Effect of cellulose nanocrystals on chitosan/PVA/nano β-TCP composite scaffold for bone tissue engineering application

The need for an ideal tissue construct has lead to the search of a myriad of polymer composites with desirable properties. The nature, location and type of tissue to be regenerated determines the type of material to be used. A bone construct has its own requirements such as osteoconductivity, mineralization tendency, synchronized degradation rate, osteogenic differentiation potential etc, which results in search of new possible combination of materials aimed to improve tissue response. The present study involves fabrication of Chitosan/Polyvinyl alcohol (PVA)/beta-Tricalcium Phosphate (beta-TCP)/Cellulose nanocrystals (CNC) porous composite by freeze drying process to be used as bone tissue engineering matrix. CNCs were isolated by acid hydrolysis of cellulose derived from pistachio shells. The prepared scaffold samples were characterized by Fourier-transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and X-RAY Diffraction analysis (XRD). The scaffolds exhibited refinement in pore morphology and increased mineralization tendency on increasing CNC concentration. Samples with 1% and 5% CNC concentration have deposited apatite crystals with Ca/P ratio of 1.61 and 1.66 which is very close to the stoichiometric ratio of natural bone apatite. Compressive modulus of CS/PVA/beta-TCP/CNC composite increased on increasing the CNC concentration to 5%. The highest cell viability was recorded in scaffolds with 5% CNC content. Though cell attachment tendency was observed in all samples but the samples with 5 and 10% CNC content demonstrated higher cell densities with significant calcium depositions when cultured for 72 h. Samples with 5% CNC concentration also possessed highest cell differentiation capabilities.