Feasibility study of novel bioactive glass prepared from bagasse and cassava rhizome for bone tissue engineering applications

Bioactive glass prepared from bagasse and cassava rhizome exhibits interesting properties in addition to low cost and being environmentally friendly. Two glass series based on B2O3-P2O5-Na2O-CaO-BG and B2O3-P2O5-CaO-CR, where BG is bagasses and CR is cassava rhizome, were fabricated by a meat quenching technique. A feasibility study was undertaken using bagasse and cassava rhizome as novel bioactive glass and results were evaluated physically, mechanically, structurally, morphologically and in terms of degradation properties. The densities of the prepared glasses were measured and calculated based on, respectively, Archimedes’ principle and additive rule, and results were studied and compared. The ultrasonic velocities of the glass samples with different mix proportions of bagasse and cassava rhizome were measured based on a pressure-controlled ultrasonic technique at the frequency of 4 MHz through normal and angle probes. The elastic moduli, Poisson’s ratio and microhardness were calculated from an acoustic velocity and a density data of the glass samples. Vickers hardness tester was also applied to determine the microhardness of the glass using the applied load of 0.98 N. A set of the novel glasses for bone tissue engineering was tested in vitro bioactivity before and after immersion in the simulated body fluid (SBF) solution during exposure at 37๐C for 1, 7 and 14 days. The structural and morphological changes including bone bonding ability were assessed by performing XRD, FTIR and SEM measurements. The degradation behavior of the glass samples and pH change of SBF solution were also considered in this work. The results found that the addition of bagasses and cassava rhizome leads to an increase of the densities, ultrasonic wave velocities, elastic moduli and microhardness values in all prepared glasses. The values of microhardness obtained from both techniques were compared and a good correlation was observed. The results of the weight loss and pH value of the solution increased with longer time periods. The addition of bagasse and cassava rhizome into the glasses leads to a decrease of the dissolution rate. Before soaking in the SBF solution, XRD data was observed to confirm the amorphous nature of the glasses while FTIR spectra supported the internal structural units of the prepared glass, corresponding to main borate groups. Additionally the surface morphology before immersion showed a flat surface with deep grooves. After immersion, the XRD patterns illustrated some peaks corresponding to calcium phosphate phases in the form of brushite and hydroxyapatite. Likewise, the FTIR spectra about 550-610 cm-1 and 980-1060 cm-1 indicated the P-O bonds related to the calcium phosphate layer formation. Moreover, the SEM images showed the agglomeration of many small rounded particles on the glass surface, indicating the formation of calcium phosphate layers. These XRD, FTIR and SEM results confirmed the formation of hydroxyapatite or bone bonding ability on glass surfaces after immersion in the SBF solution.