Shielded Bioactive Glass Scaffolds for Bone Regeneration
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Solution Overview
Problem
Current porous bioactive glass scaffolds face challenges due to low strength, poor handleability, and rapid crystallization when heated, making it difficult to create commercially available, amorphous, and rigid scaffolds for tissue repair and regeneration, especially for clinical use in orthopedic applications.
Innovation Solution
A method involving a glass or ceramic bead with an internal porous scaffold microstructure surrounded by an amorphous shield, which increases strength and flowability, allowing for enhanced degradability and tissue growth, using a process that involves crushing bioactive glass particles, forming agglomerates, and sintering them with rapid heating and cooling to suppress crystallization and create a shielded, porous structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If highly porous bioactive glass scaffolds are created to promote tissue growth, then tissue penetration and surface area for reaction are improved, but strength and handleability deteriorate
Solution Approach 1:
The scaffold is segmented into a porous internal microstructure and an external amorphous shield layer. The porous interior provides high surface area for tissue penetration and reaction, while the external shield segment provides structural strength and handleability, resolving the contradiction between porosity and strength.
Solution Approach 2:
The scaffold combines two distinct structural components: a porous bioactive glass microstructure for biological functionality and an amorphous shield layer for mechanical strength. This composite structure integrates the benefits of both high porosity and high strength in a single scaffold system.
2Ease of manufacture
If traditional heat treatment is applied to bond glass particles, then viscosity flow and bonding are improved, but crystallization occurs rapidly making rigid porous scaffolds difficult to produce
Solution Approach 1:
The glass composition parameters are specifically modified to achieve a narrow processing window where bonding can occur without crystallization. The glass transition temperature and viscosity characteristics are tuned to allow viscous flow bonding while suppressing crystal nucleation, enabling manufacture of rigid porous scaffolds.
Solution Approach 2:
The process exploits the glass transition phase change to enable bonding. By heating to the glass transition temperature range, the material transitions to a viscous state allowing particle bonding, then rapidly cools to lock in the amorphous structure before crystallization can occur, achieving both bonding and compositional stability.
3Ease of operation
If large glass particles (>500 μm) are used, then ease of handling is improved, but conversion to hydroxyapatite takes years due to small surface area to mass ratio
Solution Approach 1:
The scaffold utilizes a porous internal microstructure that provides high surface area to mass ratio throughout the entire particle volume. This porous architecture allows rapid penetration by body fluids and bone tissue, accelerating conversion to hydroxyapatite from years to weeks, while the external shield maintains handleability.
Solution Approach 2:
The structure nests a highly porous microstructure within an outer shell of appropriate size. The internal porous network provides rapid reaction surfaces while the external dimensions maintain ease of handling during surgical implantation, resolving the contradiction between handleability and conversion rate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting shielded scaffolds exhibit improved strength, handleability, and degradability, facilitating tissue growth and regeneration, while avoiding the limitations of traditional methods that result in rough, crystalline, and non-clinically approved products.
Implementation Method 1
Glasses with compositions similar to 45S5 and S53P4 crystallize rapidly when heated above each glasses respective glass transition temperature (Tg), making viscous sintering by traditional heat treatments difficult without crystallization.
Implementation Method 2
Glasses with compositions similar to 45S5 and S53P4 crystallize rapidly when heated above each glasses respective glass transition temperature (Tg), making viscous sintering by traditional heat treatments difficult without crystallization.
Data Source
AI summary
A glass, glass-ceramic, or ceramic bead is described, with an internal porous scaffold microstructure that is surrounded by an amorphous shield. The shield serves to protect the internal porous microstructure of the shield while increasing the overall strength of the porous microstructure and improve the flowability of the beads either by themselves or in devices such as biologically degradable putty that would be used in bone or soft tissue augmentation or regeneration. The open porosity present inside the bead will allow for enhanced degradability in-vivo as compared to solid particles or spheres and also promote the growth of tissues including but not limited to all types of bone, soft tissue, blood vessels, and nerves.