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International Journal of Bioprinting Review of 4D-printed smart medical implants

Figure 8. Application of 4D-printed scaffolds in cardiovascular diseases. (A) Self-expanded stent for vascular stenosis. [111] Copyright 2021, Elsevier.
(B) The deforming procedures of the folded stent inserted into the branched blood vessels [104] . Copyright 2019, Jove publishing. (C) 4D-printed shape
memory occlusion for atrial septal defect (ASD). [112] Copyright 2019, Wiley-VCH. (D) A 4D-printed NIR light-sensitive cardiac patch with highly aligned
myofibers for the treatment of myocardial infarction (MI) [110] . Copyright 2021, American Chemical Society.

hydrogel printed by femtosecond laser direct writing at 6. Conclusion and perspectives
the microscale in another study. They designed a complex
microcage to capture and release microparticles due to Overall, 4D printing is a potential candidate technology
the different pore sizes in the expanded and contracted in producing dynamic and functional scaffolds for
states, showcasing its possibility in drug delivery (Figure medical implantation. It developed from 3D printing and
10B) [114] . Utilizing the change of polymer network pore has made great progress in generating time-dependent
size to release drugs dynamically as required is also an drivable constructs when exposed to specific stimuli
efficient method [157] . By empowering implants with the instead of traditional static structures. The 4D-printed
ability of drug delivery, post-implantation infections scaffolds based on structural deformation demonstrate
can be prevented by antibiotics, primary diseases of great advantages in minimally invasive surgery due
implantation sites can be treated by therapeutic drugs, to their small to large volume transformation under
and diseased tissues can be repaired by growth factors stimulation, thus reducing intraoperative risk and
or other functional components. With the assistance improving patient prognosis. Meanwhile, they can be
of 4D printing, the drug delivery system can achieve programmed to fit perfectly to tissue defects by self-
more effective drug administration that delivers drugs deforming after implanted. 4D printing has great
on demand. It is expected to combine bioscaffolds with advantages in producing implants and substitutes
tunable functional drug delivery by 4D printing design, with specific shapes. Tubular and curved implants
which can realize the combination of dynamic repair and can be easily achieved through self-rolling and self-
dynamic drug administration for promotion of further bending, which are hardly achievable by the traditional
rehabilitation. manufacturing process. The 4D-printed cellular

Volume 9 Issue 5 (2023) 329 https://doi.org/10.18063/ijb.764