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International Journal of Bioprinting Design and property of PLPG/PDLA scaffold

1. Introduction p-dioxanone (PDO) and GA reduces the crystallization
capacity of PLPG. Previous studies have indicated
Bone tissue defects caused by trauma, infection, and that nucleating agents can significantly enhance the
congenital diseases significantly impact individuals’ crystallization capacity of PLLA copolymers. 14,15
1-3
health. Currently, bone tissue engineering is regarded Stereocomplex poly(lactic acid) (SC-PLA), known for
as one of the most promising methods for repairing its good biocompatibility, can be formed in situ by the
bone tissue defects. Bone scaffolds can be achieved by
adjusting the shape, hole size, and density of the scaffold, interaction of PLLA and poly(D-lactic acid) (PDLA)
16-18
as well as providing cells with the 3D space needed for segments through hydrogen bonding. The melting
survival like natural bone. This allows the cells to absorb temperature (776) of SC-PLA is approximately 220°C,
19,20
sufficient nutrients, exchange gases, and eliminate waste, considerably higher than that of PLLA. Thus, when the
enabling them to grow on the bone scaffolds according temperature reaches the T of PLLA during processing,
m
to the prefabricated form. This approach combines cells, SC-PLA remains in a granular form within the system.
biological materials, or scaffolds to create biological Additionally, SC-PLA crystals can be generated by
constructs, implants, or tissues that restore the structure introducing a small amount of PDLA, thereby increasing
and function of damaged tissues in vivo. Generally, bone the overall crystallization rate of PLLA. SC-PLA has
4,5
scaffolds need to have high mechanical properties and been widely utilized as a nucleating agent to enhance
provide stable mechanical support for bone defects, which the crystallinity of PLLA copolymers due to its high
21-23
significantly prevent fractures or joint instability caused by growth rate.
bone defects. Besides, in order to form a good interface Currently, 3D printing technology has emerged as a
combination with the tissues around the defect site, the crucial method for manufacturing porous scaffolds with
scaffold also needs to have good biocompatibility and high surface areas and mechanical performance. 24,25 This
reduce inflammation and rejection. In addition, the stent technology allows for alterations in surface roughness
can be gradually degraded and absorbed in the human and fiber arrangement, particularly in the creation of
body, avoiding the pain and risk associated with a second interconnected pore structures, enabling the production
operation to remove it. Meanwhile, the shape and structure of complex 3D architectures. When an ideal 3D
26
of the scaffolds could be customized to the specific needs scaffold is implanted at bone defect sites, it regulates cell
of the patients, which helps to personalize treatment plans migration, adhesion, and proliferation by mimicking the
and improve treatment outcomes and patient satisfaction. micro-nano structure of bone tissue, thus promoting
Various synthetic polymers have been extensively used new bone regeneration. 27,28 In our previous published
in the fabrication of bone tissue engineering scaffolds article, we studied the performances of PLPG/PDLA
due to their favorable processing, mechanical properties, blends, and the results indicate that SC-PLA crystals
biocompatibility, and biodegradability. Among these, could be in situ generated by the H bond between PLPG
6-8
poly(L-lactic acid) (PLLA), a thermoplastic elastomer, and PDLA. Therefore, the primary aim of this study is
29
possesses good processability, mechanical properties, and to investigate the influence of in situ SC-PLA formation
degradation characteristics, and has been approved by on the properties of PLPG/PDLA scaffolds resulting from
the United States Food and Drug Administration (FDA) the introduction of PDLA into the PLPG matrix. PLPG/
for clinical applications, such as vascular prostheses, PDLA blends were prepared via solution blending and
peripheral nerve repair, and urethral reconstruction. subsequently processed into scaffolds using 3D printing
9,10
However, PLLA has notable shortcomings, including technology. The selected processing temperature of
poor toughness and a slow degradation rate, which 170°C ensures that PLPG is fully melted while the in situ-
impede its medical applications. 11,12 In our previous formed SC-PLA remains in granular form, effectively
study, PLLA-ran-PDO-ran-GA (PLPG) copolymers enhancing the crystallization capacity of the PLLA chain
were synthesized using poly(p-dioxanone) (PPDO) segments in the PLPG copolymers. For clarity, the PLPG/
for its flexibility and mechanical strength, along with PDLA scaffolds are designated as PLPG/PDLA-3, PLPG/
glycolic acid (GA) for its reactivity, through ring-opening PDLA-5, PLPG/PDLA-7, and PLPG/PDLA-10 based on
polymerization. Subsequently, PLPG scaffolds were the amount of PDLA used. For example, PLPG/PDLA-3
fabricated using 3D printing technology, demonstrating represents a mass ratio of 97:3 between PLPG and PDLA.
good mechanical performance, degradation properties, The surface morphology, degradation and mechanical
and biocompatibility. 13 properties, and in vitro biocompatibility of the PLPG/
Although PLPG copolymers exhibit excellent PDLA scaffolds were studied to assess their potential
degradation and toughness, the introduction of applications in bone tissue regeneration.

Volume 10 Issue 6 (2024) 533 doi: 10.36922/ijb.4645