Design of sol-gel bioactive glasses: Towards tailored architecture and ion-supply for bone tissue regeneration

Abstract

This paper reports the synthesis of borosilicate bioactive glasses nanoparticles containing ions of interest (calcium, strontium or silver ions) for the purpose of bone tissue regeneration using a modified Stöber method and their shaping by robocasting to produce macroporous grid-like architectures with controlled interconnected porosity. Main focus is on the design of a paste formulation, the optimization of the robocasting process to produce 3D scaffolds and ion release from the sintered scaffold in solution. Pastes were developed (40 vol% powder loading), characterized, and extruded layer-by-layer to form three-dimensional scaffolds with a grid-like macrostructure (400 μm diameter of the rods). After drying under controlled atmosphere, scaffolds were sintered. The sintering study revealed that the addition of silver reduced the densification point of the borosilicate glass. After immersion in a buffer solution, ionic release (Si, B and Sr) of the sintered scaffold was evaluated, and compared with the synthetized powder. The shaping process did not affect Sr dissolution. This controllable ion-release behavior of the scaffolds are promising for their therapeutic application.

Keywords

• Bioactive glasses
• Robocasting
• Sol-gel synthesis
• Additive manufacturing
• Scaffolds
• Bone tissue regeneration