Poly(Lactic Acid)/Graphite Nanoplatelet Nanocomposite Filaments for Ligament Scaffolds

Abstract

The anterior cruciate ligament (ACL) is one of the most prone to injury in the human body. Due to its insufficient vascularization and low regenerative capacity, surgery is often required when it is ruptured. Most of the current tissue engineering (TE) strategies are based on scaffolds produced with fibers due to the natural ligament’s fibrous structure. In the present work, composite filaments based on poly(L-lactic acid) (PLA) reinforced with graphite nanoplatelets (PLA+EG) as received, chemically functionalized (PLA+f-EG), or functionalized and decorated with silver nanoparticles [PLA+((f-EG)+Ag)] were produced by melt mixing, ensuring good filler dispersion. These filaments were produced with diameters of 0.25 mm and 1.75 mm for textile-engineered and 3D-printed ligament scaffolds, respectively. The resulting composite filaments are thermally stable, and the incorporation of graphite increases the stiffness of the composites and decreases the electrical resistivity, as compared to PLA. None of the filaments suffered significant degradation after 27 days. The composite filaments were processed into 3D scaffolds with finely controlled dimensions and porosity by textile-engineered and additive fabrication techniques, demonstrating their potential for ligament TE applications.

A Review of Polymer-Based Materials for Fused Filament Fabrication (FFF): Focus on Sustainability and Recycled Materials

“…Metals and ceramics are also used in the form of nanoparticles, to improve the mechanical and thermal properties of polymeric composites: these materials are called nanocomposites and exhibit excellent thermal, mechanical and transport properties [ 15 , 16 , 17 , 81 , 84 , 85 , 86 ]. Specifically, these nanoparticles include exfoliated clay and exfoliated graphite, carbon nanotubes, carbon nanofibers, nanocrystalline metals and a range of other nano-sized inorganic fillers [ 41 , 43 , 84 ].…”

“…The addition of highly conductive fillers, such as graphene oxide, graphene nanoplatelets [ 66 ], graphite nanopatterns (GNP), boron nitride (BN), carbon nanotubes (CNT), MWCNT, metals and others allow the limits due to the low thermal conductivity (TC) of the polymer matrix (generally 0.1–0.5 W m −1 K −1 ) to be overcome [ 88 ]. Silva et al (2021) have developed tissue-engineered composite filaments of PLA reinforced with graphite nanoparticles (PLA + EG), chemically functionalized (PLA + f-EG), or functionalized and decorated with silver nanoparticles (PLA + ((f-EG) + Ag)) [ 86 ]. The composite filaments produced are thermally stable.…”

“…The composite filaments produced are thermally stable. Furthermore, the incorporation of graphite increases the stiffness of the composites and decreases the electrical resistivity, compared to the electrical resistivity of PLA [ 86 ]. Nanoinclusions have also been used to improve antibacterial and biocompatible performance in tissue engineering [ 84 , 86 ].…”

“…Furthermore, the incorporation of graphite increases the stiffness of the composites and decreases the electrical resistivity, compared to the electrical resistivity of PLA [ 86 ]. Nanoinclusions have also been used to improve antibacterial and biocompatible performance in tissue engineering [ 84 , 86 ]. Bayraktar et al (2019) developed 3D printable antibacterial composites by adding silver nanowires (AgNW) in small percentages to the PLA matrix [ 78 ].…”

Feasibility study of oxidized naringin as a novel crosslinking agent for crosslinking decellularized porcine Achilles tendon and its potential application for anterior cruciate ligament repair

“…31 In short, the Nar (1 g) was added in 200 ml distilled water. After heating to dissolve, 0.4 g sodium periodate (equimolar reaction, slight excess of sodium periodate) was added to the solution and then stirred with 600 r/min in dark to predetermined time (6,12,24,48, and 72 h). The reaction was neutralized by the addition of 10 ml ethylene glycol to reduce the excess periodate.…”