Template-oriented synthesis of hydroxyapatite nanoplates for 3D bone printing

Current methods for artificial bone tissue fabrication rely on the precise design of hydroxyapatite (HA) nanostructures. While HA is widely used for its biocompatibility, the architecture of HA nanoparticles significantly influences the final product's mechanical and biochemical properties. Prior research has shown that HA's crystallinity and morphology affect cell interactions and mechanical strength. However, achieving controlled HA nanostructures remains a challenge. Conventional synthesis methods often lack the precision needed for 3D printing applications. This gap motivated the development of a novel hard-template approach. No prior work had resolved the exact role of graphitic nitride in HA nanoplate formation. The need for scalable, high-quality HA structures for 3D printing remains unmet. Understanding the relationship between HA morphology and composite performance is essential. This study addresses the need for a reproducible method to produce HA nanoplates.

This study aimed to develop a reliable method for synthesizing hydroxyapatite (HA) nanoplates suitable for 3D bone printing applications. The goal was to produce single-crystal HA nanoplates with controlled dimensions using a hard-template approach. The specific problem addressed was the lack of scalable methods to fabricate HA structures with consistent morphology. The motivation stemmed from the need for improved mechanical and biological performance in artificial bone composites. The study focused on using graphitic nitride (g-C₃N₄) as a template to guide HA nanoplate formation. The objective was to optimize the HA structure for integration with polylactic acid (PLA) in 3D printable composites. The study also aimed to evaluate the biological compatibility of the resulting materials. The ultimate goal was to provide a reproducible and scalable synthesis method for 3D bone printing.

The synthesis of hydroxyapatite (HA) nanoplates involved a hard-template approach using graphitic nitride (g-C₃N₄). The process began with the preparation of an HA sol-gel under hydrothermal conditions. The g-C₃N₄ template was then removed through calcination at elevated temperatures. This step led to the formation of HA nanoplates with a thickness of approximately 100 nm. The lateral dimensions of the nanoplates reached the micrometre scale. Characterization techniques included X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). Theoretical predictions based on Wulff's method were used to model the nanoplate morphology. The HA nanoplates were then combined with polylactic acid (PLA) at varying weight ratios to form composites.

The synthesis produced HA nanoplates with a thickness of approximately 100 nm and lateral dimensions in the micrometre range. XRD confirmed the crystallinity of the HA nanoplates. TEM and HRTEM imaging revealed the nanoplate morphology and confirmed single-crystal formation. The theoretical predictions based on Wulff's method aligned with the experimental observations. The HA nanoplates were successfully combined with polylactic acid (PLA) in various ratios. The composite with the highest mechanical robustness was identified through mechanical testing. The (110) facet of HA was found to interact strongly with PLA, contributing to the composite's strength. Biological experiments showed that the composite exhibited excellent viability in vitro.

The study demonstrated a successful method for synthesizing hydroxyapatite (HA) nanoplates using a hard-template approach. The resulting nanoplates had a thickness of approximately 100 nm and were single-crystal structures. The use of graphitic nitride (g-C₃N₄) as a template allowed for precise control over HA morphology. The HA nanoplates were integrated into polylactic acid (PLA) composites for 3D printing applications. The (110) facet of HA was found to interact strongly with PLA, enhancing the composite's mechanical properties. Mechanical testing identified an optimal composite ratio for further biological evaluation. In vitro experiments confirmed the composite's biocompatibility and viability. The study provides a reproducible method for producing HA nanoplates suitable for 3D bone printing.