Tricalcium Phosphate Composite Scaffolds Research Articles

Effect of Silicon Dioxide and Magnesium Oxide on the Printability, Degradability, Mechanical Strength and Bioactivity of 3D Printed Poly (Lactic Acid)-Tricalcium Phosphate Composite Scaffolds.

Poly (lactic acid) (PLA) is a biodegradable polyester that has been exploited for a variety of biomedical applications, including tissue engineering. The incorporation of β-tricalcium phosphate (TCP) into PLA has imparted bioactivity to the polymeric matrix. We have modified a 90%PLA-10%TCP composite with SiO2 and MgO (1, 5 and 10 wt%), separately, to further enhance the material bioactivity. Filaments were prepared by extrusion, and scaffolds were fabricated using 3D printing technology associated with fused filament fabrication. The PLA-TCP-SiO2 composites presented similar structural, thermal, and rheological properties to control PLA and PLA-TCP. In contrast, the PLA-TCP-MgO composites displayed absence of crystallinity, lower polymeric molecular weight, accelerated degradation ratio, and decreased viscosity within the 3D printing shear rate range. SiO2 and MgO particles were homogeneously dispersed within the PLA and their incorporation increased the roughness and protein adsorption of the scaffold, compared to a PLA-TCP scaffold. This favorable surface modification promoted cell proliferation, suggesting that SiO2 and MgO may have potential for enhancing the bio-integration of scaffolds in tissue engineering applications. However, high loads of MgO accelerated the polymeric degradation, leading to an acid environment that imparted the composite biocompatibility. The presence of SiO2 stimulated mesenchymal stem cells differentiation towards osteoblast; enhancing extracellular matrix mineralization, alkaline phosphatase (ALP) activity, and bone-related genes expression. The PLA-10%TCP-10%SiO2 composite presented the most promising results, especially for bone tissue regeneration, due to its intense osteogenic behavior. PLA-10%TCP-10%SiO2 could be used as an alternative implant for bone tissue engineering application.

Preparation of Porous Poly(Lactic Acid)/Tricalcium Phosphate Composite Scaffolds for Tissue Engineering

The development of bioactive and composite materials for tissue engineering applications is being investigated worldwide. Many approaches have been published by including combinations of resorbable polymers with hydroxyapatite (HA), tricalcium phosphate (TCP), bioactive glasses and glass-ceramics in different scaffolds architectures. Taking into account these antecedents, porous polylactic acid (PLA)/TCP composites were fabricated by employing dissolution-leaching technic from PLA/chloroform solution (10, 15, and 20 wt % of TCP). Composite scaffolds exhibited porosity values 1.3 times higher when compared to PLA foams. Their bioactive response of the composite foams after immersion in a simulated body fluid (SBF) was studied by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR-ATR). By XRD analysis, diffraction peaks attributed to hydroxyapatite deposition were observed; and by FTIR-ATR, new absorption bands corresponding to HA were detected. Regarding mechanical properties, an increasing tendency on elastic Young's modulus values was observed at higher TCP concentrations. These results envision the feasibility of using these composites as precursors for bone tissue materials engineering.

Osteogenic differentiation ability of human mesenchymal stem cells on Chitosan/Poly (Caprolactone)/nano beta Tricalcium Phosphate composite scaffolds

Our work depicts the development and characterization of Chitosan/Poly (caprolactone)/nano beta-Tricalcium phosphate (CS/PCL/β-TCP) porous composite scaffolds by freeze drying method. Addition of PCL to CS/β-TCP composite scaffolds had significantly increased the compressive strength besides decelerating the degradation rate. Human mesenchymal stem cells (hMSCs) were chosen to assess in-vitro biocompatibility of the prepared scaffolds in terms of cell viability, cell attachment and proliferation by MTT assay, SEM and DNA Quantification assays respectively. Further, increased osteogenic differentiation assay results (Alkaline Phosphatase assay and Total calcium content) revealed the role of β-TCP in composite scaffolds. Altogether, results suggest the potentiality of prepared porous freeze dried composite scaffolds in bone tissue engineering applications.

A Preliminary Study of the <i>In Vitro</i> Biocompatibility Testing of Silk Fibroin/Alpha Tricalcium Phosphate Composite Scaffolds for Bone Tissue Engineering

Silk fibroin is a natural biodegradable polymer that has been demonstrated for use as scaffolds for bone tissue engineering. To improve the osteoconductivity and the osteoinductivity of silk fibroin scaffolds, ceramics were added. α-tricalcium phosphate (α-TCP) is the expected ceramic that useful for scaffolds for bone tissue engineering either alone or blended with silk fibroin. From the previous study, we evaluated the mechanical properties of three-dimensional porous silk fibroin/ α-TCP scaffolds and concluded that the scaffolds containing 8% (w/w) α-TCP exhibited the highest compressive modulus. The objective of this study was to evaluate the biological properties of three-dimensional porous silk fibroin/α-TCP scaffolds. The scaffolds were constructed using a solvent casting and salt leaching technique. The hybrid strain of degummed Thai silk fibroin, Nangnoi Srisaket 1 x Mor, was dissolved in hexafluoroisopropanol at 16% (w/v). α-TCP was incorporated to produce 4, 8, 12, and 16 wt% solution. Sucrose (particle size 250-450 μm; sucrose/silk fibroin = 8.5/1 w/w) was used as a porogen. Human gingival fibroblasts (passage 5) were cultured in these scaffolds. After 72 h, the biocompatibility of seeded scaffolds was evaluated under the inverted phase contrast microscopy. Cell proliferation was determined by DNA assays and scanning electron microscopy. The images from inverted phase contrast microscopy revealed the human gingival fibroblasts can be attached at the surface of scaffolds in all groups. The results from the DNA assays showed that the number of human gingival fibroblasts was increased as the culture period was prolonged but was not as the increasing of α-TCP. At 120 h, the scaffolds containing 8% (w/w) α-TCP exhibited the highest cell number. The scanning electron microscope images at 24, 72, and 120 h after cell culturing presented human gingival fibroblasts can be expanded well and exhibited the normal morphology. The results suggested that the scaffolds containing 8% (w/w) α-TCP may be a potential candidate for bone tissue engineering applications.

Porous Silk Fibroin/Alpha Tricalcium Phosphate Composite Scaffolds for Bone Tissue Engineering: A Preliminary Study

Scaffolds with mechanical properties that mimic the tissue to be restored are critical to maintain the morphology and function of a scaffold after implantation and during tissue regeneration. Silk fibroin (SF), a protein from the Bombyxmori silk worm cocoon, is currently employed in the biomedical field and tissue engineering. The objective of this study was to construct three-dimensional porous silk fibroin/alpha tricalcium phosphate scaffolds for bone tissue engineering application. The scaffolds were fabricated using a solvent casting and salt leaching technique. The hybrid strain of degummed Thai silk fibroin, Nangnoi Srisaket 1 x Mor, was dissolved in hexafluoroisopropanol at 16% (w/v). Alpha tricalcium phosphate (α-TCP) was incorporated to produce 4, 8, 12, and 16 wt% solution and sucrose (particle size 250-450 μm; sucrose/silk fibroin = 8.5/1 w/w) was used as a porogen. The microstructure and pore size, calcium and phosphorus contents, and compressive modulus were evaluated. The scanning electron microscope images revealed the microstructure of scaffolds to be square shaped with continuous interconnected pores. The average pore size of the scaffolds was 265.70 + 67.45 μm. The scaffolds containing 8% (w/w) α-TCP exhibited the highest compressive modulus (64.84 + 16.65 kPa) and the highest calcium content. The results suggested that the scaffolds containing α-TCP may be a potential candidate for application in bone tissue engineering applications.

A novel method to fabricate porous tricalcium phosphate composite scaffolds for bone tissue engineering applications

This study reports a novel approach for the fabrication of three-dimensional scaffolds using tricalcium phosphate, carboxymethyl cellulose composite with alginate. Microporous (<20 μm) scaffold fibres were made by incorporating gas bubbles within fibres, stabilizing it with surfactants and subsequently removing the gas by vacuum treatment. The morphology of the scaffold was characterized using scanning electron microscopy (SEM). Further, for quantitative determination of pore size, the porosity distribution of the scaffold fibre was determined using mercury intrusion porosimetry (MIP). The volume porosity of these scaffolds was determined by liquid displacement method. Compressive strength, rigidity constant and stiffness index of the constructs were also determined. The in vitro bioactivity studies of these scaffolds were carried out in simulated body fluid (SBF) for 2/4 weeks. This study showed that the scaffold provides a favourable substrate conditions to form a bone-like mineral phase, which might play a significant role in osteointegration.

Controllable dual‐release of dexamethasone and bovine serum albumin from PLGA/β‐tricalcium phosphate composite scaffolds

Localized dual-drug delivery from biodegradable scaffolds is an important strategy in tissue engineering. In this study, porous poly(L-lactide-co-glycolide) (PLGA)/β-tricalcium phosphate scaffolds containing both dexamethasone (Dex) and bovine serum albumin (BSA) were prepared by incorporating Dex-loaded and BSA-loaded microspheres into the scaffolds. PLGA microspheres containing Dex or BSA were prepared by spray-drying and double emulsion/solvent evaporation, respectively. In vitro release studies indicated that microspheres prepared from PLGA in 3:1 molar ratio of L-lactide/glycolide and 89.5 kDa relative molecular mass showed prolonged release profiles compared with those prepared from PLGA in 1:1 L-lactide/glycolide molar ratio and 30.5 kDa relative molecular mass. Additionally, introduction of poly(ethylene glycol) in the PLGA chain could improve the encapsulation efficiency and reduce the release rate. Based on the above results, controllable dual-release of Dex and BSA with relatively higher or lower release rate was achieved by incorporating Dex-loaded and BSA-loaded microspheres with different release profiles into the PLGA/β-tricalcium phosphate scaffolds.

Fabrication of individual scaffolds based on a patient-specific alveolar bone defect model

Fabricating individualized tissue engineering scaffolds based on the three-dimensional shape of patient bone defects is required for the successful clinical application of bone tissue engineering. However, there are currently no reported studies of individualized bone tissue engineering scaffolds that truly reproduce a patient-specific bone defect. We fabricated individualized tissue engineering scaffolds based on alveolar bone defects. The individualized poly(lactide-co-glycolide) and tricalcium phosphate composite scaffolds were custom-made by acquiring the three-dimensional model through computed tomography, which was input into the computer-aided low-temperature deposition manufacturing system. The three-dimensional shape of the fabricated scaffold was identical to the patient-specific alveolar bone defects, with an average macropore diameter of 380 μm, micropore diameters ranging from 3 to 5 μm, and an average porosity of 87.4%. The mechanical properties of the scaffold were similar to adult cancellous bone. Scaffold biocompatibility was confirmed by attachment and proliferation of human bone marrow mesenchymal stem cells. Successful realization of individualized scaffold fabrication will enable clinical application of tissue-engineered bone at an early date.

Porous morphology, porosity, mechanical properties of poly(α‐hydroxy acid)–tricalcium phosphate composite scaffolds fabricated by low‐temperature deposition

Tissue engineering is expected to construct complicated hominine organs composed of many different types of cells. One of the key points is the accurate controlling of scaffold material and porous morphology point by point. A new direct rapid prototyping process called low-temperature deposition manufacturing (LDM) was proposed to fabricate scaffolds. The new process integrated extrusion/jetting and phase separation and therefore could fabricate scaffolds with hierarchical porous structures creating a wonderful environment for the growth of new tissue. The interconnected computer-designed macropores allow cells in the new tissue to grow throughout the scaffold. Also, the parameter-controlled micropores let nutrition in and metabolic wastes out. The macrocellular morphology, microcellular morphology, porosity, and mechanical properties of the poly(alpha-hydroxy acid)-TCP composite scaffolds prepared by the proposed method are investigated. These scaffolds with high controllability would potentially play an important role in tissue engineering. LDM could also be combined with multinozzle deposition or cell deposition to exactly control materials or cells point by point. This might bring a breakthrough to the engineered fabrication of complicated organs.

In vitro degradation of novel bioactive polycaprolactone—20% tricalcium phosphate composite scaffolds for bone engineering

Our group recently fabricated novel 3D polycaprolactone—20% tricalcium phosphate (PCL-TCP) composite scaffolds for applications in bone engineering. The bioactivity of such synthetic biomaterials can be evaluated by examining its ability to initiate the formation of apatite on its surface when immersed in simulated body fluids (SBF). In this study, the in vitro degradation behaviors of these scaffolds were systematically monitored for varying time periods of 1, 7, 14, 21 and 28 days post-immersion in SBF at 37 °C. Weight loss and water absorption of the samples indicated that PCL-TCP scaffolds were only slowly degraded. Biochemical assays and pH measurements revealed that hydroxyapatite, the main inorganic constituent of bone, commenced to form on the surface of the scaffolds after 17 days of immersion in SBF. Von Kossa assays demonstrated that calcium deposits increased progressively on the surface of the scaffolds after soaking in SBF for 2 weeks. Scanning electron microscopy verified the surface crystallization of the apatite layer formed over the entire period of time. In conclusion, the synergy of PCL with TCP in a composite scaffold confers both bioresorbability as well as bioactivity that offer an exciting approach for bone regeneration purposes.