Introduction: Titanium implants can be regarded as the current gold standard for restoration of sound transmission in the middle ear following destruction of the ossicular chain by chronic inflammation. Many efforts have been made to improve prosthesis design, while less attention had been given to the role of the interface. We present a study on chemical nanocoating on microstructured titanium contact surface with bioactive protein.
Materials and Methods: Titanium samples of 5mm diameter and 0,25mm thickness were structured by means of a Ti:Sapphire femtosecond laser operating at 970nm with parallel lines of 5μm depth, 5μm width and 10μm inter-groove distance. In addition, various nanolayers were applied to titanium samples by aminosilanization, to which Star-Polyethylene glycole (Star-PEG) molecules plus biomarkers (e.g. RGD peptide sequence) were linked.
Results: Chondrocytes could be cultured on microstructured surfaces without reduced rate of vital / dead cells compared to native surfaces. Chondrocytes also showed contact guidance by growing along ridges particularly on 5μm lines. On nanocoated titanium samples, first results showed a strong effect of Star-PEG suppressing unspecific protein absorption, while RGD peptide sequence did not promote chondrocyte cell growth.
Discussion: According to these results, the idea of promoting cell growth on titanium prosthesis contact surfaces compared to non-contact surfaces (e.g. prosthesis shaft) by nanocoating is practicable. However, relative selectivity induced by microstructures for growth of chondrocytes compared to fibrocytes is subject to further evaluation.
The objective of this study was to optimize titanium surfaces by means of Ti:Sapphire femtosecond laser to improve the
attachment of human cartilage cells on titanium prosthesis in middle ear surgery. The application of microstructures on
titanium samples was evaluated and the influence of these microstructures on human auricular chondrocytes was studied
in-vitro. After establishing the ear chondrocyte cell culture, cells were seeded on titanium platelets with selected
microstructure patterns. Whereas the phenotype of cells seeded on unstructured titanium was similar to cells grown on
standard tissue culture surfaces, the morphology of chondrocytes grown on structured titanium samples was influenced
by the pattern. For future titanium middle ear prosthesis structural optimizations will be developed to promote
chondrocyte growth and adhesion while impeding fibrocyte proliferation to avoid scarring on implant interfaces.
Introduction: While a variety of materials has been evaluated for replacement of human middle ear ossicles following inflammation, titanium and its alloys have shown excellent sound transmission properties and biocompatibility. However, cartilage thickness at the tympanic membrane interface deteriorates over time, while fibrous tissue formation may dislodge the titanium prosthesis. This study was performed to evaluate the effect of microstructures on titanium surfaces in contact with adjacent biological tissue.
Materials and Methods: Titanium samples of 5mm diameter and 0,25mm thickness were structured by means of a Ti:Sapphire femtosecond laser operating at 970nm. The structures applied were lines of parabolic shape (cross-sectional) of 5µm (parallel), 5µm (cross-hatch) and 10µm width (parallel). The inter-groove distance between two maxima was exactly twice the line width.
Results: Lines smaller than 5µm were not feasible due to the natural irregularity of the basic material with pits and level changes of up to 2µm. The process showed little debris and constant microstructure shape over the whole structured area (2x2mm). The resulting debris was examined for toxic by-products on human fibrobcytes and chondrocytes.
Discussion: The results show that microstructures can be applied on titanium surfaces for human implantation with reproducible and constant shapes. Further studies will focus on cell culture which has suggested a relative selectivity for chondrocyte compared to fibrocyte growth in earlier studies with selected microstructures.
Since operation microscopes have been introduced to otology in the early 1950's, surgical reconstruction of
middle ear function has been developed further to restore sound transmission with lowest loss possible. Today, research
focuses on material properties for prosthetic replacement of middle ear ossicles and long-term outcome of reconstructive
middle ear surgery. This study shows how stereoscopy is used to evaluate tissue-material interaction and its clinical
impact for future restoration of middle ear function.
Conventional lithography is a leading high-throughput patterning method for mass production. But the dramatically increasing cost of lithographic equipment and mask sets, which is a consequence of pushing optical lithography to its limits, makes alternative, maskless lithographic techniques attractive. Femtosecond lasers have been found suitable for processing of a wide range of materials with sub-micrometer resolution. The limit of achievable structure sizes is predicted to be below 100 nm. Therefore, it is attractive to use this technique for maskless lithography. In this paper, first results on super-resolution femtosecond laser lithography showing great potential for future applications are presented.
Rapid progress in ultrafast laser systems opened many exciting possibilities for high-resolution material processing. These laser systems allow to control and deliver optical energy and laser pulses in time and space with unprecedented precision. It is not surprising that these high-quality optical pulses have revolutionized microfabrication technologies. Femtosecond lasers enabled processing of a wide range of materials (including heat sensitive and thermo reactive) with a sub-micrometer resolution. At present, nearly arbitrary shaped 2D and 3D structures can be produced by direct write photofabrication techniques using femtosecond laser pulses. In this paper we present a brief review of our recent progress in femtosecond (maskless, direct-write, nonlinear) laser lithography and 3D photofabrication technique.
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