Preparation, characterization and osteoblastic activity of chitosan/polycaprolactone/in situ hydroxyapatite scaffolds

Calcium-deficient hydroxyapatite (cd-HA) crystals with a rod-like shape, 10-30 nm in diameter and 60150 nm in length, were prepared via a hydrothermal method in the presence of poly(acrylic acid) (PAA) (in situ HA). Scaffolds composed of chitosan (CS), polycaprolactone (PCL) and in situ HA were prepared by freeze-drying, using a formic acid/acetone mixture as a shared solvent. The mass fraction of in situ HA in the scaffolds ranged from 0 to 40%. FT-IR and XRD studies indicated that hydrogen bonding interactions existed among CS, PCL and in situ HA, which suppressed the crystallization of PCL. The mechanical results demonstrated that the CS/PCL composites had the maximum flexural stress (308.14 ± 8.86 MPa), which was significantly higher than 2.92 ± 0.02 MPa for the CS/in situ HA control. The effects of scaffolds on MC3T3-E1 cells were studied by measuring the viability, proliferation, adhesion, alkaline phosphatase activity, as well as mineralization assay. The WST-1 assay showed that in situ HA-loaded scaffolds had higher cell viability than CS/PCL scaffolds. SEM images of the cell-seeded scaffolds revealed a significant promotion of cell adhesion in in situ HA-loaded scaffolds. Moreover, ALP and mineralization were found to be enhanced in in situ HA-loaded scaffolds. All these results indicate that in situ HA-loaded scaffolds support cellular functions of osteoblastic cells and may serve as promising bone scaffolds.