Adsorption and superficial transport of oil on biological and bionic superhydrophobic surfaces: a novel technique for oil-water separation.

Superhydrophobicity is a physical feature of surfaces occurring in many organisms and has been applied (e.g. lotus effect) in bionic technical applications. Some aquatic species are able to maintain persistent air layers under water (Salvinia effect) and thus become increasingly interesting for drag reduction and other 'bioinspired' applications. However, another feature of superhydrophobic surfaces, i.e. the adsorption (not absorption) and subsequent superficial transportation and desorption capability for oil, has been neglected. Intense research is currently being carried out on oil-absorbing bulk materials like sponges, focusing on oleophilic surfaces and meshes to build membranes for oil-water separation. This requires an active pumping of oil-water mixtures onto or through the surface. Here, we present a novel passive, self-driven technology to remove oil from water surfaces. The oil is adsorbed onto a superhydrophobic material (e.g. textiles) and transported on its surface. Vertical and horizontal transportation is possible above or below the oil-contaminated water surface. The transfer in a bioinspired novel bionic oil adsorber is described. The oil is transported into a container and thus removed from the surface. Prototypes have proven to be an efficient and environmentally friendly technology to clean oil spills from water without chemicals or external energy supply. This article is part of the theme issue 'Bioinspired materials and surfaces for green science and technology (part 3)'.

Fast synthesis of ultrathin ZnO nanowires by oxidation of Cu/Zn stacks in low-pressure afterglow.

The synthesis of ultrathin, single-crystalline zinc oxide nanowires was achieved by treating in a flowing microwave plasma oxidation process, zinc films coated beforehand by a sputtered thin buffer layer of copper. The aspect ratio of the nanowires can be controlled by the following experimental parameters: treatment duration, furnace temperature, oxygen concentration. An average diameter of 6 nm correlated with a mean length of 750 nm can be reached with a fairly high surface number density for very short treatments, typically less than 1 min. The oxidized samples are characterized by means of SEM, XRD, SIMS, HRTEM and EDX techniques. Structural characterization reveals that these nanowires are single-crystalline, with the wurtzite phase of ZnO. Nanowires are only composed of ZnO without copper particles inside or at the end of the nanowires. Temperature-dependent photoluminescence measurements confirm that ZnO nanowires are of high crystalline quality and thin enough to produce quantum confinement.

[Materials/Biomaterials in Clinical Practice - a Short Review and Current Trends]. / Werkstoffe/Biomaterialien in der interventionellen und operativen Medizin ­ eine kurze Übersicht und aktuelle Trends.

Biomaterials play a major role in interventional medicine and surgery. However, the development of biomaterials is still in its early phases in spite of the huge progress made within the last decades. On the one hand, this is because our knowledge of the molecular and cellular processes associated with biomaterials is still increasing exponentially. On the other hand, a wide variety of advanced materials with highly interesting properties is being developed currently. This review provides a short introduction into the variety of materials in use as well as their application in interventional medicine and surgery. Also the importance of biomaterials for tissue engineering in the field of regenerative medicine and the functionalisation of biomaterials, including sterilisation methods are discussed. For the future, an even broader interdisciplinary scientific collaboration is necessary in order to develop novel biomaterials and facilitate their translation into clinical practice.

Tubular woven narrow fabrics for replacement of cruciate ligaments.

The human knee is one of the most frequently injured joints. More than half of these injuries are related to a failure of the anterior cruciate ligament. Current treatments (allogeneic and autologous) bear several disadvantages which can be overcome through the use of synthetic structures. Within the scope of this paper the potential of tubular woven fabrics for the use as artificial ligaments has been evaluated. Twelve fabrics made of polyethylene terephthalate and polytetrafluoroethylene were produced using shuttle weaving technology. Mechanical and biological properties of the fabrics were assessed using static tensile testing and cytotoxicity assays. The results obtained within this study show that woven tubular fabrics can be potentially used as artificial ligament structures as they can provide the desired medical and mechanical properties for cruciate ligament replacements. Through the choice of material and weaving parameters the fabrics' tensile properties can imitate the stress-strain characteristic of the human cruciate ligament. Further assessments in terms of cyclic loading behavior and abrasion resistance of the material are needed to evaluate the success in long term implantation.

Characterization of textile electrodes and conductors using standardized measurement setups.

Textile electrodes and conductors are being developed and used in different monitoring scenarios, such as ECG or bioimpedance spectroscopy measurements. Compared to standard materials, conductive textile materials offer improved wearing comfort and enable long-term measurements. Unfortunately, the development and investigation of such materials often suffers from the non-reproducibility of the test scenarios. For example, the materials are generally tested on human skin which is difficult since the properties of human skin differ for each person and can change within hours. This study presents two test setups which offer reproducible measurement procedures for the systematic analysis of textile electrodes and conductors. The electrode test setup was designed with a special skin dummy which allows investigation of not only the electrical properties of textile electrodes but also the contact behavior between electrode and skin. Using both test setups, eight textile electrodes and five textile conductors were analyzed and compared.

Suspension-adapted Chinese hamster ovary-derived cells expressing green fluorescent protein as a screening tool for biomaterials.

Synthetic biomaterials play an important role in regenerative medicine. To be effective they must support cell attachment and proliferation in addition to being non-toxic and non-immunogenic. We used a suspension-adapted Chinese hamster ovary-derived cell line expressing green fluorescent protein (GFP) to assess cell attachment and growth on synthetic biomaterials by direct measurement of GFP-specific fluorescence. To simplify operations, all cell cultivation steps were performed in orbitally-shaken, disposable containers. Comparative studies between this GFP assay and previously established cell quantification assays demonstrated that this novel approach is suitable for rapid screening of a large number of samples. Furthermore the utility of our assay system was confirmed by evaluation of cell growth on three polyvinylidene fluoride polymer scaffolds that differed in pore diameter and drawing conditions. The data presented here prove the general utility of GFP-expressing cell lines and orbital shaking technology for the screening of biomaterials for tissue engineering applications.