Switchable adhesion principle enables damage-free handling of sensitive devices even in vacuum

Components with highly sensitive surfaces are used in automotive, semiconductor and display technologies as well as for complex optical lens systems. During the production, these parts often have to be handled many times by pick-and-place processes. Each pick-up and release with conventional gripping systems involves the risk of either contamination of the surfaces with residues from transportation adhesives, or damage due to mechanical gripping. Suction cup systems diminish residues, but fail in a vacuum or on rough surfaces. Researchers at the Leibniz Institute for New Materials (INM) have now enhanced the Gecko adhesion principle such that adhesion can be switched on and off in vacuum. The researchers from the INM will be presenting their results from 13 to 17 April 2015 in Hall 2 at the stand B46 of the Hannover Messe in the context of the leading trade fair for R & D and Technology Transfer. Switchable adhesion principle enables damage-free handling of sensitive devices even in vacuum Switchable adhesion principle enables damage-free handling of sensitive devices even in vacuum; (Image: Uwe Bellhäuser) "Artificially produced microscopic pillars, so-called gecko structures, adhere to various items. By manipulating these pillars, the adhesion can be switched on and off. Thus, items can be lifted and released quickly and precisely," Karsten Moh from the Program Division Functional Microstructures explains. "This technique is particularly interesting in vacuum, as suction cups fail there," says Moh. With the currently developed adhesion system, adhesive forces of more than 1 Newton per square centimeter can be achieved on smooth surfaces." In our tests, the system has proved successful even after 100,000 cycles", the upscaling expert Moh says. Even slightly rough surfaces can be handled reliably. The developers now focus on increasing the adhesion force to lift and release large components and heavy materials in an energy-efficient way. Furthermore the development group works on the gripping of objects with curved surfaces without leaving residues. Additionally, the scientists also focus on developing other triggers for switching the adhesion like light, magnetic field, electric field or changes in temperature. INM conducts research and development to create new materials – for today, tomorrow and beyond. Chemists, physicists, biologists, materials scientists and engineers team up to focus on these essential questions: Which material properties are new, how can they be investigated and how can they be tailored for industrial applications in the future? Four research thrusts determine the current developments at INM: New materials for energy application, new concepts for medical surfaces, new surface materials for tribological applications and nano safety and nano bio. Research at INM is performed in three fields: Nanocomposite Technology, Interface Materials, and Bio Interfaces.
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Possibilities for graphene-integrated polymer composites in dental prostheses ans medical implants

A larger proportion of our population is now living into their 80s and 90s and this has a great deal of influence on the frequency with which either partial and complete tooth loss occurs. There are other causes of edentulism outside of an ageing demographic of course - congenital absence, trauma, dental diseases and oral cancers all significantly contribute to it too. All of these factors, as well as increased interest in oral health within developing countries, are leading to a considerable growth in the value of the global dental prosthetic supply business. It is expected that this will be worth approximately $9.1 biliion by 2018, according to industry analysts Markets&Markets (an almost 50% increase on its current value). Around half of this will be related to fixed dental prostheses (either implant-supported bridges/crowns, tooth-supported bridges/crowns, inlays, onlays or veneers). If this the predicted increase in the market is to be witnessed, however, then major advances must be made in prothestic science. Numerous approaches have been taken to the construction of fixed dental prostheses, but existing material technologies have tended to fall short of expectations. The reason for this is an inherent lack of robustness, which leads to short operational lifespans being witnessed. Conversely, the period of time that prostheses need to function is being extended as the average life expectancy increases. There is an increasing demand within the dental industry for prosthetic materials which display increased overall resilience and permit greater longevity. One of the main problems associated with the fitting of patients with fixed dental prostheses is that of location. This stems from the fact they must be situated within the mouth - which proves to be an extremely demanding setting, where exposure to moisture, high temperatures, abrasion from toothbrushes and intake of food all have to be dealt with. These conditions can lead to complications, mechanical failures and contraindications occuring, all of which negate clinical success and over time mandate remedial work to restore the prosthetic to full working order - with associated cost and inconvenience. Then there is the issue of biocompatibility to consider. It is critical that any prostheses can coexist harmoniously with the organic tissues they are in contact with. The regularity with which failures currently occur prevents the specification of prostheses with operational lifespans which are in line with the patients (i.e. capable of functioning over decades rather than just years). This is something that must be satisfied before fixed dental prostheses are to gain widespread acceptance. To try and meet these requirements, a number of materials have been investigated in recent times - including metals (such as aluminium and tin), ceramics (zirconium and porcelain) and metal-ceramic hybrids. These materials have sadly proved inadequate in terms of their mechanical properties and their biocompatibly. Initiation of allergen sensitivity, potential for cytotoxicity, inability to blend in well enough with surrounding teeth/gums are other factors that need to be taken into account. Poly-ether-ether-ketone (PEEK) is an organic thermoplastic polymer material which is already employed in some medical implants due to its compatibility with human tissues. By integrating graphene into this polymer is hoped that the high degree of ruggedness that is mandated by dental use can be achieved. Graphene solutions provider 2-DTech and dental implant specialist Evodental are currently in the process of carrying out preliminary investigative work into the prospects of applying graphene within the field of dentistry. Utilising composites featuring high grade graphene they are looking to produce PEEK-based fixed dental prostheses with markedly increased longevity and improved clinical function. The objective of the project is to incorporate microscopic disc-shaped particles of graphene (known as graphene nanoplatelets) into the PEEK in order to form a graphene-reinforced polymer that is strong enough for dental prostheses (leading to a marked reduction in the number of clinical/surgical procedures needed to carry out repairs) while better matching the surface properties of the bone accommodating it and teeth around it. Combining an ultra-thin structure with high durability, the graphene-reinforced polymer envisaged by 2-DTech and Evodental could mitigate the deficiencies of current fixed dental prostheses construction methodologies. The resulting prostheses will benefit from the strength of graphene. Furthermore, since graphene coatings are completely transparent they have no effect on the prostheses’ visual appearance. Graphene-based polymer composites, such as the one described in this article, have the potential to revolutionise dentistry, enabling production of dental prostheses that are better able to cope with hostile operational environments. This will allow for greater prevalence of oral rehabilitation and thereby decrease the level of edentulism in the global population.
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Nanotechnology platform shows promise for treating pancreatic cancer

Scientists at UCLA’s California NanoSystems Institute and Jonsson Comprehensive Cancer Center have combined their nanotechnology expertise to create a new treatment that may solve some of the problems of using chemotherapy to treat pancreatic cancer. The study, published online in the journal ("Use of a Lipid-Coated Mesoporous Silica Nanoparticle Platform for Synergistic Gemcitabine and Paclitaxel Delivery to Human Pancreatic Cancer in Mice"), describes successful experiments to combine two drugs within a specially designed mesoporous silica nanoparticle that looks like a glass bubble. The drugs work together to shrink human pancreas tumors in mice as successfully as the current standard treatment, but at one twelfth the dosage. This lower dosage could reduce both the cost of treatment and the side effects that people suffer from the current method. Paclitaxel/Gemcitabine co-delivery inhibits pancreatic cancer Paclitaxel/Gemcitabine co-delivery inhibits pancreatic cancer. The study was led by Dr. Huan Meng, assistant adjunct professor of medicine, and Dr. Andre Nel, distinguished professor of medicine, both at the Jonsson Cancer Center. Pancreatic cancer, a devastating disease with a five-year survival rate of 5 percent, is difficult to detect early and symptoms do not usually appear until the disease is advanced. As a result, many people are not diagnosed until their tumors are beyond the effective limits of surgery, leaving chemotherapy as the only viable treatment option. The chemotherapy drug most often used for pancreas cancer is gemcitabine, but its impact is often limited. Recent research has found that combining gemcitabine with another drug called paclitaxel can improve the overall treatment effect. In the current method, Abraxane — a nano complex containing paclitaxel — and gemcitabine are given separately, which works to a degree, but because the drugs may stay in the body for different lengths of time, the combined beneficial effect is not fully synchronized. “The beauty of the silica nanoparticle technology is that gemcitabine and paclitaxel are placed together in one special lipid-coated nanoparticle at the exact ratio that makes them synergistic with one another when co-delivered at the cancer site, giving us the best possible outcome by using a single drug carrier,” Meng said. “This enables us to reduce the dose and maintain the combinatorial effect.” After the scientists constructed the silica nanoparticles, they suspended them in blood serum and injected them into mice that had human pancreas tumors growing under their skin. Other mice with tumors were given injections of saline solution (a placebo with no effect), gemcitabine (the treatment standard), and gemcitabine and Abraxane (an FDA-approved combination shown to improve pancreas cancer survival in humans). In the mice that received the two drugs inside the nanoparticle, pancreas tumors shrank dramatically compared with those in the other mice. Similar comparisons were made with mouse models, in which the human tumors were surgically implanted into the mice’s abdomens in order to more closely emulate the natural point of origin of pancreatic tumors and provide a better parallel to the tumors in humans. In these experiments, the tumors in the mice receiving silica nanoparticles shrank more than the comparative controls. Also, metastasis, or tumor spread, to nearby organs was eradicated in these mice. “Instead of just a laboratory proof-of-principle study of any cancer, we specifically attacked pancreatic cancer with a custom-designed nanocarrier,” said Nel, who is also associate director for research of the California NanoSystems Institute. “In our platform, the drugs are truly synergistic because we have control over drug mixing, allowing us to incorporate optimal ratios in our particles, making the relevance of our models very high and our results very strong.” Meng said the silica nanocarrier must still be refined for use in humans. The researchers hope to test the platform in human clinical trials within the next five years.
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