Papers by Keyword: In Vitro Test

Abstract: In this study, the effects of curing white Portland cement (WPC) and hydroxyapatite mixed with white Portland cement (HAp/WPC) pastes in water and the in vitro biological environment on the compressive strength and bone-like apatite formation were examined. The compressive strength of both WPC and HAp/WPC pastes increased with longer curing periods in water. The compressive strength of WPC and HAp/WPC pastes was 51.88 and 25.67 MPa, respectively, after curing in water for 28 days. The compressive strength of both samples continuously increased during in vitro testing in a simulated body fluid (SBF). After 4 weeks of immersion in a SBF, the strengths of cured WPC and HAp/WPC samples were 59.01 and 28.06 MPa, respectively. It is due to continued hydration of WPC. The addition of HAp to WPC decreased the compressive strength of the sample. Alternatively, it enhanced bone-like apatite formation on the surface of the samples.

Abstract: Additive Manufacturing (AM) - is a technology that fabricates the parts directly from 3D CAD model without the need of any process planning. The convergence of AM and life science has evolved into a new paradigm called Bio-Additive Manufacturing (BAM). In this paper, Hydroxyapatite (HA) powder was coated over the customized implant, which will serve as a good candidate for bone substitutes due to its chemical and structural similarity to bone. Computer Tomography (CT) scan data of human tibia bone was collected and stacked in MIMICS image processing software, which converts it into 3D data, then implant was fabricated using Selective Laser Sintering (SLS), an AM technique with polyamide powder. Hydroxyapatite powder was synthesized by wet chemical process and coated over implant using plasma spray coating machine. This coating will produce an intermediate region between the bone and the implant, which will stimulate the tissue growth and bone contact. Micrograph of coated and uncoated implant was analyzed using SEM and EDX. For In-Vitro study human mesenchymal cell was cultured over the coated implant. The viability and proliferation of the cells was studied by examining the morphology of the cell. Thus the implant was fabricated using SLS technique and coated with hydroxyapatite powder which exhibits a favorable and good response to enhance tissue growth.

Abstract: In this work prototypes of internal fixation plates of acetabular fractures were developed and manufactured. The injection moulding was used to produce polymeric and composite samples. The plates and paddle-like beam samples made of polylactide and the polymer composite modified with 7 wt. % of tricalcium phosphate were produced. The samples were incubated in physiological fluids for 8 months. During the in vitro tests their durability and mechanical properties were determined. In comparison to the pure polylactide the addition of TCP accelerated degradation process. The degradation of the composite started after about 100 days of incubation, whereas the initial polymer began to degrade about 50 days later. The obtained biodegradable plates revealed sufficient mechanical properties for internal fixation of acetabular fractures for bone joining.

Abstract: Carbon-based nanocomposite thin films have large application potential because they possess unique mechanical properties, especially high hardness, high elasticity, and a low widely adjustable friction coefficient. In this work, relatively easy preparation of the nanocomposite Ti and C system with good mechanical properties and bioactivity was showed. Formation of physical and mechanical processes, relationship between the evolving structure and other properties of TiC films were studied. The films were deposited on oxidized silicon substrates by dc magnetron sputtering of Ti and C targets in argon and nitrogen at different temperatures between 25°C and 800°C. The composite films consisted of metallic nanocrystalls embedded in a carbon matrix. Highest hardness ~ 18 GPa and reduced modulus of elasticity ~ 205 GPa were obtained when the crystalline nanoparticles were separated by 2-3 nm thin carbon matrix consisting of amorphous and graphite-like carbon phases. In these films the H/E ratio in the both cases is ~ 0,1. Bioactivity studies were carried out on human osteoblast-like cell line MG-63. The number of initially adhering cells on day 7 after seeding was significantly higher on the TiC surface than on the control culture dishes. Good biocompatibility and bioadhesion of these surfaces are attained by a favourable combination of surface roughness and chemistry.

Abstract: Nano-hydroxyapatite (n-HA)/chitosan (CS)/konjac glucomannan (KGM) composite was prepared by integrating composition and molding. Then, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the physical, chemical and degradable properties of the composite before and after in simulated body fluid (SBF). Moreover, study in vitro test for drug delivery revealed that the amount of released pentoxifylline (1-[5-oxohexyl]-3,7-dimethylxanthine)(PTX) reached a plateau and equaled 80% of the drug loaded in an implant. The newly develop n-HA/CS/KGM composite may serve as a good degradable biomaterial for implantable drug delivery system (IDDS) in bone tissue engineering.

Abstract: Dense and porous HA and Si-HA discs and granules with varying percentages of silicon substitution have been produced and physically and chemically characterised using scanning electron microscopy, surface area analysis, porosimetry, density measurement, image analysis, Xray diffraction, X-ray fluorescence, FT-infrared spectroscopy and in-vitro and in-vivo testing. Results have shown that cell adhesion in-vitro and bone apposition in-vivo are enhanced by the presence of silicon substitution in the hydroxyapatite structure. The biological response to the materials appears to indicate an optimum outcome for levels of silicon substitution of 0.8wt%.

Abstract: Two different Ti oxide films produced by anodic oxidation were submitted to in vitro bioactivity and cell culture tests. The oxide films were produced in 1.0M H2SO4/150V and 1.0M Na2SO4/100V. Surfaces were found to be homogeneous and rough, with the presence of pores. Both oxide films presented anatase and rutile phases. Ti oxide film produced in Na2SO4 was rougher than the film grown with H2SO4 and composed of a rutile-rich phase. Both films were constituted by TiO2 and Ti2O3 oxides. Despite the differences observed, after 7 days, a calcium phosphate layer was precipitated on both surfaces. Indeed, these two treatment conditions seem to be efficient to spread and attach osteoblast-like cells within 4h.

Abstract: Despite systemic prophylaxis, infection rates after orthopedic surgery can reach more than 1%. A new HAP/TCP bone substitute loaded with 125 mg of gentamicin was designed for prophylactic use. Its aim was to enhance the efficacy of systemic prophylactic treatments by increasing the local antibiotic concentration. For prophylactic applications, release had to take place within 48 hours not to select antibiotic-resistant bacterial strains. The purpose of this study was to investigate the releasing mechanisms of gentamicin from the porous HAP/TCP matrix. The release rate of gentamicin trough the porosities of the bone substitute was investigated in vitro, in 0.9% sodium chloride solution. The rate appeared to be related to the bone substitute volume and fit classical diffusion laws. All the gentamicin was released in less than 48 hours: this rate corresponds to the recommendations for the prophylactic use of antibiotics.

Abstract: Wollastonite bioceramics prepared from synthetic and natural precursors were implanted in rats in bone and subcutaneous tissues. The implant sites were excised after 7, 30 and 120 days, fixed, dehydrated, embedded in paraffin wax for serial cutting and examined under transmitted light microscope. It was found a very similar behavior for both wollastonite bioceramics. They were biocompatible, bioactive and biodegradable when implanted in rat bone. The synthetic ceramic was more reabsorbable than the one from natural powder. When implanted in subcutaneous rat tissue, both materials elicited a mild initial inflammatory reaction that practically disappeared after 120 days. Both materials were encapsulated with a very thin fibrous capsule and slightly reabsorbed at their surfaces. None of the materials induced ectopic osteogenesis. According to the results, the studied materials seem to be able for manufacturing reabsorbable bone implants.