Anisotropic solid-state PLA foaming templated by crystal phase pre-oriented with 3D printing: cell supporting...

Creating artificial structures that mimic the complex architecture of natural bone remains a challenge. While 3D printing offers shape control, it lacks the resolution needed for microscale features. Current high-resolution printing methods cannot scale to larger objects. Bone's Haversian canals and canaliculi provide mechanical strength and nutrient transport, but replicating these features is difficult. Prior research has shown that D printing can produce macroscale objects but not with submicron precision. This gap motivated the search for a method that can create aligned microporous canals at multiple scales. Existing techniques fail to combine high resolution with large-scale fabrication. No prior work had resolved how to align micropores in a polymer using phase-controlled crystallization. This uncertainty drove the development of a new approach using polylactic acid (PLA) and anisotropic foaming.

The study aimed to develop a method for creating aligned microporous canals in polylactic acid (PLA) that mimic the structure of bone canaliculi. The goal was to overcome the limitations of traditional 3D printing by using anisotropic foaming and crystalline pre-orientation. The researchers wanted to achieve submicron to macro-scale control over canal structure. They also sought to evaluate mechanical and transport properties of the resulting material. The motivation was to enable cell-supporting scaffolds with directional nutrient transport. The method needed to be scalable while maintaining fine canal dimensions. The study focused on combining 3D printing with controlled crystallization and foaming. The researchers aimed to demonstrate that this approach could produce hierarchical, aligned structures.

The method used polylactic acid (PLA) as the base material. First, the PLA was pre-oriented using 3D printing to establish directional alignment. Next, the material was orientedly crystallized in carbon dioxide (CO₂) to control crystal phase. After crystallization, the sample was foamed to create microporous structures. The foaming process was followed by cryo-shrinking to refine canal dimensions. The resulting canals were analyzed using wide-angle X-ray scattering (WAXS) to assess crystallinity. Fourier-transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) were used for additional characterization. Mechanical properties were tested to evaluate structural strength. Biocompatibility was assessed to determine suitability for cell support. Capillary transport was measured to confirm directional flow properties.

The method successfully produced hierarchically aligned microporous canals in PLA. Canal dimensions reached submicron scales, surpassing typical 3D printing resolutions. WAXS confirmed the presence of oriented crystalline structures. FTIR and DSC analyses supported the phase-controlled crystallization process. Mechanical testing showed the material retained sufficient strength for structural applications. Biocompatibility tests indicated the material was suitable for cell support. Directional capillary transport was observed, mimicking natural bone canaliculi. The method enabled control over canal alignment and size across multiple scales. These results suggest potential for advanced scaffolds with built-in nutrient delivery.

The study demonstrated a method for creating aligned microporous canals in PLA using anisotropic foaming and crystalline pre-orientation. The resulting structures mimic the hierarchical organization of bone canaliculi. The method achieved submicron canal dimensions while maintaining macroscale control. The material exhibited mechanical strength and biocompatibility suitable for cell support. Directional capillary transport was confirmed, suggesting potential for nutrient delivery. The approach offers a scalable alternative to traditional 3D printing techniques. The findings support the use of this method for advanced cell-supporting scaffolds. The authors suggest further exploration of the material's functional properties.