Rheological Behavior and Injectability Properties of Injectable PEGs/Glycerol/Bioactive Glass-Based Bone Grafts Incorporated with Denosumab Drug

In this study, injectable bone graft putty samples were developed using fine and coarse melt-quenched 45S5 bioactive glass (BG) incorporated a carrier system composed of glycerol and different average molecular weights polyethylene glycol (PEGs). Selected putty samples were incorporated with different amount Denosumab (5-10 %wt.), a bone treatment drug, to investigate its influence on the rheological behavior and flow properties of the putty samples with mathematical modelling. All PEGs/glycerol/45S5 putty samples exhibited viscoelastic (G′> G″) and pseudoplastic (n<1) behavior with viscosity required for optimal flow remained below 1000 Pa∙s. Viscosity value and thixotropic area of putty samples were increased proportionally with high BG content and smaller-sized BG in putty. All putty samples showed over 98% injectability through a 12G cannula, suggesting a potential for clinical suitability. However, injectability decreased with smaller cannula, dropping to 34.7%–58.3% in 19G, and further decreasing at 23G for higher BG content. Incorporation of Denosumab preserved viscoelasticity and injectability yet modified the flow behavior (shifting from pseudoplastic to more Newtonian with high Denosumab content) while also reducing viscosity and thixotropic area values. Among all, putty containing low amount of Denosumab and smaller-sized BG exhibited the most suitable in about injectability and rheological features. All putty samples fitted with Power law and Herschel–Bulkley rheology models (R2>0.95). This study highlights the influence of Denosumab on flowability and rheological relationships in samples and suggests potential enhancements in bioactivity by synergetic dual effect with both BG and Denosumab in minimally invasive bone treatments as injectable bone graft systems.