Engineering Ligament Scaffolds Based on PLA/Graphite Nanoplatelet Composites by 3D Printing or Braiding

Abstract

The development of scaffolds for tissue-engineered growth of the anterior cruciate ligament (ACL) is a promising approach to overcome the limitations of current solutions. This work proposes novel biodegradable and biocompatible scaffolds matching the mechanical characteristics of the native human ligament. Poly(L-lactic acid) (PLA) scaffolds reinforced with graphite nano-platelets (PLA+EG) as received, chemically functionalized (PLA+f-EG), or functionalized and decorated with silver nanoparticles [PLA+((f-EG)+Ag)], were fabricated by conventional braiding and using 3D-printing technology. The dimensions of both braided and 3D-printed scaffolds were finely controlled. The results showed that the scaffolds exhibited high porosity (>60%), pore interconnectivity, and pore size suitable for ligament tissue ingrowth, with no relevant differences between PLA and composite scaffolds. The wet state dynamic mechanical analysis at 37 °C revealed an increase in the storage modulus of the composite constructs, compared to neat PLA scaffolds. Either braided or 3D-printed scaffolds presented storage modulus values similar to those found in soft tissues. The tailorable design of the braided structures, as well as the reproducibility, the high speed, and the simplicity of 3D-printing allowed to obtain two different scaffolds suitable for ligament tissue engineering.

Biocompatible 3D-Printed Tendon/Ligament Scaffolds Based on Polylactic Acid/Graphite Nanoplatelet Composites

“…Composites of PLA and low concentrations of EG/few-layer graphene, produced by melt mixing, were reported to exhibit tensile properties that could be adequate for tendon and ligament regeneration applications, without significantly impairing the ductility [ 52 ]. Similar conclusions were obtained in our preliminary work [ 53 ] performed on 3D-printed composite scaffolds based on a non-medical-grade PLA reinforced with [f-EG)+Ag]. The resulting stress–strain curves of compression tests as a function of the filler content illustrated that the reinforcement did not significantly affect the ductility, even with a filler content of 2 wt.% [ 53 ].…”

“…Similar conclusions were obtained in our preliminary work [53] performed on 3D-printed composite scaffolds based on a non-medical-grade PLA reinforced with [f-EG)+Ag]. The resulting stress-strain curves of compression tests as a function of the filler content illustrated that the reinforcement did not significantly affect the ductility, even with a filler content of 2 wt.% [53]. However, ligaments experience dynamic loads during normal locomotion, and their response was influenced by their viscoelastic properties.…”

Engineered Highly Porous Polyvinyl Alcohol Hydrogels with Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Graphene Nanosheets for Musculoskeletal Tissue Engineering: Morphology, Water Sorption, Thermal, Mechanical, Electrical Properties, and Biocompatibility

“…The measurement of mechanical properties by dynamical mechanical analysis is a first approach to evaluate the applications of engineered scaffolds [48][49][50]. The complex modulus, storage modulus (E ), and loss modulus (E ), obtained in a wet environment (immersion bath) at 37 • C to simulate physiological conditions, are shown in Figure 8.…”