Improvement of bone filler materials using granular calcium sulfate dihydrate-gelatin-polycaprolactone composite

Calcium sulfate dihydrate (CSD) cement has been used as bone void filler and antibiotic carrier for many years. However, the main drawback of CSD cement is its brittleness that limits its handling property. The aim of this study is to fabricate granular CSD cement-gelatin-polycaprolactone (CSD-Gel-PCL) and evaluate its microstructure and mechanical behavior. To prepare CSD-Gel-PCL composite, granular CSD was prepared from calcium sulfate hemihydrate (CaSO4.0.5H2O; CSH) and distilled water with water/powder (W/P) ratio of 0.5. The CSD cement was crushed and sieved into 300-500 µm. The obtained granular CSD was then mixed with 3 wt.%, 5 wt.% and 7 wt.% gelatin solution which previously mixed with PCL (50 wt% PCL, 50 wt% gelatin), followed by freeze drying for 48 hours. The CSD granules were able to bind together after the addition of gelatin and PCL matrix. After freeze drying, the CSD granules were not easy to remove from the composite body. Scanning electron microscopy (SEM) analysis revealed that CSD granules were surrounded by polymer matrix in all 3 different specimens in which the higher gelatin concentration, the more the matrix found between the granules. Mechanical evaluation suggested that all of the specimens showed the same stress-strain curve pattern. The CSD-Gel-PCL composite with 7 wt% gelatin has the highest strength compared with the other specimens. Stress-strain curves indicated that combination of CSD granules, gelatin and PCL has produced bone filler with improved handling property.