Case Study: Hydroxyapatite and PCL

Hydroxyapatite and polycaprolactone blends have been previously investigated as scaffolds for bone tissue engineering [1]. In addition to its biocompatibility, hydroxyapatite offers osteoconductive properties. However, with a high melting temperature and insolubility in water, hydroxyapatite presents challenges for extrusion bioprinting. When mixed with polycaprolactone, which exhibits a low melting point, the blended materials can be printed together [1]. Below are sample print parameters for a hydroxyapatite and polycaprolactone blend with the Allevi 1.

First, polycaprolactone (PCL) was melted on a glass plate at 100°C. Very carefully, 20% (w/v) hydroxyapatite was mixed into the PCL. Then, this mixture was loaded into an allevi metal 10 ml BD syringe. A metal 27 gauge fisnar needle was placed onto the tip of the syringe and loaded into the first extruder of the Allevi 1. The extruder was then heated to 120°C. A lattice, imaged below, was completed at a pressure of 100 PSI with an approximate resolution of 0.3 – 0.4 mm.

 Figure 1:: Printed lattice with above parameters.

Figure 1:: Printed lattice with above parameters.

*Critical step: Your needle can have significant effects on print settings. Be sure to use the suggested needle type or re-characteriz print parameters.
Speed (mm/s) Layer Height (mm) Nozzle Diam (mm) Gauge Pressure (psi) Print Temp (C)
0.5 0.2 0.3 27 Tapered 100 120