NATURAL BIOSILICA AS AN INDEX FOR BONE HEALING: Invited Keynote

Diatoms are unicellular microalgae whose cell walls are composed of remarkably uniform, hierarchical micro/nanopatterned, amorphous biosilica that cannot be replicated synthetically. Each species hosts its own unique morphology which is identically replicated generation-to-generation. There are currently estimated to be over 200,000 different diatom species, each with their own unique shape and morphology. This offers a huge array of surface topographies, particle sizes and shapes, each with the same silica precursor. Our research to date has shown that diatom-biosilica is non-cyctotoxic to J774.2 macrophages and hBMSC cells and does not invoke an immunological response or organ toxicity (kidney, spleen and liver) when tested in a murine model. Before testing diatom-biosilica in vivo in an animal fracture model, methods to incorporate the frustules into the defect are being investigated. Two methods have been developed 1) using a bioresorbable hydrogel and 2) 3-D printed polymer-biosilica scaffolds. Both methods have shown promising results with enhanced mechanical properties with the addition of the diatom-biosilica. Work is ongoing to further map and quantify the role of surface topography and chemical cues on cell fate through the systematic in vitro studies of different species of diatom-biosilica.