Medical grade 3D printable bioabsorbable PLDL/Mg and PLDL/Zn composites for biomedical applications

Medical grade PLDL, PLDL/Mg and PLDL/Zn filaments were manufactured by a dual extrusion method and used to prepare coupons and scaffolds with controlled porosity by fused filament fabrication. The mechanical properties, degradation mechanisms and biological performance were carefully analyzed. It was found that the presence of 4 vol.% of Mg and Zn particles did not substantially modify the mechanical properties but accelerated the degradation rate of PLDL. Moreover, the acidification of the pH due to degradation of the PLDL was reduced in the presence of metallic particles. Finally, cell adhesion and proliferation were excellent in the medical grade PLDL as well as in the polymer/metal composites. These results demonstrate the potential of bioabsorbable metal/polymer composites to tailor the mechanical properties, degradation rate and biocompatibility for specific clinical applications.

Mechanical properties, in vitro degradation and cytocompatibility of woven textiles manufactured from PLA/PCL commingled yarns

The mechanical, thermal, and biological performance of fabrics manufactured with hybrid PLA/PCL commingled yarns were studied. Commingled hybrid yarns take advantage of the higher elastic modulus of PLA and the higher ductility and toughness of PCL to produce yarns and fabrics with high strength and ductility that is transferred to the woven textiles. Furthermore, PLA and PCL exhibit different degradation rates and also allow to tailor this property. Degradation of the textiles was carried out in phosphate-buffered saline solution for up to 160 days at 37 °C and 50 °C (accelerated degradation). Neither the thermal nor the mechanical properties were altered by immersion at 37 °C during 80 days and a slight degradation was observed as a result of chain scission of the PLA fibres after 160 days. However, immersion at 50 °C led to a rapid reduction in strength after 40 days due to the hydrolysis of PLA, and the fabric was highly degraded after 160 days as a result of chain scission in PCL. Finally, while indirect tests did not predict optimal biocompatibility, the direct tests provided a different perspective of the cell interaction between the textile and pre-osteoblasts regarding cell attachment and cell morphology. These results show the potential of hybrid commingled yarns to manufacture textile scaffolds of biodegradable polymers with tailored mechanical properties and good ductility for connective tissue engineering (ligaments and tendons).

Processing and mechanical properties of novel biodegradable poly-lactic acid/Zn 3D printed scaffolds for application in tissue regeneration

The feasibility to manufacture scaffolds of poly-lactic acid reinforced with Zn particles by fused filament fabrication is demonstrated for the first time. Filaments of 2.85 mm in diameter of PLA reinforced with different weight fractions of μm-sized Zn - 1 wt.% Mg alloy particles (in the range 3.5 to 17.5 wt.%) were manufactured by a double extrusion method in which standard extrusion is followed by precision extrusion in a filament-maker machine. Filaments with constant diameter, negligible porosity and a homogeneous reinforcement distribution were obtained for Zn weight fractions of up to 10.5%. It was found that the presence of Zn particles led to limited changes in the physico-chemical properties of the PLA that did not affect the window temperature for 3D printing nor the melt flow index. Thus, porous scaffolds could be manufactured by fused filament fabrication at 190 °C with poly-lactic acid/Zn composites containing 3.5 and 7 wt.% of Zn and at 170 °C when the Zn content was 10.5 wt.% with excellent dimensional accuracy and mechanical properties.

Nanostructured medical sutures with antibacterial properties

Bacterial repellence in suture materials is a desirable property that can potentially improve the healing process by preventing infection. We describe a method for generating nanostructures at the surface of commercial sutures of different composition, and their potential for preventing biofilm formation. We show how bacteria attachment is altered in the presence of nanosized topographies and identify optimum designs for preventing it without compromising biocompatibility and applicability in terms of nanostructure robustness or tissue friction. These studies open new possibilities for flexible and cost-effective realization of topography-based antibacterial coatings for absorbable biomedical textiles.