Tailoring of processing parameters for sintering microsphere-based scaffolds with dense-phase carbon dioxide.

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Polymer Chemistry

Background:

• Microsphere-based scaffolds are crucial for tissue engineering, offering controlled structures.
• Traditional sintering methods (heat, solvents) have limitations.
• Subcritical carbon dioxide (CO2) was previously introduced as an alternative sintering method.

Purpose of the Study:

• To explore the effect of processing parameters on subcritical CO2 sintering of microsphere-based scaffolds.
• To identify optimal CO2 processing conditions for tunable scaffold properties.
• To evaluate the biocompatibility of CO2-sintered scaffolds.

Main Methods:

• Utilized gaseous or subcritical CO2 for scaffold fabrication.
• Investigated varying pressures (15-25 bar), poly(lactic acid-co-glycolic acid) (PLGA) compositions (lactic acid to glycolic acid ratios), and NaCl particle content.
• Assessed scaffold mechanical properties, morphology, and human umbilical cord mesenchymal stromal cell (hUCMSC) viability and penetration.

Main Results:

• Scaffold properties (stiffness, elastic moduli) were tunable by adjusting CO2 pressure, PLGA composition, and NaCl content.
• Higher stiffness was achieved at 25 bar with lower lactic acid ratios and no NaCl.
• Lower elastic moduli were observed at 15 bar with lower glycolic acid content and salt granules.
• hUCMSCs demonstrated successful penetration and viability on the scaffolds.

Conclusions:

• Subcritical CO2 sintering is a versatile and benign method for creating tunable microsphere-based tissue engineering scaffolds.
• Optimal CO2 processing parameters are dependent on the specific polymer and desired scaffold characteristics.
• This method presents a safer alternative to conventional heat or solvent-based sintering techniques.