Arie Bruinink

C60 fullerene : A powerful antioxidant or a damaging agent? The importance of an in-depth material characterization prior to toxicity assays

Since the discovery of fullerenes in 1985, these carbon nanospheres have attracted attention regarding their physico/chemical properties. Despite little knowledge about their impact on the environment and human health, the production of fullerenes has already reached an industrial scale. However, the toxicity of C(60) is still controversially discussed. The aim of this study was to clarify the biological effects of tetrahydrofuran (THF) suspended C(60) fullerene in comparison to water stirred C(60) fullerene suspensions. Beyond that, we analyzed the effects on the Crustacea Daphnia magna an indicator for ecotoxicological effects and the human lung epithelial cell line A549 as a simplified model for the respiratory tract. We could demonstrate that water-soluble side products which were formed in THF nC(60) suspension were responsible for the observed acute toxic effects, whereas fullerenes themselves had no negative effect regardless of the preparative route on either A549 cell in vitro or D. magna in vivo.

Surface grafting of a thermoplastic polyurethane with methacrylic acid by previous plasma surface activation and by ultraviolet irradiation to reduce cell adhesion

The material performance, in a biological environment, is mainly mediated by its surface properties and by the combination of chemical, physical, biological, and mechanical properties required, for a specific application. In this study, the surface of a thermoplastic polyurethane (TPU) material (Elastollan(®)1180A50) was activated either by plasma or by ultra-violet (UV) irradiation. After surface activation, methacrylic acid (MAA) was linked to the surface of TPU in order to improve its reactivity and to reduce cell adhesion. Grafted surfaces were evaluated by X-ray photoelectron spectroscopy (XPS), by atomic force microscopy (AFM) and by contact angle measurements. Blood compatibility studies and cell adhesion tests with human bone marrow cells (HBMC) were also performed. If was found that UV grafting method led to better results than the plasma activation method, since cell adhesion was reduced when methacrylic acid was grafted to the TPU surface by UV.

From implantation to degradation — are poly (l-lactide)/multiwall carbon nanotube composite materials really cytocompatible?

UNLABELLED Poly (l-lactide)s (PLLA) biodegradable properties are of special value in orthopaedic applications, but its mechanical strength limits its usage. To overcome this PLLA can be reinforced by multiwall carbon nanotubes (MWCNT). In this study the PLLA and MWCNT were combined to prepare nanostructured composites (nanocomposite) at 0, 0.1, 0.5 and 1wt.% reinforcement. The in vitro biocompatibility of these PLLA/MWCNT nanocomposites was evaluated taking into account the various stages of implantation including nanocomposite degradation. PLLA/MWCNT nanocomposites were highly biocompatible with human bone marrow stromal cells (HBMC). The potential surface degradation product, MWCNT, did not induce toxic responses on HBMC. However, the combination of MWCNT with lactic acid, resembling release after bulk degradation, significantly inhibited HBMC proliferation and activity. This study demonstrates the importance of comprehensive evaluations of novel materials for medical applications in predicting possible adverse effects during nanocomposite degradation. FROM THE CLINICAL EDITOR This study scrutinizes the cytocompatibility of poly-L-lactide reinforced by multiwall carbon nanotubes, and concludes that the combination of MWCNT with lactic acid significantly inhibited human bone marrow stromal cell proliferation and activity, highlighting the importance of comprehensive evaluations of novel materials.

Biological characterization of woven fabric using two- and three-dimensional cell cultures†

The integration and long-term functional retention of tissue implants are both strongly linked to the implant material characteristics. As a first approach, the cytocompatibility and bioactivity of such materials are evaluated using in vitro-based cell culture models. Typically, in vitro bioactivity is assessed by seeding single cells onto the test material to evaluate certain parameters such as cell adhesion, survival, proliferation, and functional differentiation. Probably, due to the reduction from three dimensional (3D) toward the two dimensional (2D) situation the data obtained from 2D culture models falls short of predicting the in vivo behavior of the biomaterial in question. In this study, a three dimensional (3D) in vitro cell culture model was applied to evaluate the bioactivity of well characterized fiber-based scaffolds using scaffold colonization as a bioactivity indicator. Cell behavior in this culture model was evaluated against a classical comparable, 2D cell culture system using polyethylene terephthalat and polyamide 6.6 fabrics. By using the 3D culture model, however, differences in cell population performance as a function of fiber diameter and mesh angle were evident. The use of 3D cell culture model clearly outperformed typical cell culture setup as means to evaluate cell population-scaffold interaction.

Improving cell adhesion: development of a biosensor for cell behaviour monitoring by surface grafting of sulfonic groups onto a thermoplastic polyurethane

The surface properties of a material in combination with the mechanical properties are responsible for the material performance in a biological environment as well as the behaviour of the cells which contact with the material. Surface properties such as chemical, physical, biological play an important role in the biomaterials filed. In this work, the surface of a thermoplastic polyurethane film (Elastollan®1180A50) was tailored with sulfonic groups by grafting [2-(methacryloxyl)ethyl]-dimethyl-(3-sulfopropyl)-ammonium hydroxide (SB) after a previous surface activation either by Argon plasma or by ultra-violet irradiation. This surface modification had the purpose of improving cell adhesion in order to develop a biosensor able to monitor cell behaviour. The surfaces were characterized by X-ray photoelectron spectroscopy, by atomic force microscopy and by contact angle measurements in order to evaluate the efficiency of the modification. Additionally, blood compatibility studies and cell adhesion tests with human bone marrow cells were performed. These methods allowed the grafting of SB and the results indicate that a higher density of grafting was achieved with previous surface plasma treatment than with UV irradiation. However, for both techniques, the presence of SB functional groups led to a decrease of hydrophobicity and roughness of the surface, together with an improvement of the materials biological performance.

The agar diffusion scratch assay - A novel method to assess the bioactive and cytotoxic potential of new materials and compounds

A profound in vitro evaluation not only of the cytotoxic but also of bioactive potential of a given compound or material is crucial for predicting potential effects in the in vivo situation. However, most of the current methods have weaknesses in either the quantitative or qualitative assessment of cytotoxicity and/or bioactivity of the test compound. Here we describe a novel assay combining the ISO 10993-5 agar diffusion test and the scratch also termed wound healing assay. In contrast to these original tests this assay is able to detect and distinguish between cytotoxic, cell migration modifying and cytotoxic plus cell migration modifying compounds, and this at higher sensitivity and in a quantitative way.

Harvesting pre-polarized macrophages using thermo-responsive substrates

In the cell culture environment macrophages are highly adherent cells. Currently used methods to harvest macrophages have the disadvantage of reducing cell viability and their ability to re-attach after seeding. Although thermo-responsive surfaces have been employed to harvest cell sheets no reports are available to use these to harvest (pre-polarized) macrophages. We show that this method significantly improves the yield of living macrophages and percentage of subsequent cell reattachment, whilst having a minimal effect on the cell phenotype.

Erweiterung der Biokompatibilität auf Ökosysteme und Werkstoffe

In der Schweiz fallen pro Jahr uber 8.3 Mio t Abfalle an, die sich aus Siedlungsabfallen (2.8 Mio t, 1994), deponierten Abfallen (z. B. Bauschutt, 3 Mio t), Sonderabfallen (0.35 Mio t), Klarschlamm (getrocknet, 0.25 Mio t) und verwertbaren Abfallen (1.9 Mio t) zusammensetzen [1]. In einem internationalen Vergleich liegt die Schweiz mit einer jahrlich anfallenden Menge von 441 kg pro Einwohner an funfter Stelle in der Produktion von Hausmull (Abb. 77.1).