| Summary: | The aim of this study is to understand what type of surface texture and chemistry after laser processing will have an effect on the biocompatibility of Ti-6AI-4 V. A number of laser techniques have been investigated to modify the surface properties including texturing, coating and heat treating. The biocompatibility of the samples was investigated by observing the apatite growth and monitoring osteoblasts (bone cell) attachment. Coating a 5 μm layer of Ca2Si04 by using a combined high power diode laser/sol-gel method on Ti-6Al-4V substrate resulted in increased cell attachment by 58% compared to the uncoated substrate. Laser oxide growth and micro-crack formation with minimized surface structuring was applied by Nd:YAG laser which resulted in increasing the formation of apatite (improved biocompatibility). Surface micro structuring was performed by using Nd:YAG, Excimer and Nd:YV04 lasers. The effect of structures with different sizes including micro-holes (larger than bone cell size), micro-grooves and micro-cones (in the range of bone cell size) on bone cell attachment is investigated. The effect of chemical modifications with and withouth structuring is also studied. Results indicated that laser processing improved the biocompatibility in all cases. Nd:YAG micro-texturing to produce micro-size holes (diameter-127 μm, centre to centre spacing-465 μm) with reduced chemical modifications, increased the osteoblast attachment on the substrate by 64% compared to the untreated surface. Producing micro-grooves and submicron ripples on Ti-6AI- 4V substrates by using a KrF excimer laser resulted in 20% increase in osteoblast attachment (50 μm groove width). Micro-cones and chemical modifications generated by Nd:YV04 laser resulted in the highest cell attachment (213%). This was repeated a number of times to provide statistical confidence of the results. The best results, for the first time, showed higher cell attachment than an untextured tissue culture plastic substrate. Immunoflorence microscopy indicated that osteoblasts created larger focal contacts on structures which showed highest cell attachment. This work was carried out in collaboration between the Laser Processing Research Centre (LPRC) of the Faculty of Engineering and Physical Sciences and the Faculty of Life Sciences, The University of Manchester.
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