Fused Deposition Modeling and Characterization of Heat Shape Memory Poly(lactic) Acid-Based Porous Vascular Scaffold

Abstract

Shape memory polymers have received widespread attention from researchers because of their low density, shape variety, responsiveness to the environment, and transparency. This study deals with heat-shape memory polymers (SMPs) based on polylactic acid (PLA) for designing and fabricating a novel porous vascular scaffold to treat vascular restenosis. The solid isotropic material penalization method (SIMP) was applied to optimize the vascular scaffolds. Based on the torsional torque loading of Hyperworks Optistruct and the boundary conditions, the topological optimization model of a vascular scaffold unit was established. Forward and reverse hybrid modeling technology was applied to complete the final stent structure’s assembly. The glass transition temperature for the present SMPs is 42.15 °C. With the increase in temperature, the ultimate tensile strength of the SMPs is reduced from 29.5 MPa to 11.6 MPa. The maximum modulus at room temperature was around 34 MPa. Stress relaxation curves show that the material classification is a “thermoset” polymer. The superb mechanical properties, the transition temperature of the SMPs, and the recovery ratio made it a feasible candidate for a vascular scaffold. A circular tube based on the shape memory polymers was presented as an example for analyzing the recovery ratio in an unfolding state. A higher recovery ratio was obtained at a temperature of 65℃ with a tube thickness of 2 mm. Finally, the proposed porous vascular scaffold was successfully fabricated, assessed, and compared with the original and previously developed vascular scaffolds. The proposed scaffold structure regains its initial shape with a recovery ratio of 98% (recovery temperature of 47 °C) in 16 s. The tensile strength, Young’s modulus, and bending strength of the proposed scaffold were 29.5 MPa, 695.4 MPa, and 6.02 MPa, respectively. The results showed that the proposed scaffold could be regarded as a potential candidate for a vascular implantation.

Sustainable Robots 4D Printing

“…Reproduced under the term of CC‐BY license. [ 123 ] Copyright 2023, The Authors, published by MDPI. e) PLA‐based gripper made of the bioinspired pattern.…”

“…The researchers used 4D printing to prepare stents with different unit cells and investigated the effect of the helical angle on the shrinkage ratios of the stents. Zhang et al [ 123 ] reported the use of SMPs based on PLA for designing and fabricating a novel porous vascular scaffold to treat vascular restenosis employing the FFF method (Figure 5d). The SMPs were characterized for their thermal, mechanical, and shape memory properties, and it was found that they could be perfectly adaptable in fabricating the vascular scaffold for vascular implantation.…”

“…The SMPs were characterized for their thermal, mechanical, and shape memory properties, and it was found that they could be perfectly adaptable in fabricating the vascular scaffold for vascular implantation. [ 123 ] The proposed scaffold structure regains its initial shape with a recovery ratio of 98% (recovery temperature of 47 °C) in 16 s. Zhao et al [ 82 ] 4D printed a bioinspired tracheal scaffold using PLA and Fe 3 O 4 nanoparticles employing the FFF method. The fabricated scaffold changed shape when exposed to a magnetic field.…”

“…No-tably, from a material point of view, PLA has been employed the most in the fabrication of biodegradable soft actuators. Many authors have reported the applicability of this material as a SMP in thermal, [61,71,73,81,82,116,119,120,[123][124][125][126][127][128]132,133,197] electrothermal, [109] electrochemical, [135] magnetic, [69,75,78,82,197] and electrohydraulicbased [102,121] actuating soft systems.…”

“…Regarding their applicability, biodegradable 3D/4D printed soft actuators are utilized in many fields, such as agriculture, [ 60 ] biomedicine, [ 61–93 ] micro positioning, [ 67,79,94–97 ] smart surgical instruments, [ 64,98–101 ] soft rehabilitation devices, [ 98,102,103 ] drug delivery microswimmers, [ 64,67,68,70,72,73,77,84,85,88,94,34,104–108 ] sustainable electronics devices, [ 109–111 ] soft smart fabrics, [ 64 ] muscle tissue membranes, [ 65,76,89,94,96,112,113 ] in‐vivo robotics, [ 67,74,83,86,89–91,93,99–101 ] wearable devices, [ 95,103,111,114–118 ] soft smart prosthetics, [ 114 ] bionic devices, [ 69,72,73,114 ] aeronautics, [ 119,120 ] health monitoring equipment, [ 111,118 ] edible robots, [ 121 ] biomimetic scaffolds, [ 30,62,76,97,115,122,123 ] environmental monitoring equipment, […”