Properties Of Composite Scaffolds Research Articles

Selected physico-chemical properties of composite scaffolds of sintered submicrocrystalline corundum and bioglass

Presented paper contains description and interpretation of the results of selected physicochemical and structural properties of two types of composite sinters. They were constituted of a mixture of sintered microcrystalline corundum and bioglass CaO-P2O5-SiO2-Na2O system intended for scaffolds to cell culture of human chondrocytes. The composites contained a mixture of both above-mentioned components in the volumetric proportion of 50:50 (W5) and 30:70 (W7). They were obtained using powder metallurgy by free sintering in air atmosphere. Phase analysis of composites and verification of theoretical identification using X-ray diffraction were performed. The same phases were found in both cases (Al2O3 SiO2 CaAl2Si2O8, Ca3 (PO4)2, Ca2Al4O7 and NaAlSiO4). Microscopic tests of composite surfaces were performed and some differences were found. W5 sample was not completely covered with bioglass, whilst W7 sample was completely covered with bioglass with few fine pores. Tests of surface topography confirmed the presence of large and small pores. Composite surfaces immersed for 30 days in artificial blood plasma were tested and then electron microscopy analysis was performed. It was found that no significant changes occurred on the surface of the W5 composite, probably partial corrosion of the glass happened. Spherical forms characteristic of HA-hydroxyapatites were observed on the surface of sample W7. Human articular chondrocyte cells were seeded on both types of sinters and proliferation assay was performed. Results indicate that tested scaffolds support cellular attachment and proliferation of chondrocytes.

Development of carboxymethylcellulose based composites for bone tissue engineering

The present study focuses on the development of carboxymethylcellulose (CMC)–biphasic calcium phosphate (BCP) composite scaffolds through the freeze-drying process for bone tissue engineering applications. Citric acid or fumaric acid was added as the cross-linker of CMC to improve the stability of composite scaffolds. The effect of change in freezing temperature (−20, −40 or −80°C) on the pore morphology, swelling ability and mechanical properties of composite scaffolds was studied. Cross-linked scaffolds showed an increased thermal degradation temperature compared with non-cross-linked scaffolds. All the composite scaffolds showed a porous structure with homogeneous blending of CMC and BCP. Cross-linked scaffolds showed appreciable swelling ability and stability in phosphate-buffered saline, while non-cross-linked scaffolds were unstable for 24 h. Cross-linked scaffolds had lower compressive strength than non-cross-linked scaffolds under dry conditions. However, in the hydrated state, only citric acid-cross-linked scaffolds were stable with improved compressive strength of 64 ± 4, 57 ± 4 and 67 ± 4 kPa when processed at −20, −40 and −80°C, respectively. Furthermore, three-dimensional culture of Saos-2 cells on citric acid-cross-linked scaffolds showed their suitability for cell proliferation and osteogenic differentiation. Therefore, citric acid-cross-linked CMC–BCP composite scaffolds may be promising scaffolds for bone tissue engineering applications.

Application of nanotechnology in the enhancement of elasticity of vital sign blood walls

To analyze the application of nanotechnology in the enhancement of the elastic strength of vital sign blood vessel walls, to study the effect of vascular endothelial growth factor (VEGF)-loaded multi-walled carbon nanotube (MWCNT) composite stents on blood vessels and to verify that nanotechnology can enhance the elastic strength of blood vessel walls. Through the purification of MWCNTs, the dispersion and stability of MWCNTs were improved, and functionalized MWCNTs were obtained. VEGF-loaded MWCNT composite scaffolds were constructed by using the infection method, and the mechanical properties of the composite scaffolds were tested. The higher the concentration of MWCNTs in the composite scaffold, the greater the maximum load and the stronger the ability of anti-elastic deformation. The 5% MWCNT composite scaffold had the best effect on promoting the growth of human umbilical vein endothelial cells. Compared with polycaprolactone scaffolds, MWCNT composite scaffolds had a more significant effect on promoting the proliferation of vascular cells and the endothelialization of blood vessels. The mechanical properties of MWCNT composite scaffolds are good, and they can increase endothelial cells and elastin. The application of MWCNT composite scaffolds in blood vessels can improve the elastic strength of blood vessels and provide reference for manufacturing better bone repair materials.

Biocompatibility properties of composite scaffolds based on 1,4-butanediamine modified poly(lactide-co-glycolide) and nanobioceramics

Three-dimensional biodegradable porous scaffolds play an important role in tissue engineering. The degradable scaffold material, based on 1,4-butanediamine-modified poly(lactide-co-glycolide) (BMPLGA), nano-bioactive glass (NBAG), and nano-β-tricalciumphosphate (β-TCP), was prepared by a solution-casting/salt-leaching method. The biological properties were studied by using cell cytotoxicity, von Kossa staining, alkaline phosphatase activity, hemolytic test, acute toxicity, and genetic toxicity test. The MTT results indicated that the BMPLGA/NBAG-β-TCP materials did not show any cytotoxicity. The result of von Kossa staining showed that the introduction of the NBAG and β-TCP promoted fibroblastic differentiation and improved the mineral deposition of the BMPLGA matrix. In addition, the presence of NBAG and β-TCP in the composite further enhanced the ALP activity in comparison with the sole BMPLGA material. The hemolytic potential showed that the nanocomposite scaffolds were non-hemolytic. The BMPLGA/NBAG-β-TCP scaffolds showed no acute systemic toxicity or mutagenic action. Therefore, the results indicated the BMPLGA/NBAG-β-TCP nanocomposite scaffold could be considered as a potential bone tissue engineering implant.

Influence of fish collagen on viscoelastic properties and sol-gel phase transition of chitosan solutions

The thermosensitive hydrogels are widely used in tissue engineering due to their non-invasive application. Special interest of researchers, due to the specific characteristics of both materials, is aimed at composites of natural origin obtained from chitosan hydrogels combined with collagen. The mechanical properties of the thermosensitive chitosan-fish collagen hydrogels and the sol-gel phase transition parameters were determined by the rotational rheometry measurement techniques. Based on comparison of the obtained storage modulus G' curves, it was found that the addition of collagen negatively affects the mechanical properties of composite scaffolds. The addition of this protein substance decreases their elasticity. Only the smallest concentration (0.25g collagen/1 g chitosan) of collagen improves the mechanical properties of composite hydrogels, from 56 kPa to 61 kPa. Conducted non-isothermal studies allowed to conclude that the addition of collagen causes an increasing temperature of sol-gel phase transition. However, the observed changes are not a monotone function of the biopolymer concentration.

A novel akermanite/poly (lactic-co-glycolic acid) porous composite scaffold fabricated via a solvent casting-particulate leaching method improved by solvent self-proliferating process.

Desirable scaffolds for tissue engineering should be biodegradable carriers to supply suitable microenvironments mimicked the extracellular matrices for desired cellular interactions and to provide supports for the formation of new tissues. In this work, a kind of slightly soluble bioactive ceramic akermanite (AKT) powders were aboratively selected and introduced in the PLGA matrix, a novel l-lactide modified AKT/poly (lactic-co-glycolic acid) (m-AKT/PLGA) composite scaffold was fabricated via a solvent casting-particulate leaching method improved by solvent self-proliferating process. The effects of m-AKT contents on properties of composite scaffolds and on MC3T3-E1 cellular behaviors in vitro have been primarily investigated. The fabricated scaffolds exhibited three-dimensional porous networks, in which homogenously distributed cavities in size of 300–400 μm were interconnected by some smaller holes in a size of 100–200 μm. Meanwhile, the mechanical structure of scaffolds was reinforced by the introduction of m-AKT. Moreover, alkaline ionic products released by m-AKT could neutralize the acidic degradation products of PLGA, and the apatite-mineralization ability of scaffolds could be largely improved. More valuably, significant promotions on adhesion, proliferation, and differentiation of MC3T3-E1 have been observed, which implied the calcium, magnesium and especially silidous ions released sustainably from composite scaffolds could regulate the behaviors of osteogenesis-related cells.

Calcium Phosphate-Loaded Strips, Plugs and Putties: Physico-Chemical Properties for Osteopromotion and Ease of Surgery

The present study focuses on the physico-chemical and structural properties of composite scaffolds composed of biopolymer matrices (collagen or polysaccharide) loaded with calcium phosphate granules. A systematic three-dimensional analysis method was used to quantitatively characterize a series of plugs, strips and putties in terms of percentage of inorganic filler particles, size of the loaded granules, and spatial homogeneity of the calcium phosphate granules distribution. It appears clearly that each biomaterial currently available on the market offers specific properties. As a consequence, surgeons have to choose the medical device that best suits their needs depending on the clinical constraints but also should be aware of the mineral properties which remains key to bone reconstruction.

Structural and Mechanical Properties of Composite Scaffolds Based on Nano-hydroxyapatite and Polyurethane of Alcoholized Castor Oil

The interfacial interaction between two phases and homogeneous dispersion of inorganic phase in the organic matrix are critical factors for composite scaffolds with good structure and properties. Based on the modified soft-segment (alcoholized castor oil, ACO) of polyurethane (PU) and nano-hydroxyapatite (n-HA), porous n-HA/PU composite scaffolds were fabricated with in situ foaming method by controlling the process technology in this study. The results demonstrate that there exists good interfacial interaction between PU polymer matrix and polar n-HA due to increased hydroxyl number of modified polyurethane. Moreover, the n-HA filler can homogene- ously disperse among the matrix and the miscibility is also dramatically improved. The micropore size of scaffolds is uniform, while the porosity, pore sizes and crystallinity are slightly decreased. FTIR and XRD analyses reveal that there are a large amount of hydrogen bond and chemical linkages between n-HA and ACO-PU matrix, which enhance the miscibility and stability of organic and inorganic phases. Correspondingly, the compressive strength and compressive modulus of scaffolds are significantly improved by alcoholized polyurethane and the uniformly dispersed n-HA particles. The nanocomposite scaffold can be used for further researches on regenerative medicine and bone tissue engineering.

Composite Scaffolds Based on Poly(caprolactone) and Chitosan for Bone Tissue Regeneration

The scaffold material and architecture of the scaffold can affect cell seeding and tissue growth both in vitro and in vivo in the engineering of various tissues. Biocompatible and biodegradable polymers can be used to produce scaffolds in tissue engineering. Poly(caprolactone) PCL and Chitosan are promising biodegradable polymers to fabricate tissue engineering scaffolds. Hydroxyapatite (HA) is osetoconductive and is being used for bone replacement. The composite scaffolds made of these two materials have great potential for bone tissue engineering. This paper reports the fabrication and characterization of three-dimensional, highly porous composite scaffolds produced from HA/PCL and HA/Chitosan. The scaffolds were produced using thermally induced phase separation (TIPS) technique. The structure and properties of composite scaffolds were investigated using various techniques.

Electrospun poly (lactic-co-glycolic acid)/ multiwalled carbon nanotubes composite scaffolds for guided bone tissue regeneration

A series of poly (lactic-co-glycolic acid) (PLGA)/multiwalled carbon nanotubes (MWNTs) composite scaffolds was prepared by electrospinning for tissue engineering applications. The effect of MWNTs content on the structure and properties of composite scaffolds was characterized by scanning electron microscopy (SEM), X-ray diffractrometry (XRD), thermogravimetric analysis (TGA), and universal testing machine (UTM). The attachment ability and viability of rat bone marrow-derived mesenchymal stem cells (BMSCs) in the presence of the scaffolds were also investigated. Morphological characterization showed that the addition of different amounts of MWNTs increased the average fiber diameter; for instance, from 717 nm (neat PLGA) to 2193 nm at 1.0% MWNTs. Thermal characterization showed that the incorporation of MWNTs into the PLGA matrix increased the thermal stability of the composite scaffolds. The analysis of mechanical properties of the PLGA/MWNTs composites revealed great improvement over pure PLGA scaffold. The attachment and proliferation of BMSCs were significantly increased in the PLGA/MWNTs scaffolds compared with the PLGA control. Therefore, the PLGA/MWNTs composite scaffolds fabricated by electrospinning may be potentially useful in tissue engineering applications, particularly as scaffolds for bone tissue regeneration.

Fabrication and Characterisation of Polymer and Composite Scaffolds Based on Polyhydroxybutyrate and Polyhydroxybutyrate-Co-Hydroxyvalerate

This paper reports the fabrication and characterization of three-dimensional, highly porous polyhydroxybutyrate (PHB), polyhydroxybutyrate-co-valerate (PHBV) and composite scaffolds made by the emulsion freezing / freezing-drying technique. Freeze-drying of the polymer/solvent/ water phase emulsions produced hard and tough scaffolds with interconnected pores. The effects of the fabrication parameters such as polymer concentration in emulsions and emulsion stabilizer were examined and optimized. The density of polymer scaffolds was found to increase with an increasing polymer concentration. Structural analyses of selected samples using scanning electron microscopy indicated that the scaffolds had pore sizes ranging from several microns to a few hundred microns. The porosity of scaffolds of up to 85% was achieved and it increased with a decreasing polymer concentration. It was found that mechanical properties of composite scaffolds increased with the increasing amount of hydroxyapatite (HA) incorporated in the scaffolds.