It is well-known that nanoparticles could cause toxic effects in cells. Alloy nanoparticles with yet unknown health risk may be released from cardiovascular implants made of Nickel–Titanium or Cobalt–Chromium due to abrasion or production failure. We show the bio-response of human primary endothelial and smooth muscle cells exposed to different concentrations of metal and alloy nanoparticles. Nanoparticles having primary particle sizes in the range of 5–250 nm were generated using laser ablation in three different solutions avoiding artificial chemical additives, and giving access to formulations containing nanoparticles only stabilized by biological ligands. Endothelial cells are found to be more sensitive to nanoparticle exposure than smooth muscle cells. Cobalt and Nickel nanoparticles caused the highest cytotoxicity. In contrast, Titanium, Nickel–Iron, and Nickel–Titanium nanoparticles had almost no influence on cells below a nanoparticle concentration of 10 μM. Nanoparticles in cysteine dissolved almost completely, whereas less ions are released when nanoparticles were stabilized in water or citrate solution. Nanoparticles stabilized by cysteine caused less inhibitory effects on cells suggesting cysteine to form metal complexes with bioactive ions in media.
Top down technique of interfering femtosecond laser processing was applied to generate new nanomaterials such as nanocrown, nanomesh, nanobelt, and dual periodic structure. In the case of nanocrown, whiskers are standing at the edge of a nanohole. The width of a whisker was just 80 nm. A nanohole array structure generated by interfering 4 beams was applied to a spatial filter as a base material for the growth of photo-polymerizing polymer, and polymer nanobump array was generated. Dual periodic structures were generated by multiple shots, and bimetallic nanobelt was generated from bilayer thin film. Processing of fiber film was tested.
A cochlear implant (CI)-associated local drug delivery system based on dexamethasone (DMS) was developed with the purpose to inhibit the growth of fibrotic tissue which influences the signal transmission from the CI to the neurons of the inner ear. For the realization of a targeted DMS delivery the following concepts were combined: modification of the silicone-based electrode carrier by incorporation of DMS and a DMS-containing polymeric coating chemically attached on the surface of the electrode carrier. It was demonstrated that the coated CI showed a high coating stability in a simulated implantation procedure. The in vitro drug release studies in a quasi-stationary model revealed a faster DMS release in the initial phase originating from the DMS-containing coatings and then a lower and sustained DMS release originating from the DMS-loaded silicone carrier. The performed in vitro biocompatibility study confirmed that the released DMS was non-toxic for cultured spiral ganglion cells.
An overview of the vast array of the laser material processing techniques is presented as they apply to fabricating structures in the micro and nanometer scale length domains. The overview covers developments from the past 20 years, and encompasses demonstrated processes where the use of the inherent properties of lasers has led to increased fidelity in the processing of materials. These demonstrated processes often use inventive approaches that rely on derivative aspects of established primary principals that govern laser/material interaction phenomena. By using these nuances in concert with the unique properties of lasers, a high level of finesse has been demonstrated in materials processing. The overview highlights by the use of selective examples those processes or techniques that appear to show scalability to the industrial environment.Keywords: laser processing, overview, micro/nanofabrication, IntroductionLasers have been used in materials processing for over 50 years, though in the early days, work was more focused on mitigating laser damage in materials as opposed to the processing of materials. However, the application of lasers to controllably alter materials was recognized early and as an industry, laser processing applications now lead world wide laser sales. The calendar 2005 totals for laser process tooling is near $6.0B USD 1 . Consequently, laser materials processing can no longer be considered a niche industry as there appears to be an increasing demand to apply laser processing solutions to manufacturing for specific value added segments. Commensurate with these industry trends is the fact that the number of conferences devoted to laser material processing continues to grow. This is a normative signal that industry is currently more amenable to applying laser based solutions into the manufacturing process. There are many factors that have contributed to this change in view over the course of the past 2 decades, the primary one being the advance of laser technology with a commensurate increase in system reliability. Figure 1 shows a graph that depicts the number of world wide publications per year that mention laser material processing in the title or the abstract. The data spans nearly 40 years. The results represent a lower value to the total number of publications because there could be publications that discuss laser material processing research or development but fail to mention it in the title or abstract. The data is from an assembled series of databases that includes not only journal articles but also government sponsored research articles from the USA, Japan (e.g. MITI), Germany (e.g. BMFT), France (e.g. CNRS), Canada (e.g. NRC), UK (e.g. Department of Industry) and others. This data supports the conclusion that laser material processing is an established field that could support nearly 400 publications per year.In this paper we explore a small segment of the overall laser material processing industry, namely the use and application of lasers in micro and nanofabrication. By their ver...
Polymeric nanomaterials are gaining increased interest in medical applications due to the sustained release of bioactive agents. Within this study nanomaterials are fabricated using laser ablation of silver and copper in polymer‐doped organic liquids thus allowing to produce customized drug release systems. A strategy is shown to determine the therapeutic window for cells relevant for cochlear implant electrodes, defined by the viability of L929 fibroblasts, PC12 neuronal cells, and spiral ganglion cells on different concentrations of silver and copper ions. The distribution of nanoparticles within the silicone polymer matrix is determined using transmission electron microscopy. Hexane doped with 1% silicone resin is found to be an appropriate liquid matrix to fabricate a nanocomposite with a constant ion release rate. Silver ions of 10 µmol L−1 or copper ions of 100 µmol L−1 cause a suppression of tissue growth without inhibiting neuronal cell growth. The copper nanoparticle content of 0.1 wt% of the silicone composite releases ion concentrations which fit the therapeutic window.
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