Preparation and characterization of biodegradable nano hydroxyapatite–bacterial cellulose composites with well-defined honeycomb pore arrays for bone tissue engineering applications

Bacterial cellulose (BC), a nano fibrous hydrogel synthesized from non-pathogenic bacteria, is an excellent candidate scaffold for bone tissue engineering applications due to its biocompatibility, high purity and mechanical strength. However, BC is not biodegradable and possesses small pore sizes, which hinders the ingrowth of cells and thereby limits its potential as a bone tissue engineering scaffold. In this study, microporous BC (termed Porous BC) scaffolds with well-defined honeycomb pore arrays were prepared using a laser patterning technique. The BC scaffolds were modified using periodate oxidation to yield biodegradable oxidized BC scaffolds. In a unique manner, the BC scaffolds were then mineralized with nano hydroxyapatite (nano HA) to mimic the inorganic component of native bone tissue, improve bone cell compatibility, enhance mechanical properties, and control degradation. Results confirmed that sodium periodate oxidation successfully oxidized BC and Porous BC honeycomb pore arrays with 300 μm pore sizes with irregularly shaped 77 ± 15 nm nano HA and aggregated 200–500 nm nano HA were formed. BC and its composites displayed suitable mechanical properties for bone tissue engineering applications. The in vitro degradation study showed a significant 13–25 % loss of their dry mass in the oxidized BC composites thus confirming that the oxidized cellulose can biodegrade. Most importantly, the results also demonstrated that human-derived bone marrow mesenchymal stem cells (hMSCs) adhered to and were viable on the BC and its composites, thus, confirming their potential to serve as improved bone tissue engineering scaffolds. The novelty of the present study includes the precipitation of nano HA onto cellulose to promote hMSCs functions for improving orthopedic applications.