffolds using a solvent exchange deposition
of red blood cells and rapidly form blood clots by model (SEDM) phase separation combined with a rapid
activating platelets . Kaolin can combine with plasma in situ formation system of electrospinning technology.
[58]
and activate coagulation factors of internal coagulation The addition of this flexible biodegradable polyester makes
cascade to promote hemostasis . The passive approach the scaffold flexible, which is conducive to cell growth, and
[59]
requires specific surface properties (antithrombotic, anti- effectively promotes wound healing in rats.
infective, and hemocompatibility) of hemostatic materials
to achieve hemostasis [24,57] . Resistant starch and cellulose 3.7. Antitumor materials
can quickly form a physical barrier through rapid water Antitumor materials are indispensable materials for
absorption and expansion, leading to blood aggregation suppressing residual or recurring cancer cells in patients
and coagulation . The development of composite with malignant tumors whose tissues are surgically
[60]
hemostatic materials can improve the hemostatic removed. It is divided into natural drugs (anthocyanin
efficiency and shorten the hemostatic time through and curcumin) and chemically synthesized drugs

Volume 9 Issue 5 (2023) 172 https://doi.org/10.18063/ijb.757