Browsing Department of Mechanical Engineering & the Built Environment by Subjects
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Antibacterial coating made of strongly adhered nanosilver to titania nanotubes for dental implantsObjectives: An antibacterial and biocompatible coating on Ti-6Al-4V alloy was synthesised. A method of making the antibacterial effect long term, without any acute release of silver from a dental implant, on insertion was devised.Methods: Titania nanotubes were grown on Ti-6Al-4V alloy using anodisation in the presence of phosphate and fluoride ions. Following alkali treatment of the latter surface, silver nanoparticles were chemically reduced on the nanotubes. The latter surface was then characterised using high resolution electron microscopy (SEM) in association with energy dispersive X-Ray Spectroscopy (EDS) and Raman Spectroscopy. A silver release test was performed. Following a toxicity test in the presence of Human Osteoblast Cells, the biocompatibility of the coating would be assessed.Results: Initially, titania nanotubes with diameter of c. 100 nm were formed following the deposition of silver nanoparticles (10-25nm) on the outer and inner walls. The chemical structure of the nanoparticles was confirmed by Raman Spectroscopy and EDS. The results also highlighted the different bonding attaching the nanosilver to the walls. Subsequently a very low amount of silver was released from the coating during the beginning of the silver release test confirming a good adherence between the nanosilver and the nanotubes. The low leaching was expected to reduce the toxicity of the implant in general and it was confirmed by growth of human osteoblast cells on the coating.Conclusions: The strong adhesion of silver nanoparticles validated the fact that the coating on titanium alloy can prevent an acute release of silver as such having the possibility of having a long term antibacterial effects. This work gave rise to a novel method of synthesising an antibacterial coating for dental implants.
Hydroxyapatite/Carbon nanotubes composite bone implants - Biocompatibility Vs Toxicity AnalysisPoor wear resistance and low fracture toughness are the main disadvantages of using hydroxyapatite (HA) for orthopaedic implants. This can be overcome by the use of Carbon nanotubes (CNTs) as reinforcements due to their versatile properties e.g. high stiffness and mechanical strength.The main aim of this study is to develop HA composite reinforced with CNTs and to investigate their biocompatibility.Methods: HA in the presence of CNTs was synthesised following a sol-gel technique. Six different types of powders were produced by altering two variables – functionalization and presence of surfactants. The composites were produced by mixing Hydroxyapatite /carbon nanotube powder with Polyvinyl alcohol (PVA) in equal proportions. Primary Human Osteoblast cells were used for the biocompatibility study. LDH, ALP, pH and Ion content analyses were performed on external media every 24 h for 3 days and at the end of the study LDH, ALP and protein assays were performed using cell homogenate to measure various cell activities. SEM analysis was also performed.Results: A drop in pH was observed after 24 h which recovered to neutral pH by the end of day 3. Total protein content was confirmed on all materials. Cell survival was analysed by performing LDH assay on cell homogenate at the end of day 3. ALP assay was performed to determine the mineralization activity of the cells. Finally, the material was qualitatively analysed under SEM and the presence of cell material was observed.Conclusions: CNTs possess properties that are highly desirable in the development of biomaterials. However, there has been controversy regarding their biocompatibility and cytotoxicity. This study explores the biocompatibility of HA /CNTs composite as bone implants. The results show that CNTs are biocompatible and can be employed in the development of bone implants.