DEA-based deformable cell culture system

We present a deformable cell culture system based on dielectric elastomer actuator (DEA). Understanding how the mechanical environment can affect cells functions could lead to significant advances in diseases diagnosis and drug development. Most available technologies offer low screening throughput, an important limitation considering the statistical nature of cellular studies. We previously reported an array of micro-DEAs for cell stretching application. Our DEA-based solution has the potential to replace current technologies and overcome the high screening throughput limitation. We present a new generation of devices, developed to better address cell biologists requirements. Two different devices were developed to apply periodic (1-5Hz) compressive or tensile strain greater than 10% on a 2mm x 2mm biological sample. Their original designs exploit non-equibiaxial pre-stretch of a silicone membrane and stress induced in passive regions of DEAs. Our technology is now compatible with high resolution optical microscopy for real time monitoring of morphology and chemical activity of the biological sample. This new generation of devices also significantly improves the electric field confinement and provides a fully biocompatible environment

Ultrathin ceramic membranes as scaffolds for functional cell coculture models on a biomimetic scale

Epithelial tissue serves as an interface between biological compartments. Many in vitro epithelial cell models have been developed as an alternative to animal experiments to answer a range of research questions. These in vitro models are grown on permeable two-chamber systems; however, commercially available, polymer-based cell culture inserts are around 10 μm thick. Since the basement membrane found in biological systems is usually less than 1 μm thick, the 10-fold thickness of cell culture inserts is a major limitation in the establishment of realistic models. In this work, an alternative insert, accommodating an ultrathin ceramic membrane with a thickness of only 500 nm (i.e., the Silicon nitride Microporous Permeable Insert [SIMPLI]-well), was produced and used to refine an established human alveolar barrier coculture model by both replacing the conventional inserts with the SIMPLI-well and completing it with endothelial cells. The structural–functional relationship of the model was evaluated, including the translocation of gold nanoparticles across the barrier, revealing a higher translocation if compared to corresponding polyethylene terephthalate (PET) membranes. This study demonstrates the power of the SIMPLI-well system as a scaffold for epithelial tissue cell models on a truly biomimetic scale, allowing construction of more functionally accurate models of human biological barriers

Thin-film dielectric elastomer sensors to measure the contraction force of smooth muscle cells

The development of thin-film dielectric elastomer strain sensors for the characterization of smooth muscle cell (SMC) contraction is presented here. Smooth muscle disorders are an integral part of diseases such as asthma and emphysema. Analytical tools enabling the characterization of SMC function i.e. contractile force and strain, in a low-cost and highly parallelized manner are necessary for toxicology screening and for the development of new and more effective drugs. The main challenge with the design of such tools is the accurate measurement of the extremely low contractile cell forces expected as a result of SMC monolayer contraction (as low as ~ 100 μN). Our approach utilizes ultrathin (~5 μm) and soft elastomer membranes patterned with elastomer-carbon composite electrodes, onto which the SMCs are cultured. The cell contraction induces an in-plane strain in the elastomer membrane, predicted to be in the order 1 %, which can be measured via the change in the membrane capacitance. The cell force can subsequently be deduced knowing the mechanical properties of the elastomer membrane. We discuss the materials and fabrication methods selected for our system and present preliminary results indicating their biocompatibility. We fabricate functional capacitive senor prototypes with good signal stability over the several hours (~ 0.5% variation). We succeed in measuring in-plane strains of 1 % with our fabricated devices with good repeatability and signal to noise ratio

Detection and investigation of biological molecules by fourier transform infra-red spectroscopy

Method and apparatus to study biological molecules or biological components at or in self-assembled monolayers (SAMs) on metal surfaces (2) such as gold in aqueous environments (6) using attenuated total internal reflection Fourier transform infra-red (ATR-FTIR) spectroscopy are described. Said method may be used for e.g. the screening for effective substances suitable as agonists or antagonists or - if performed time resolved - for studying kinetics of interactions of e.g. biological molecules adsorption and desorption processes or for the development of materials and surfaces for biological or medical applications

Laterale Mikrostrukturierung organischer Thiolatschichten durch Selbstorganisation

The lateral microstructure was studied of a Langmuir film of palmitic acid and bis[8-(1,2-dipalmitoyl-sn-glycero-3-phosphoryl)-3,6-dioxaoctyl] disulfide (I), I and w-mercaptoundecanoic acid (II), and I, II, and a Cu complex with II on Au. The self-organization effects of I are described. [on SciFinder (R)

Biologically addressable monolayer structures formed by templates of sulfur-bearing molecules

We demonstrate that the combined application of Langmuir-Blodgett and self-assembly techniques allows the fabrication of patterns with contrasting surface properties on gold substrates. The process is monitored using fluoroscence microscopy and surface plasmon spectroscopy and microscopy. These structures are suitable for the investigation of biochem. processes at surfaces and in ultrathin films. Two examples of such processes are shown. In the first example, the structures are addressed through the binding of a monoclonal antibody to a peptide. This demonstrates the formation of self-assembled monolayers by cysteine-bearing peptides on gold, and the directed binding of proteins to the structured layers. A high contrast between specific and unspecific binding of proteins is obsd. by the patterned presentation of antigens. Such films possess considerable potential for the design of multichannel sensor devices. In the second example, a structured phospholipid layer is produced by controlled self-assembly from vesicle soln. The structures created, areas of phospholipid bilayer surrounded by a matrix of phospholipid monolayer, allow formation of a supported bilayer which is robust and strongly bound to the gold support, with small areas of free-standing bilayer which very closely resemble a phospholipid cell membrane. [on SciFinder (R)

Detection of supported lipid layers with the acoustic Love waveguide device: application to biosensors

The formation of supported lipid mono- and bilayers on a thiol-coated surface was monitored by utilising the acoustic Love waveguide device. The detection of the lipid layers was used as a model system for relating the phase response to the deposited mass and studying the sensor's response to the regeneration of the surface. The sensitivity of the acoustic device revealed that, in addn. to the mass change occurring during the deposition of the lipid layers, the viscoelastic properties of the interface change significantly. Finally, a biosensor system was studied, where the antigen was self-assembled on the device surface and the binding and further displacement of its complementary antibody monitored. [on SciFinder (R)

Antibody Binding to a Functionalized Supported Lipid Layer: A Direct Acoustic Immunosensor

A direct immunosensor has been developed using an acoustic wave device as a transducer. The device is based on an acoustic waveguide geometry that supports a Love wave. The biorecognition surface, formed on a gold layer, consisted of a biotinylated supported lipid layer which specifically bound streptavidin and, subsequently, biotinylated goat IgG. The modified surface was used as a model immunosensor and successfully detected rabbit anti-goat IgG in the concn. range 3*10-8-10-6 M. Using the anti-goat IgG binding isotherm and the time-resolved measurements of antibody binding, both the binding and rate consts. of the reaction were detd. The specificity of each binding step was studied with the acoustic wave device, and it was concluded that the phospholipid bilayer showed a good suppression of nonspecific binding. Comparative measurements using surface plasmon resonance allowed the response of the immunosensor to be quant. correlated with mass binding to the surface. [on SciFinder (R)

Direct Observation of Self-Assembled Monolayers, Ion Complexation, and Protein Conformation at the Gold/Water Interface: An FTIR Spectroscopic Approach

A simple approach to the in situ measurement of IR spectra of self-assembled monolayers (SAMs) on gold in an aq. environment is described. A thin gold film (3-5 nm) on the surface of a germanium internal reflection element is used as a substrate for the self-assembly of a monolayer of a chelating thioalkane. High signal-to-noise spectra are obtained, allowing identification of the chem. groups present in the SAM. Complexation of ions by the SAM can be monitored, and the secondary conformation of His-tagged proteins bound to the SAM can be obsd. [on SciFinder (R)

Micrometer-long gold nanowires fabricated using block copolymer templates

Micrometer-long gold nanowires were fabricated via self-assembly. Diblock copolymer films served as templates for the selective adsorption of 10 nm gold nanoparticles from solution to form well-defined nanostructures. An oxygen plasma treatment induced aggregation of the nanoparticles and the formation of continuous gold nanostructures. The electrical continuity of the nanostructures was observed using scanning electron microscopy