Synthesis, characterization of chitosans and fabrication of sintered chitosan microsphere matrices for bone tissue engineering

The objective of the present study was to synthesize and characterize chitosans with different degrees of deacetylation (DDA%), prepare chitosan microspheres with controlled chemistry and geometry, and fabricate three-dimensional (3-D) chitosan matrices based on microspheres with appropriate pore size, porosity and mechanical properties suitable for bone tissue engineering applications. Chitosans with three DDA% of 69%, 79% and 97% were obtained using a thermomechanochemical technique by varying the applied pressure and NaOH solution concentration. The prepared chitosans were comprehensively characterized by proton nuclear magnetic resonance, elemental analysis, viscosity measurements, thermal analyses and X-ray diffraction. In addition, chitosan microspheres were prepared using an ionotropic gelation method. Three-dimensional chitosan matrices were fabricated via a sintered microsphere technique. Scanning electron microscopy revealed rough surfaces of the prepared chitosan microspheres. Mercury intrusion porosimetry revealed a porosity of 19.2% and a median pore diameter of 199.62 μm of the fabricated 3-D matrix. The compressive modulus of the sintered microsphere matrix (662.26 ± 54.53 MPa) was in the range of human cancellous bone (10–2000 MPa), making it suitable for bone tissue engineering applications.