Papers by Keyword: Biomaterial

Abstract: Waste materials can have negative environmental impact and cost implications associated with their safe disposal given the increasing awareness and stringent environmental standards. Several options for utilization of waste have been explored in the lab scale and pilot scale. In this article high value materials obtained from waste are reviewed. This includes industrial waste, food industry waste and combustion residues, to obtain transition metal based catalysts, biomaterials and zeolites respectively. The different approaches to the processing and the properties of the product are discussed.

Abstract: The paper discusses the possibility of manufacturing dental implants through Selective Laser Melting (SLM) of a Ti-6Al-4V alloy powder. Among all possible biomaterials, this alloy is widely used in biomedical applications due to high biocompatibility. Selective Laser Melting allows to obtain biomaterials with peculiar characteristics in terms of porosity gradient, roughness, customized geometry, and mechanical properties. Influence of input process parameters on porosity and analysis of Selective Laser Melting capabilities in implant dentistry have been focused. Porosity is a key parameter in dental implants as it affects stiffness, which is related to Young’s modulus. Ti-6Al-4V bulk material presents a Young’s modulus of 110 GPa, whereas the bone one ranges from 10 to 26 GPa. The relative difference of mechanical properties causes the phenomenon of stress shielding, which has a detrimental effect on the longevity of dental implants. Total porosity is important in reducing the effective modulus of porous metals. Biomaterials specimens obtained during experimental phase have been examined in terms of porosity (in inverse ratio to relative density), microstructure, microhardness and roughness. According to test results discussed in this paper, Selective Laser Melting is proved to be an efficient technology for the construction of Ti-6Al-4V dental implants, because biomaterials with adequate properties can be obtained changing processing parameters. Other fabrication techniques fail to produce biomaterials for dental implants with the desired features.

Abstract: Titanium and titanium alloys scaffolds have been widely explored in many load-bearing orthopaedic applications due to their excellent strength and corrosion resistance. However, their biocompatibility is also an important concern in these applications due to adverse reactions of metallic ions with the surrounding tissues after these metallic ions are released from implant surfaces. To respond on the challenge of producing a biocompatible material, a review on structural properties and surface treatments on titanium scaffolds and their effects on biological responses (in vitro and in vivo) are briefly presented.

Abstract: Titanium and titanium alloys have been widely employed in many load-bearing orthopaedic applications due to their excellent strength and corrosion resistance. However, postimplantation infections might occur even though considerable studies have been made. Choosing a bio-friendly alloying element is one way to reduce infection risk. The aim of this study is to evaluate the extent of bacterial attachment on titanium, tantalum, niobium and tin surfaces. Two pathogenic bacterial strains, namely Staphylococcus aureus CIP 65.8T and Pseudomonas aeruginosa ATCC 9027, were used in this study. Quantification of bacterial attachment was performed using scanning electron microscopy. Results indicated that the surface chemistry and topography of the investigated materials significantly influence the degree of P. aeruginosa and S. aureus adhesion; however, surface wettability did not show a significant impact upon bacterial retention. In this study, tin was shown to be the most attractive material for bacteria adhesion but tantalum limits the bacterial adhesion. Therefore, it is suggested to limit the amount of tin as an titanium alloying element due to its nature to attract P. aeruginosa and S. aureus adhesion.

Abstract: Ti-6Al-7Nb titanium alloy is attractive to medical device industry for orthopedic applications, such as total hip replacement systems, fracture fixation plates, intermedullary rods and nails, spinal devices, screws, and wires. Substituting Niobium for Vanadium as the beta stabilizing element, Ti-6Al-7Nb titanium alloy shows higher biocompatability than Ti-6Al-4V titanium alloy. The present research is designed to investigate the influence of annealling temper on the mechanical properties and microstructures of Ti-6Al-7Nb titanium alloy, by optical microscopic (OM) and scanning electron microscopic (SEM), and tensile test. The results show that the microstructures after recrystalization heat treatment comprise a mount of equiaxed α grains in the matrix of equiaxed β phase with α (hcp)/ β (bcc) platelets. The microstructures with partial recrystalization α phase possess better mechanical properties which conform to the ASTM F 1295 standard and ISO 5832-11 standard. Compared with Ti-6Al-4V titanium alloy and CP titanium alloy, Ti-6Al-7Nb titanium alloy is suitable to be used as implanted biomaterial devices to replace ill-functioning or missing tissues or organs.

Abstract: With the goal to develop biocompatible material collagen extracted from tilapia scale as coating material to encapsulate bioactive compounds, a microsphere containing L-ascorbic acid as a model is developed, using natural nontoxic transglutaminase (TG) as cross-linking agent. Ultrasonic wave was applied in the process to assist preparing microcapsule. Factors of emulsifier, TG, ratio of L-ascorbic acid and collagen, incubation temperature were discussed. The formulation from orthogonal experiment was of the optimal encapsulation efficiency 81.17%.It is found that the collagen extracted from tilapia scale is a potential biomaterial.

Abstract: Aim of the study is to investigate the in vitro reaction between rat bone cell and poly (vinyl alcohol) (PVA)-matrix composites. Sample of Hydroxyapatite (HA) /PVA gel composites were prepared by the in situ growth method and Experiments of Alamar Blue Activity and Alkaline Phosphatase Assay were carefully made in our lab. SEM results displays that PVA-matrix composites containing HA fillers and pure PVA as a control group have an excellent biocompatible bone reaction in vitro with rat bone cells and HA filler particles in composites promote reaction between bone cell and composites. In vitro biology experiment resulted proves that adhesion, growth and differentiation of bone cells on all PVA-matrix composites are promoted by HA filler particles.

Abstract: The magnesium alloys has been intensively studied for their suitable mechanical properties, excellent biocompatibility and their ability to biodegrade in biological environments. Although magnesium biodegradable implants possess many desirable properties, it is important that the alloy is able to be tolerated by the body- the constitutional elements of magnesium-based alloys should be toxic free. In this study two binary magnesium alloys Mg-Ca0,8 and Mg-Ca1,8 were experimentally obtained by casting and was characterized in order to investigate the microstructure, mechanical properties and how alloying elements influenced the characteristics of this new alloys potentially used for orthopedic implants.

Abstract: This paper presents a comparative bibliographic study of different materials with elevated biomechanical biocompatibility regarding the stent-blood vessel interaction. Only the materials used in coronary stents’ manufacturing are considered: stainless-steel (316L), Cobalt-Chromium alloys (CoCrMo, CoNiCrMo), Nickel-Titanium alloys (Nitinol), Tantalum. The main characteristics that result from the stress-strain curve of each material are presented, as well as the biocompatibility and durability. The stainless-steel has good mechanical properties, excellent biocompatibility and low price. Cobalt-Chromium alloys have excellent mechanical properties, excellent biocompatibility, acceptable shape memory properties, but high density and low flexibility. The Nitinol represents the best choice, with excellent mechanical properties, excellent biocompatibility, good corrosion resistance, high flexibility (super-elastic behavior), low density, but high price. Tantalum alloys present the best biocompatibility and high flexibility, but the mechanical properties are relative modest.

Abstract: In the past years an increased interest to create new polymeric blends with application in the medical area for development of new types of biomaterials has appeared. Electron beam irradiation is well known as a method of producing important changes in polymer structure, being an alternative to chemical synthesis of biomaterials based on polymeric materials. The aim of the present study was to investigate the behaviour of some polyvinylpyrrolidone-dextran (PVP/DEX) blends under electron beam irradiation. Aqueous solutions of PVP with molecular weights of 360 000 Da (PVP 360), 40 000 Da (PVP 40), and DEX with molecular weight of 500 000 Da (DEX), were mixed as to obtain 50:50 blends of PVP40/DEX and PVP360/DEX. The obtained blends were irradiated with electron beam at different radiation doses and after irradiation treatment were processed by freeze-drying. PVP/DEX blends were characterized by infrared spectroscopy (FT-IR) and thermal analysis. The analyses were conducted in order to establish the relation between radiation dose and changes of structural and thermal properties.