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

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 3Dprinting
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 37ºC revealed 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.