Interconnected Porous Hydroxyapatite Research Articles

Design of three‐dimensional interconnected porous hydroxyapatite ceramic‐based composite phase change materials for thermal energy storage

In this article, three-dimensional connected porous hydroxyapatite ceramics (PHCs) were prepared by using the Pickering emulsion template, which possessing controlled pore structure simply by adjusting the solid content from 35 to 55 wt%. The polyethylene glycol (PEG) and PHCs were compounded by vacuum impregnation to acquire composite phase change materials (CPCMs) with admirable shape stability. The SEM and EDS images showed that PEG was successfully adsorbed in the pore, and the results of FT-IR, XRD, TGA, and thermal cycles test, demonstrated the CPCMs possessed satisfactory chemical stability, favorable thermal stability, and wonderful thermal reliability. The maximum package ratio obtained was 66 wt%, which was supported by the PHC sample prepared with a solid content of 40 wt%. Moreover, the phase transition temperature and latent heat during melting and solidification were 53.41°C and 117.5 J/g, 36.49°C and 111.1 J/g, respectively. Therefore, the prepared PCM composites had a controlled pore structure, stable chemical properties, high latent heat, and excellent thermal reliability, making it a reliable application of thermal energy storage.

Biomimetic 3D Printing of Hierarchical and Interconnected Porous Hydroxyapatite Structures with High Mechanical Strength for Bone Cell Culture

Human bone demonstrates superior mechanical properties due to its sophisticated hierarchical architecture spanning from the nano/microscopic level to the macroscopic. Bone grafts are in high demand due to the rising number of surgeries because of increasing incidence of orthopedic disorders, non‐union fractures, and injuries in the geriatric population. The bone scaffolds need to provide porous matrix with interconnected porosity for tissue growth as well as sufficient strength to withstand physiological loads, and be compatible with physiological remodeling by osteoclasts/osteoblasts. The‐state‐of‐art additive manufacturing (AM) technologies for bone tissue engineering enable the manipulation of gross geometries, for example, they rely on the gaps between printed materials to create interconnected pores in 3D scaffolds. Herein, the authors firstly print hierarchical and porous hydroxyapatite (HAP) structures with interconnected pores to mimic human bones from microscopic (below 10 µm) to macroscopic (submillimeter to millimeter level) by combining freeze casting and extrusion‐based 3D printing. The compression test of 3D printed scaffold demonstrates superior compressive stress (22 MPa) and strain (4.4%). The human mesenchymal stromal cells (MSCs) tests demonstrate the biocompatibility of printed scaffold.

Fabrication and evaluation of interconnected porous carbonate apatite from alpha tricalcium phosphate spheres.

Carbonate apatite (CO3 Ap) blocks have attracted considerable attention as an artificial bone substitute material because CO3 Ap is a component of and shares properties with bone, including high osteoconductivity and replacement by bone similar to autografts. In this study, we fabricated an interconnected porous CO3 Ap block using α-tricalcium phosphate (TCP) spheres and evaluated the tissue response to this material in a rabbit tibial bone defect model. Interconnected porous α-TCP, the precursor of interconnected porous CO3 Ap, could not be fabricated directly by sintering α-TCP spheres. It was therefore made via a setting reaction with α-TCP spheres, yielding interconnected porous calcium-deficient hydroxyapatite that was subjected to heat treatment. Immersing the interconnected porous α-TCP in Na-CO3 -PO4 solution produced CO3 Ap, which retained the interconnected porous structure after the dissolution-precipitation reaction. The diametral tensile strength and porosity of the porous CO3 Ap were 1.8 ± 0.4 MPa and 55% ± 3.2%, respectively. Both porous and dense (control) CO3 Ap showed excellent tissue response and good osteoconductivity. At 4 weeks after surgery, approximately 15% ± 4.9% of the tibial bone defect was filled with new bone when reconstruction was performed using porous CO3 Ap; this amount was five times greater than that obtained with dense CO3 Ap. At 12 weeks after surgery, for porous CO3 Ap, approximately 47% of the defect was filled with new bone as compared to 16% for dense CO3 Ap. Thus, the interconnected porous CO3 Ap block is a promising artificial bone substitute material for the treatment of bone defects caused by large fractures or bone tumor resection. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 269-277, 2019.

Application of interconnected porous hydroxyapatite ceramic block for onlay block bone grafting in implant treatment: A case report.

Autogenous block bone grafting as treatment for alveolar ridge atrophy has various disadvantages, including a limited availability of sufficiently sized and shaped grafts, donor site morbidity and resorption of the grafted bone. As a result, interconnected porous hydroxyapatite ceramic (IP-CHA) materials with high porosity have been developed and used successfully in orthopedic cases. To the best of the author's knowledge, this is the first report of clinical application of an IP-CHA block for onlay grafting for implant treatment in a patient with horizontal alveolar atrophy. The present study performed onlay block grafting using an IP-CHA block to restore bone volume for implant placement in the alveolar ridge area without collecting autogenous bone. Dental X-ray findings revealed that the border of the IP-CHA block became increasingly vague over the 3-year period, whereas CT scanning revealed that the gap between the block and bone had a smooth transition, indicating that IP-CHA improved the process of integration with host bone. In follow-up examinations over a period of 5 years, the implants and superstructures had no problems. An IP-CHA block may be useful as a substitute for onlay block bone grafting in implant treatment.

Fabrication of interconnected porous calcium-deficient hydroxyapatite using the setting reaction of α tricalcium phosphate spherical granules

Abstract Interconnected porous calcium-deficient hydroxyapatite (cdHAp) blocks may be an ideal biomaterial to repair bone defects because of their greater similarity to human bone than that of sintered hydroxyapatite (HAp) with respect to calcium content and crystallinity. In particular, the interconnected pores in cdHAp may provide pathways for cell migration and tissue ingrowth. In this study, the feasibility of fabricating interconnected porous cdHAp blocks through the setting reaction of alpha-tricalcium phosphate (αTCP) spherical granules was investigated. It was found that regulation of cdHAp formation was important to fabricate interconnected porous cdHAp blocks. That is, cdHAp needed to precipitate preferentially at the contacting areas between αTCP spherical granules. Exposure of αTCP spherical granules to steam under appropriate pressure was effective for this purpose. When αTCP spherical granules were immersed in water at 100 °C, the setting reaction resulted in dense cdHAp blocks because of the free crystal growth of cdHAp in water. Therefore, steam was used to localize the water at the contacting areas between αTCP spherical granules, which was driven by the surface tension of the water. Without an applied load, no setting reaction was observed when αTCP spherical granules were exposed to steam at 100 °C for 12 h. In contrast, under a load of 20 MPa, cdHAp precipitated to bridge spherical granules, providing an interconnected porous cdHAp block. The porosity and diametral tensile strength of this block were approximately 63% and 1.5 MPa, respectively.

Stability of Implants Placed in Bone Reconstructed with Block-type Interconnected Porous Hydroxyapatite

Stability of Implants Placed in Bone Reconstructed with Block-type Interconnected Porous Hydroxyapatite

Porous 3D bioscaffolds by adaptive foam reticulation

Highly interconnected and 3D porous hydroxyapatite scaffolds with controllable macroporosity and microporosity have been produced using the adaptive foam reticulation technique, combining foam reticulation and freeze casting methodologies. Process optimized macropores were generated using a polymeric template while micropores are introduced by the sublimation of a porogen, in this instance camphene. The macropore (100–600 µm) and strut (20–100 µm) sizes of the bioceramic produced compares favorably with the template pore (200–600 µm) and strut (30–80 µm) sizes. X-ray diffraction analysis indicated a phase change from hydroxyapatite to whitlockite, a calcium-deficient phosphate incorporating magnesium and iron ions. Increasing the number of coatings and/or sintering temperature resulted in the increase of scaffold strength while reducing the pore size. Variations to the amount of porogen did not affect the macrostructure of the scaffolds and led to the controllable introduction of microporosity to the struts. Osteoblast-like MG-63 cell culture and assay tests indicated that the scaffolds are not cytotoxic and suitable for use as bone grafts.

Aesthetic recovery of alveolar atrophy following autogenous onlay bone grafting using interconnected porous hydroxyapatite ceramics (IP-CHA) and resorbable poly-L-lactic/polyglycolic acid screws: case report.

BackgroundOnlay bone grafting techniques have some problems related to the limited volume of autogenous grafted bone and need for surgery to remove bone fixing screws. Here, we report a case of horizontal alveolar ridge atrophy following resection of a maxillary bone cyst, in which autogenous onlay bone grafting with interconnected porous hydroxyapatite ceramics (IP-CHA) and bioresorbable poly-L-lactic/polyglycolic acid (PLLA-PGA) screws was utilized.Case presentationA 51-year-old man had aesthetic complications related to alveolar atrophy following maxillary bone cyst extraction. We performed onlay grafting for aesthetic alveolar bone recovery using IP-CHA to provide adequate horizontal bone volume and PLLA-PGA screws for bone fixing to avoid later damage to host bone during surgical removal. During the operation, an autogenous cortical bone block was collected from the ramus mandibular and fixed to the alveolar ridge with PLLA-PGA screws, then the gap between the bone block and recipient bone was filled with a granular type of IP-CHA. Post-surgery orthopantomograph and CT scan findings showed no abnormal resorption of the grafted bone, and increased radiopacity, which indicated new bone formation in the area implanted with IP-CHA.ConclusionOur results show that IP-CHA and resorbable PLLA-PGA screws are useful materials for autogenous onlay bone grafting.

ポリリン酸吸着人工骨の開発

骨量の減少は補綴治療の予後に対し大きな懸念要因となり，自家骨に代わる骨増生のためのバイオマテリアルの開発が望まれている．そこで，既存のマテリアルをハイブリッドさせた予知性の高く幅広い普及が可能な新規人工骨の開発に取り組んできた．中鎖型ポリリン酸は，線維芽細胞成長因子を安定化させ骨芽細胞の石灰化を促進する作用を有しており，骨再生への展開が期待できる．この中鎖型ポリリン酸を連通多孔性ハイドロキシアパタイトに吸着させた新規人工骨は，骨欠損部での骨形成促進効果を示した．そこで，新規人工骨としてのポリリン酸吸着人工骨の開発について，これまでに得られた知見を総括して報告する．

Efficient modification of the surface properties of interconnected porous hydroxyapatite by low-pressure low-frequency plasma treatment to promote its biological performance

Dielectric barrier discharge plasma treatment at low pressure is found to significantly improve the biological performance of artificial bones made of interconnected porous calcium hydroxyapatite (IP-CHA). One of the essential parameters associated with their biological performance is hydrophilicity of their exterior surfaces as well as surfaces of inner pores. It is found that plasma treatment at low pressures is highly effective in making the inner pore surfaces more hydrophilic. Preliminary in vivo experiments of plasma-treated IP-CHA artificial bones in rats have shown fast formation of blood vessels in their inner pores, implying the increase in osteoconductivity due to the plasma treatment.

Three‐dimensional porous bioscaffolds for bone tissue regeneration: Fabrication via adaptive foam reticulation and freeze casting techniques, characterization, and cell study

Highly interconnected and 3D porous bioactive hydroxyapatite (HAP) and Bioglass scaffolds have been fabricated by an adaptive version of camphene based foam reticulation (ARM) and camphene freeze casting (CFC) methods. Controlled sublimation of camphene during freeze casting at -78°C produced process optimized bioscaffolds with open, uniform, and interconnected porous structures. HAP and Bioglass scaffolds with desired porosity, pore size, and microtopography were successfully fabricated using polyurethane foam templates of appropriate structures. Macropores of 50-1100 μm with microporosity of 1-10 μm, known to facilitate cell adhesion and proliferation, were obtained. Compressive yield strength of 0.8 MPa close to the upper range of cancellous bone was achieved. The mean compressive strength of HAP scaffolds compared favorably with the theoretical model of porosity variation with strength and was higher than reported values. The nature of pore development, morphology, porosity, crystal structure, chemical composition, and thermal behavior were characterized using scanning electron and optical microscopy, X-ray diffraction, thermal analysis, and mercury porosimetry. These scaffolds are suited for nonstructural graft and were not cytotoxic in vitro when osteoblast-like MG63 cells were cultured with the HAP constructs. The cells attached indicated by cell metabolic activity by resazurin assay and spread well when cultured on the surface of the materials.

Clinical evaluation of novel interconnected porous hydroxyapatite ceramics (IP-CHA) in a maxillary sinus floor augmentation procedure

The aim of this study was to evaluate the clinical behavior and the histological aspects of interconnected porous hydroxyapatite ceramics (IP-CHA) in maxillary sinus floor augmentation procedures. A 59-year-old female patient received one-stage implant integration with right maxillary sinus floor augmentation with mixture grafts from the cortical bone and IP-CHA. Implant stability of each fixture increased at 9 months after fixture installation compared with the first operation and adequate fixation of each fixture could be obtained. Histological analysis revealed there was new bone formation in the majority of pores of IP-CHA. Moreover, on a panoramic radiograph taken at 33 months the mixture grafts were distinctly observed as a radiopacity in the right sinus cavity, and marked absorption of mixture grafts was not found. Our results suggest that IP-CHA has the potential to provide a major scaffold for osteoprogenitor cells and is a useful grafting material for maxillary sinus augmentation.

Biomechanical evaluation of porous bioactive ceramics after implantation: micro CT-based three-dimensional finite element analysis

Hydroxyapatite ceramics have been widely investigated for bone regeneration due to their high biocompatibility. However, few studies focus on their mechanical characteristics after implantation. In this study, the finite element (FE) method was used to evaluate the mechanical properties of a fully interconnected porous hydroxyapatite (IPHA) over time of implantation. Based on the micro-CT images obtained from the experiments dealing with IPHA implanted into rabbit femoral condyles, three-dimensional FE models of IPHA (1, 5, 12, 24, and 48 weeks after implantation) were developed. FE analysis indicated that the elastic modulus gradually increased from 1 week and reached the peak value at 24 weeks, and then it kept at high level until 48 weeks postoperatively. In addition, as a local biomechanical response, strain energy density became to distribute evenly over time after the implantation. Results confirmed that the mechanical properties of IPHA are strongly correlated to bone ingrowth. The efficiency of the proposed numerical approach was validated in combination with experimental studies, and the feasibility of applying this approach to study such implanted porous bioceramics was proved.

Improvement of Hydrophilicity of Interconnected Porous Hydroxyapatite by Dielectric Barrier Discharge Plasma Treatment

Dielectric barrier discharge plasma treatment has been found to significantly improve hydrophilicity of the surfaces of interconnected porous calcium hydroxyapatite (IP-CHA), particularly that of wall surfaces of the internal pores. IP-CHA has been clinically used as a material for bone substitutes in bone tissue regeneration. Higher hydrophilicity of IP-CHA obtained in this method is expected to further increase the osteoconductivity of IP-CHA.

Preparation of highly interconnected porous hydroxyapatite scaffolds by chitin gel-casting

In this study, a simple and effective method for producing highly interconnected porous hydroxyapatite (HA) scaffolds was developed by combining gel-casting, particle-leaching and extrusion techniques. Chitin (CT) sol was used to disperse HA particles and wax spheres were introduced as porogens for their excellent deformability. In extrusion process, the accumulated wax spheres in point-to-point contact can transform into surface-to-surface contact by means of the extrusion pressure. Thus, the obtained porous HA scaffolds exhibited an interconnected channel network after leaching out of the porogens. The results showed that the scaffolds prepared by different size of wax spheres exhibited nearly the same volumetric porosity of about 86%, while the compressive strengths decreased as the pore size increased. Therefore, the method developed can be used to effectively tailor the pore size of HA scaffolds while maintaining a high porosity. The highly porous HA scaffolds with excellent interconnectivity are expected to be a promising bone substitute in clinical practice.

Preparation of porous scaffold from hydroxyapatite powders

Hydroxyapatite (HA) powder was prepared by wet chemical method. The hydroxyapatite phase was stable up to 1250 °C without decomposition to beta-tricalcium phosphate. Interconnected porous hydroxyapatite scaffold resembling trabecular bone structure was developed from polymeric replica sponge method. The prepared scaffold has 60 vol.% porosity having a major fraction of ~ 50–125 μm pore diameter. The pore content, pore morphology, pore interconnectivity of scaffold and their compressive strength were dependent on the solid loading and binder content. In-vitro bioactivity and bioresorbability confirmed the feasibility of the developed scaffolds.

Effect of hyperbaric oxygen therapy on bone prefabrication in rats

This experimental study aimed to create a prefabricated vascularized bone graft using the interconnected porous coralline hydroxyapatite ceramic by combining vascular bundle implantation, mesenchymal stem cells, and hyperbaric oxygen therapy (HBOT) administration in a rat model. Forty-five male Sprague-Dawley rats were divided into three groups, each containing 15 rats. The hydroxyapatite ceramics were vascularized by the superficial inferior epigastric artery and vein in all groups. These vessels passed through the hole of the hydroxyapatite blocks. In Group 2, mesenchymal stem cells were administered into the hydroxyapatite. In Group 3, both mesenchymal stem cells and HBOT were administered. The presence and density of any new bone formation and neovascularization were evaluated by radiography, microangiography, scintigraphy, biochemical analysis, and histomorphometry. Neovascularization and bone formation were significantly greater in Group 3, in which both mesenchymal stem cells and HBOT were applied, than the other groups. HBOT enhances neovascularization and osteogenesis, thus HBOT can provide optimal and faster prefabrication of a vascularized bone graft.

Clinical experience of novel interconnected porous hydroxyapatite ceramics for the revision of tumor prosthesis: a case report

BackgroundAs for being cautious with tumor prostheses, revision of uncemented tumor prostheses in particular, it is necessary to remove cortical bone from the stem circumference with a chisel when the stem is extracted. This assures that bone in-growth will occur within the stem in itself. As a result, re-substitution of mass autogenous bone graft round a new stem is subsequently necessary. When rivision of uncemented tumor prosthesis of distal femur was performed, we evade fibula transplant by transplanting interconnected porous hydroxyapatite ceramic (IP-CA: Neobone) with a self bone, and reports its experience with the case that acquired enough strength.Case reportIn this report, we present the case of a 27-year-old female with stem breakage of tumor prosthesis and do revision surgery for prosthetic failure. In the case of revision surgery, autologous bone and Neobone were mixed, and this was transplanted to stem circumference. The Radiological Evaluation System of the ISOLS showed excellent results for all items. She can walk without using a cane or orthosis, and the score of the MSTS is 80%.ConclusionWhen revision of uncemented tumor prostheses of the distal femur was performed, we avoided fibula graft by using Neobone with the patient's own bone tissue. Our experience with this case may indicate that adequate strength is achieved.

Improving mechanical and biological properties of macroporous HA scaffolds through composite coatings

Interconnected porous hydroxyapatite (HA) scaffolds are widely used for bone repair and replacement, owing to their ability to support the adhesion, transfer, proliferation and differentiation of cells. In the present study, the polymer impregnation approach was adopted to produce porous HA scaffolds with three-dimensional (3D) porous structures. These scaffolds have an advantage of highly interconnected porosity (≈85%) but a drawback of poor mechanical strength. Therefore, the as-prepared HA scaffolds were lined with composite polymer coatings in order to improve the mechanical properties and retain its good bioactivity and biocompatibility at the same time. The composite coatings were based on poly( d, l-lactide) (PDLLA) polymer solutions, and contained single component or combination of HA, calcium sulfate (CS) and chondroitin sulfate (ChS) powders. The effects of composite coatings on scaffold porosity, microstructure, mechanical property, in vitro mineralizing behavior, and cell attachment of the resultant scaffolds were investigated. The results showed that the scaffolds with composite coatings resulted in significant improvement in both mechanical and biological properties while retaining the 3D interconnected porous structure. The in vitro mineralizing behaviors were mainly related to the compositions of CS and ChS powders in the composite coatings. Excellent cell attachments were observed on the pure HA scaffold as well as the three types of composite scaffolds. These composite scaffolds with improved mechanical properties and bioactivities are promising bone substitutes in tissue engineering fields.

Gadolinium-enhanced MRI evaluation of the vascular ingrowth into inter-connected porous hydroxyapatite ceramic grafted in juxta-articular intraosseous cystic lesions of patients with rheumatoid arthritis

Gadolinium-enhanced MRI evaluation of the vascular ingrowth into inter-connected porous hydroxyapatite ceramic grafted in juxta-articular intraosseous cystic lesions of patients with rheumatoid arthritis