Physicochemical Properties of 3D-Printed Polylactic Acid/Hydroxyapatite Scaffolds

Restoring damaged bone tissue remains a significant challenge in orthopedic surgery and tissue engineering. Traditional methods often lack the precision needed for patient-specific solutions. Prior research has shown that additive manufacturing techniques, such as fused deposition modeling (3D-FDM printing), offer a promising approach for creating customized scaffolds. However, the use of pre-fabricated filaments limits flexibility and control. This gap motivated the investigation of direct 3D printing methods. That uncertainty drove the need to explore alternative fabrication techniques. No prior work had resolved the integration of hydroxyapatite (HA) into polylactic acid (PLA) scaffolds without requiring a filament. This study addresses the lack of detailed physicochemical and mechanical data on such direct-printed composites. It also fills the need for a systematic evaluation of scaffold architecture and cell compatibility.

This study aimed to evaluate the feasibility of direct 3D printing of polylactic acid (PLA) and hydroxyapatite (HA) scaffolds without relying on pre-fabricated filaments. The specific problem addressed is the limited adaptability of traditional 3D printing methods in bone tissue engineering. The motivation stems from the need for patient-specific scaffolds with controlled architecture and enhanced bioavailability. The study sought to determine whether HA could be efficiently incorporated into PLA scaffolds using direct printing. It also aimed to assess the resulting physicochemical and mechanical properties. The researchers proposed that varying HA ratios and infill percentages would influence scaffold performance. This work provides a foundation for tailoring scaffold properties for clinical applications. It also explores the potential of 3D-FDM printing in orthopedic tissue regeneration.

The study employed a direct 3D printing approach using fused deposition modeling (3D-FDM) to fabricate polylactic acid (PLA) and hydroxyapatite (HA) scaffolds. A range of PLA/HA ratios and infill percentages were tested to assess their impact on scaffold properties. Physicochemical characterization included scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) to analyze surface morphology and elemental composition. Fourier-transform Raman spectroscopy (FT-Raman) was used to evaluate molecular interactions between PLA and HA. X-ray diffraction (XRD) confirmed the crystallinity and phase composition of the scaffolds. Micro-computed tomography (micro-CT) provided detailed structural analysis of pore size and distribution. Nanoindentation measured mechanical properties such as Young's modulus. These methods collectively enabled a comprehensive evaluation of scaffold architecture and performance.

The study confirmed the successful incorporation of up to 13 wt.% hydroxyapatite (HA) into polylactic acid (PLA) scaffolds using direct 3D printing. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) showed uniform HA distribution at the macro level across both longitudinal and cross-sectional views. At the micro level, HA particles exhibited an exponential distribution from the surface toward the interior of the biocomposite cord within the first 80 µm. This surface enrichment increased scaffold roughness and bioavailability. Pore sizes ranged from 250 to 850 µm, with porosity percentages between 24% and 76% of the total scaffold volume. Mechanical testing revealed a ~50% increase in Young's modulus with higher HA content compared to pure PLA scaffolds. In vitro evaluation demonstrated MG63 cell proliferation on the scaffolds after 21 days of incubation. These findings suggest a strong correlation between HA content and scaffold performance.

The authors propose that direct 3D printing of polylactic acid (PLA) and hydroxyapatite (HA) scaffolds is a viable method for bone tissue engineering. The study confirms HA incorporation up to 13 wt.% with uniform macro-level distribution. Surface enrichment of HA particles within the first 80 µm of the cord enhances bioavailability and roughness. Scaffold porosity ranged from 24% to 76%, with pore sizes between 250 and 850 µm. Mechanical properties improved with HA content, showing a ~50% increase in Young's modulus. In vitro tests indicated MG63 cell proliferation on the scaffolds after 21 days. These findings suggest that direct printing allows for controlled scaffold architecture and enhanced performance. The methodology provides a flexible platform for tailoring scaffolds to patient-specific needs. The results support the use of this approach in orthopedic tissue engineering applications.