2015, Moerz, Sebastian T., Kraegeloh, Annette, Chanana, Munish, Kraus, Tobias

Citrate-stabilized gold nanoparticles (AuNP) agglomerate in the presence of hemoglobin (Hb) at acidic pH. The extent of agglomeration strongly depends on the concentration ratio [Hb]/[AuNP]. Negligible agglomeration occurs at very low and very high [Hb]/[AuNP]. Full agglomeration and precipitation occur at [Hb]/[AuNP] corresponding to an Hb monolayer on the AuNP. Ratios above and below this value lead to the formation of an unexpected phase: stable, microscopic AuNP–Hb agglomerates. We investigated the kinetics of agglomeration with dynamic light scattering and the adsorption kinetics of Hb on planar gold with surface-acoustic wave-phase measurements. Comparing agglomeration and adsorption kinetics leads to an explanation of the complex behavior of this nanoparticle–protein mixture. Agglomeration is initiated either when Hb bridges AuNP or when the electrostatic repulsion between AuNP is neutralized by Hb. It is terminated when Hb has been depleted or when Hb forms multilayers on the agglomerates that stabilize microscopic clusters indefinitely.

2018, Sankaran, Shrikrishnan, Zhao, Shifang, Muth, Christina, Paez, Julieta, Del Campo, Aránzazu

Living materials are an emergent material class, infused with the productive,adaptive, and regenerative properties of living organisms. Property regulation in living materials requires encoding responsive units in the living components to allow external manipulation of their function. Here, an optoregulated Escherichia coli (E. coli)-based living biomaterial that can be externally addressed using light to interact with mammalian cells is demonstrated. This is achieved by using a photoactivatable inducer of gene expression and bacterial surface display technology to present an integrin-specific miniprotein on the outer membrane of an endotoxin-free E. coli strain. Hydrogel surfaces functionalized with the bacteria can expose cell adhesive molecules upon in situ light-activation, and trigger cell adhesion. Surface immobilized bacteria are able to deliver a fluorescent protein to the mammalian cells with which they are interacting, indicating the potential of such a bacterial material to deliver molecules to cells in a targeted manner.

2000, Nonninger, Ralph

[no abstract available]

2017, Farrukh, Aleeza, Ortega, Felipe, Fan, Wenqiang, Marichal, Nicolás, Paez, Julieta I., Berninger, Benedikt, del Campo, Aránzazu, Salierno, Marcelo J.

Engineering of biomaterials with specific biological properties has gained momentum as a means to control stem cell behavior. Here, we address the effect of bifunctionalized hydrogels comprising polylysine (PL) and a 19-mer peptide containing the laminin motif IKVAV (IKVAV) on embryonic and adult neuronal progenitor cells under different stiffness regimes. Neuronal differentiation of embryonic and adult neural progenitors was accelerated by adjusting the gel stiffness to 2 kPa and 20 kPa, respectively.While gels containing IKVAV or PL alone failed to support long-term cell adhesion, in bifunctional gels, IKVAV synergized with PL to promote differentiation and formation of focal adhesions containing b1-integrin in embryonic cortical neurons. Furthermore, in adult neural stem cell culture, bifunctionalized gels promoted neurogenesis via the expansion of neurogenic clones. These data highlight the potential of synthetic matrices to steer stem and progenitor cell behavior via defined mechano-adhesive properties.

2014, Wählisch, Felix C., Peter, Nicolas J., Torrents Abad, Oscar, Oliveira, Mariana V.G., Schneider, Andreas S., Schmahl, Wolfgang, Griesshaber, Erika, Bennewitz, Roland

We investigated the friction and wear behavior as well as the mechanical properties of the periostracum of Mytilus sp. Tribological properties were determined with a reciprocal sliding microtribometer, while mechanical characterization was performed using a nanoindenter. Measurements were performed in dry and wet conditions. On the dry periostracum we found a low friction coefficient of 0.078 ± 0.007 on the young parts and a higher one of 0.63 ± 0.02 on the old parts of the shell. Under wet, saline, conditions we only observed one average coefficient of friction of 0.37 ± 0.01. Microscopic ex situ analysis indicated that dry periostracum wore rather rapidly by plowing and fatigue, while it exhibited a high wear resistance when immersed in salt water. The Young’s modulus and hardness of the periostracum were also investigated in both dry and wet conditions. Under dry conditions the Young’s modulus of the periostracum was 8 ± 3 GPa, while under wet conditions it was 0.21 ± 0.05 GPa. The hardness of dry periostracum samples was 353 ± 127 MPa, whereas the hardness of wet samples was 5 ± 2 MPa. It was found that, in the wet state, viscous behavior plays a significant role in the mechanical response of the periostracum. Our results strongly indicate that the periostracum can provide an important contribution to the overall wear resistance of Mytilus sp. shell.

2011, Veith, Michael, Belot, Celine, Huch, Volker

In the mononuclear title compound, [Tb(C13H9OS3)3(C4H8O)3]·C4H8O, the lanthanide cation is located on a threefold rotation axis and is surrounded by electron-rich ligands in an approximately octahedral geometry. One of the thienyl groups and the bound THF are disordered with 0.5:0.5 occupancy. The free THF is disordered around the threefold axis.

2006, INM

[no abstract available]

2015, Silina, Yuliya E., Fink-Straube, Claudia, Hayen, Heiko, Volmer, Dietrich A.

In this study, we propose a simple and rapid technique for characterization of free fatty acids and triacylglycerides (TAG) based on palladium nanoparticular (Pd-NP) surface-assisted laser desorption/ionization (SALDI) mass spectrometry (MS). The implemented Pd-NP material allowed detection of free fatty acids and TAGs exclusively as [M + K]+ ions in positive ion mode. Under negative ionization conditions, unusual trimetric structures were generated for free fatty acids, while TAGs underwent irreproducible degradation reactions. Importantly, the mass spectra obtained from Pd-NP targets in positive ion mode were very clean without interferences from matrix-derived ions in the low m/z range and readily enabled the detection of intact TAGs in vegetable oils without major fragmentation reactions as compared to conventional MALDI-MS, requiring only a minimal amount of sample preparation.

2013, Lee, Juseok

The first part of this thesis is dealing with gravity effect on the synthesis of biphasic core/shell Al/Al2O3 composites. By chemical vapor deposition of the precursor [tBuOAlH2]2 at 400°C, only spherical nanoparticles were observed on the substrate surface. The formation of nanowires was observed at 600°C. It is a good agreement with our previous results on earth condition and there is no gravity impact on the chemical reaction. At increased gravity levels, the nanoparticles formed large clusters and the nanowires showed bundle formation while the nanowires at microgravity have predominantly linear structures. It is proposed that the chaotic nature of nanowires and cluster formation of nanoparticles were caused by a dominance of gravity over the thermal creep. In the second part the use of Al/Al2O3 nanowire layers for bio applications is considered. Contact cell guidance and alignment were studied to understand how cells recognize and respond to certain surface patterns. Linear micro channels were created on Al/Al2O3 layer by direct laser writing and laser interference patterning. Although surface topography was altered, the surface chemistry was always identical (Al2O3) due to the unique core/shell nature of Al/Al2O3 nanowires. Human osteoblast, normal human dermal fibroblast and neuronal cells were cultured and investigated. The results indicate that different cell types show diverse responses to the topography independent from the surface chemistry of the material.

2009, Veith, Michael

[no abstract available]