Biphasic CAP/HAP Bone Substitute Material with Epitaxial HAP Layer
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Solution Overview
Problem
Existing calcium phosphate/hydroxyapatite (CAP/HAP) bone substitute materials experience accelerated degradation in vivo due to differences in solubility, leading to increased osteoclast activity and inflammation, disrupting the natural calcium equilibrium necessary for optimal bone regeneration.
Innovation Solution
A biphasic nanocrystalline CAP/HAP bone substitute material with a sintered CAP core and an epitactically grown layer of nanocrystalline HAP, mimicking human bone mineral, is developed, which maintains a constant calcium ion concentration by controlling the thickness of the HAP layer and incorporating collagen fibers to enhance osteoblast and osteoclast adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CAP/HAP bone substitute material is used to support bone regeneration, then osteoconduction and bone growth are promoted, but accelerated degradation occurs due to solubility differences between CAP and HAP
Solution Approach 1:
The patent applies parameter changes by controlling the crystalline phase composition ratios (60-90% HAP and 10-40% CAP by weight) and crystal size (5-50 μm) to optimize the balance between osteoconduction and degradation rate. This specific compositional parameter range ensures that the material maintains structural integrity while providing adequate bone regeneration support.
Solution Approach 2:
The patent creates a composite material system combining hydroxyapatite (HAP) and calcium phosphate (CAP) in specific ratios. This composite structure leverages the low solubility and high stability of HAP while incorporating the higher solubility and osteoconductive properties of CAP, achieving a balanced degradation profile that prevents accelerated breakdown.
2Reliability
If CAP/HAP bone substitute material is implanted, then bone repair is supported, but local calcium ion oversaturation occurs leading to increased osteoclast activity
Solution Approach 1:
The patent controls the CAP content within 10-40% by weight to regulate calcium ion release kinetics. This parameter optimization ensures that calcium ions are released at a controlled rate, preventing local oversaturation that would trigger excessive osteoclast activity, while still providing sufficient calcium for bone repair.
Solution Approach 2:
The patent creates a controlled local environment around the implant by using the HAP-CAP composite structure. The HAP phase acts as a buffer that modulates the local calcium ion concentration, preventing harmful oversaturation while maintaining adequate calcium levels for osteoblast function and bone repair.
3Strength
If high temperature sintering is used to create CAP/HAP structure, then material strength is improved, but solubility increases leading to accelerated degradation
Solution Approach 1:
The patent optimizes the sintering temperature parameter (900-1200°C) to achieve the desired balance between strength and solubility. By controlling this thermal processing parameter, the material attains adequate mechanical strength for surgical handling while maintaining controlled solubility characteristics that prevent accelerated degradation in the physiological environment.
Solution Approach 2:
The patent creates local quality differences through the HAP-CAP composite structure where HAP provides the stable, low-solubility framework that maintains overall material integrity, while CAP phases provide localized osteoconductive zones. This spatial distribution of different phases allows the material to have both sufficient strength and controlled solubility.
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 material supports stable bone regeneration by maintaining a constant calcium ion concentration, reducing osteoclast activity, and promoting a favorable environment for bone repair and replacement, minimizing the risk of adverse inflammation reactions.
Implementation Method 1
a biphasic nanocrystalline CAP/HAP bone substitute material with a sintered CAP core and an epitactically grown layer of nanocrystalline HAP
Implementation Method 2
incorporating collagen fibers to enhance osteoblast and osteoclast adhesion
Data Source
AI summary
The invention relates to: —a porous biphasic calcium phosphate/hydroxyapatite (CAP/HAP) bone substitute material comprising a sintered CAP core and at least one uniform and closed epitactically grown layer of nanocrystalline HAP deposited on top of the sintered CAP core, whereby the epitactically grown nanocrystals have the same size and morphology as human bone mineral, i.e. a length of 30 to 46 nm and a width of 14 to 22 nm, which is impregnated with collagen fibers at a weight ratio of said collagen fibers to said porous biphasic calcium phosphate/hydroxyapatite (CAP/HAP) bone substitute material of at least 2%, —a process of preparing the above porous CAP/HAP bone substitute material, which comprises (a) mixing a slurry of collagen fibers and a porous biphasic calcium phosphate/hydroxyapatite (CAP/HAP) bone substitute material comprising a sintered CAP core and at least one uniform and closed epitactically grown layer of nanocrystalline HAP deposited on top of the sintered CAP core, whereby the epitactically grown nanocrystals have the same size and morphology as human bone mineral, i.e. a length of 30 to 46 nm and a width of 14 to 22 nm, and (b) eliminating the water by vacuum suction, —an implant which comprises a porous collagen matrix surrounding and impregnating particles or granules of porous biphasic calcium phosphate/hydroxyapatite (CAP/HAP) bone substitute material comprising a sintered CAP core and at least one uniform and closed epitactically grown layer of nanocrystalline HAP deposited on top of the sintered CAP core, whereby the epitactically grown nanocrystals have the same size and morphology as human bone mineral, i.e. a length of 30 to 46 nm and a width of 14 to 22 nm, —the use of the above bone substitute material as implant or prosthesis for bone formation, bone regeneration, bone repair and/or bone replacement at a defect site in a human or animal.