Hybrid Composites of Phosphate Glass Fibre/Nano-Hydroxyapatite/Polylactide: Effects of Nano-Hydroxyapatite on Mechanical Properties and Degradation Behaviour

Abstract

Hydroxyapatite/polylactide (HA/PLA) composites have been intensively investigated for their potential as biodegradable fixation devices to heal bone fractures. However, most of these composites failed to achieve a bone-mimicking level of mechanical properties, which is an essential demand of the targeted application. In this study, the nano-hydroxyapatite/polylactide composites were used as the matrix and continuous phosphate glass fibres (PGF) served as the major reinforcement to obtain the nano-HA/PGF/PLA hybrid composites. While the PGF volume fraction remained constant (25%), the nano-HA content (in weight) varied from 0% to 20%. As nano-HA loading increased, the flexural modulus of the composites increased from 8.70 ± 0.35 GPa to 14.97 ± 1.30 GPa, and the flexural strengths were enhanced from 236.31 ± 10.83 MPa to 310.55 ± 22.88 MPa. However, it is found that the degradation rates are higher with more nano-HA loaded. Enhanced water absorption ability, as well as increased voids in the composites is possible reasons for the accelerated degradation of composites with higher nano-HA loading. The hybrid composites possess mechanical properties that are superior to most of the HA/PLA composites in previous research while maintaining the biodegradability. With a proper loading of nano-HA in composites of 10 weight percent, the composites are also found with improved mechanical properties without catastrophic degradation. The composites developed in this study have great potential as biodegradable bone fixation device with enhanced load-bearing ability as confirmed and superior bioactivity as anticipated.

Characterization of PLA/PCL/Green Mussel Shells Hydroxyapatite (HA) Biocomposites Prepared by Chemical Blending Methods

“…The structural characteristics of the biocomposites are another potential explanation for the degradation of the biocomposites, which accelerates with increasing HA content. The incorporation of HA and its agglomerates can also result in a larger absorption area for water infusion, thus, enabling faster biocomposite degradation [ 10 , 68 ]. The findings of this investigation are consistent with the study performed by Donate et al [ 69 ].…”

“…The preferred method of degradation is a slow, steady decline of mechanical qualities that permits the mechanical load to be gradually accepted by newly formed bones, therefore, providing the essential impetus for bone with the capacity to sustain load to be renewed. To prevent the failure of bone fixation, the fast loss of mechanical properties and implant failure (premature breakdown/deformation) must be prevented [ 68 ]. After implantation, the mechanical strength of PLA/PCL/HA decreased as a result of its rapid degradation [ 75 ].…”

“…After implantation, the mechanical strength of PLA/PCL/HA decreased as a result of its rapid degradation [ 75 ]. Due to partial bone fragment immobilization, a more rapid mechanical strength decline after implantation leads to insufficient recovery [ 68 , 75 , 76 ].…”

Additive-Manufactured Gyroid Scaffolds of Magnesium Oxide, Phosphate Glass Fiber and Polylactic Acid Composite for Bone Tissue Engineering

“…Conversely, it was reported that an increased HA loading in polylactic-co-glycolic acid (PLGA) led to even more pronounced pH reduction, due to the increased surface area of composites and a limited buffering ability of hydroxyapatite above the pH of 4.2 [ 26 , 29 ]. Previous work reported that the addition of HA into the PGF/PLA composite did not show any buffering effect, but led to a dramatically accelerated mechanical deterioration of composites instead [ 30 ].…”

Design, Manufacturing and Characterization of Biodegradable Bone Screw from PLA Prepared by Fused Deposition Modelling (FDM) 3D Printing Technique

“…The preferred mode of degradation is the slow, steady decline of mechanical properties that permits the mechanical stress to be gradually absorbed by newly formed bones, so providing the essential impetus for the regeneration of bone with load-bearing capability. In contrast, rapid loss of mechanical characteristics and implant failure (premature breakdown/deformation) should be avoided to prevent bone fixation failure [30]. The mechanical strength of biodegradable bone screws decreased after implantation due to their rapid rate of degradation [31].…”