Name: thin film composite silicon elastomers for cell culture and skin applications: manufacturing and characterization
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Description: Watch this Scientific Journal Video about Thin Film Composite Silicon Elastomers for Cell Culture and Skin Applications: Manufacturing and Characterization at JoVE.com

Martin Danner is acknowledged for his assistance in preparing samples and establishment of cell culture procedures. The authors would like to thank Biesterfeld Spezialchemie GmbH (Hamburg, Germany), especially Robert Radsziwill for continuous support and discussions. The research leading to these results has received funding from the European Research Council under the European Union&#39;s Seventh Framework Programme (FP/2007-2013) /ERC Grant Agreement n. 340929.

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The authors have nothing to disclose.

The design of composite structures enables the simple adjustment of material properties, such as Young&#39;s modulus or the thickness of the samples. The Young&#39;s modulus of PDMS can be effectively changed in a wide range by either altering the mixing ratio between the two components or manufacturing of blends using a different silicone elastomer30,31. The described methods are not limited to the PDMS&#39;s used in the current investigation, but especially the adhesive performance depends strongly on the specific type used. A critical step within this protocol is the manufacturing process of the composite films (Figure 1). It was shown that thickness of the films affects significantly the adhesion behavior of the films on different substrates, including skin (Figure 5 and Figure 6). In addition to the film thickness, time and temperature during the curing process affects the material properties32. Therefore, parameters as the thickness of the polymeric layers have to be carefully adapted and verified.
Analysis of the adhesive properties of the thin films was performed with normal force adhesion measurements using two glass substrates with different surface roughness up to Ra = 0.338 &#181;m (Figure 3). In general, roughness impacts significantly the adhesion of surfaces, especially of elastic materials33,34. The roughness of glass can be easily varied by grinding with sandpaper of different asperity sizes, therefore allowing the fabrication of substrates exhibiting higher roughness values21. In addition, other materials, for example epoxy resin can be used for the production of substrates15,35. This might be an important modification strategy of the presented protocol. For example, if substrates exhibiting different surface free energies are needed or specific topographies are required. Here, pull-off stress and work of separation of the thin films manufactured of PDMS and SSA were analyzed with a custom-built setup (macroscopic adhesion measurement device (MAD, Figure 4)).36 Optical alignment of substrate and indenter is a critical step for the analysis of the measurement results. Therefore, adjustment of the tilt angle needs to be performed with the goniometer, as precise as possible. This can be achieved with sufficient precision by manually bringing the substrate into contact with the film surface until a horizontal contact is achieved.
In the current protocol the hold time was kept constant at one second (Figure 5 and Figure 7). Especially for the investigation of the adhesive performance of an elastic film to a rough substrate surface, an extension of the hold time provides additional information. For example, an increase in pull-off stress with increasing hold time has been reported8. In addition to the measurements performed in the current protocol, other methods, for example peel tests could be performed, allowing a more comprehensive investigation of adhesion performance37.
The adhesive properties of composite films exhibiting different film thicknesses of the soft skin adhesive were determined (Figure 7). Our results are in line with published data, showing that a decrease of film thickness lead to an increase of the pull-off stress as the confinement, i.e., the ratio between substrate diameter and film thickness, increases38,39. Based on these results and the data depicted in Figure 7, we conclude that composite films with a total thickness of approx. 100 &#181;m (a thickness of the SSA layer of approx. 60 &#181;m applied to a PDMS film with a thickness of approx. 40 &#181;m) exhibit favorable adhesion properties on rough surfaces.
Next, experiments related to the biological characterization have been performed on pristine composite films and plasma treated composite films (Figure 8). Plasma treatment of silicon elastomers is an often applied, versatile technique to increase the hydrophilic properties of surfaces and promoting cellular attachment and cellular spreading40,41. Silicones are well known for their low toxicity and high biostability but may contain residual monomers or catalysts which might influence physiological processes, leading also to cytotoxicity42,43. In the conducted experiments we have observed less than 5% cytotoxicity using LDH release as an indicator and a Trypan Blue exclusion assay. In the presented protocol, the entire cellular population, including cellular aggregates detached form the surface has been analyzed for proliferation analysis (Figure 9B). A modification of the protocol could produce more differentiated results. For each sample, the supernatant containing detached cellular aggregates could be transferred to a separate reaction tube and not combined with the cells enzymatically removed from the polymer surface. This would allow the exact assessment of cells attached to the surface and eventually reveal a more detailed determination of the influence of the polymers on the cellular adhesion process. In addition to the immunocytochemical methods presented here, cells might be harvested for investigation with immunoblot methods, allowing a detailed quantitative assessment of protein expression.
In summary, we have established manufacturing conditions for the production of thin elastomeric composite films for applications in advanced cell culture research. Additionally, these thin films possess high adaptability to skin roughness, enabling sophisticated design of skin adhesives.

In this protocol, detailed methods for manufacturing of thin elastomer films are presented. The widely available doctor blade technique has been used for the production of thin composite films. The manufacturing technique has been performed on polyethylenterephtalate (PET) foils, enabling subsequent production of these films in large scale. Emphasis of this protocol is the assessment of reproducibility, precise manufacturing of the different layers of the composite films and determination of the biological and adhesion properties of the final composite patch. The silicone elastomer poly-(dimethylsiloxane) (PDMS) is extensively used in biomedical technology, including production of skin adhesives, microfluidics applications and additional research fields1,2,3,4. Recently, another subclass of PDMS, so called Soft Skin Adhesives (SSAs) have been introduced, particular for gentle skin bonding and de-bonding.
Silicone SSAs are vinyl functionalized elastomers, differing from analogous polymers by the absence of reinforcing silica5. Similar to other PDMS, SSA&#39;s Young&#39;s modulus can be adapted in a wide range by modulating cross-linker concentration or curing time6,7,8. This change in Young&#39;s modulus of silicone elastomers affects the adhesive properties of the material significantly and has also profound consequences on prokaryotic and eukaryotic cells cultured on the surface9,10,11. On the cellular biological level, it was shown, that eukaryotic cells respond on the signal transduction level to a modulation of the matrix elasticity or thickness of the surface9,10,12,13,14. Therefore, a broad interest in cell culture applications of polymers with tunable mechanical properties exist. Importantly, the intrinsically low surface energy of silicone based elastomers does not provide optimal conditions for cell culture of eukaryotic cells. Oxygen plasma treatment is a widely used technique to increase PDMS low surface energy temporarily, leading to an enhancement of its pull-off strength, decreased surface adsorption of molecules, while in parallel promoting attachment, spreading and proliferation of eukaryotic cells15,16,17,18.
In addition to the materials properties, the surface topography significantly affects cellular adhesion and the adhesive interaction between two materials19,20,21,22. Surface roughness has several effects on the contact formation between two surfaces: reduction of the contact area, high stored elastic energy surrounding asperities as well as influence on the crack propagation can alter the adhesive strength23,24. Adhesion of self-adhesive films to human skin is an emerging application field, e.g., wound dressings, fixation of ECG electrodes or other wearable electronic devices25,26,27,28. To measure the adhesive performance of self-adhesives in relation to surface topography, glass substrates with varying degrees of roughness can be used in normal adhesion measurements8,21. Here, two glass substrates have been selected to investigate the adhesive properties of the polymer films. First, composite films with a PDMS backing layer in a mixing ratio of 10 to 1 weight parts covered by PDMS with different mixing ratio were characterized. In a second step a adhesive SSA layer was prepared with equal weight amounts of both components and with varying film thickness on top of a supporting PDMS film.

<table><tbody><tr><td>2-Propanol, 97%</td><td>Stockmeier Chemie</td><td>1000452610000</td><td>Isopropanol</td></tr><tr><td>Abrasive diamnod hand pad</td><td>Bohle</td><td>MO 5007522</td><td>Grit: 220</td></tr><tr><td>Accutase</td><td>Capricorn Scientific</td><td>ACC-1B</td><td></td></tr><tr><td>Albumin Fraktion V</td><td>Roth</td><td>0163.2</td><td>BSA</td></tr><tr><td>Alexa Fluor 488 Phalloidin</td><td>ThermoFischer Scientific</td><td>A12379</td><td>highly toxic</td></tr><tr><td>Aquamount</td><td>Polysciences</td><td>18606-20</td><td>water soluble mounting medium</td></tr><tr><td>CytoTox-ONE Homogeneous Membrane Integrity Assay</td><td>Promega</td><td>G7890</td><td></td></tr><tr><td>DPBS, without Ca&lt;sup&gt;2+&lt;/sup&gt;, Mg&lt;sup&gt;2+&lt;/sup&gt;</td><td>ThermoFischer Scientific</td><td>14190094</td><td></td></tr><tr><td>Fetal bovine serum gold</td><td>GE Health Care Life Science</td><td>A15-151</td><td>FBS</td></tr><tr><td>Goniometer OCA35</td><td>Dataphysics</td><td></td><td>for the determination of the static water contact angle</td></tr><tr><td>Hoechst Dye 33342</td><td>Sigma-Aldrich</td><td>B1155-100MG</td><td>bisBenzimide H 33342 trihydrochloride, highly toxic</td></tr><tr><td>Microscope Axiovert 25</td><td>Zeiss</td><td></td><td>Microscope used for cell culture documentation</td></tr><tr><td>Microscope Eclipse LV100ND</td><td>Nikon</td><td></td><td>Microscope used for film thickness determination</td></tr><tr><td>Paraformaldehyde, aqueous solution 16%</td><td>Electron Microscopy Sciences</td><td>RT 15710</td><td>electron microscopy grade</td></tr><tr><td>penicillin und streptomycin solution</td><td>Sigma-Aldrich</td><td>P4333-100ML</td><td></td></tr><tr><td>Phenom XL Scanning Electron Microscope (SEM)</td><td>Phenom</td><td></td><td></td></tr><tr><td>Poly-(vinyl alcohol) 4-88, MW 31000</td><td>Sigma-Aldrich</td><td>81381-1KG</td><td>Mowiol 4-88</td></tr><tr><td>Poly-dimethyl siloxanes, Sylgard 184</td><td>Dow Corning</td><td>(400)000108351397</td><td>PDMS</td></tr><tr><td>RPMI 1640 basal medium</td><td>ThermoFischer Scientific</td><td>21875034</td><td></td></tr><tr><td>soft skin adhesive (SSA)</td><td>Dow Corning</td><td>(400)000108251792</td><td>MG 7-9800 Soft Skin Adhesive (SSA)</td></tr><tr><td>speed mixer DAC 600.2 VAC-P</td><td>Hauschild</td><td></td><td></td></tr><tr><td>stylus profilomter</td><td>Zeiss</td><td></td><td>Model: SURFCOM 1500SD3</td></tr><tr><td>Tecan Infinite M200 pro</td><td>Tecan</td><td></td><td>fluorescence plate reader</td></tr><tr><td>Triton X 100</td><td>Calbiochem</td><td>648466</td><td></td></tr><tr><td>Trypan Blue solution</td><td>Sigma-Aldrich</td><td>T8154-100ML</td><td>highly toxic</td></tr><tr><td>Trypsin/EDTA solution</td><td>PAN-Biotech</td><td>P10-023500</td><td>0.05% Trypsin, 0.02% EDTA in PBS</td></tr><tr><td>UV glue</td><td>Bohle</td><td>BO MV76002</td><td>medium viscosity</td></tr></tbody></table>

thin film composite silicon elastomers for cell culture and skin applications: manufacturing and characterization

In this protocol, we present methods to fabricate thin elastomer composite films for advanced cell culture applications and for the development of skin adhesives. Two different poly-(dimethyl siloxanes) (PDMS and soft skin adhesive (SSA)), have been used for in depth investigation of biological effects and adhesive characteristics. The composite films consist of a flexible backing layer and an adhesive top coating. Both layers have been manufactured by doctor blade application technique. In the present investigation, the adhesive behavior of the composite films has been investigated as a function of the layer thickness or a variation of the Young&#39;s modulus of the top layer. The Young&#39;s modulus of PDMS has been changed by varying the base to crosslinker mixing ratio. In addition, the thickness of SSA films has been varied from approx. 16 &#181;m to approx. 320 &#181;m. Scanning electron microscopy (SEM) and optical microscopy have been used for thickness measurements. The adhesive properties of elastomer films depend strongly on the film thickness, the Young&#39;s modulus of the polymers and surface characteristics. Therefore, normal adhesion of these films on glass substrates exhibiting smooth and rough surfaces has been investigated. Pull-off stress and work of separation are dependent on the mixing ratio of silicone elastomers.
Additionally, the thickness of the soft skin adhesive placed on top of a supportive backing layer has been varied in order to produce patches for skin applications. Cytotoxicity, proliferation and cellular adhesion of L929 murine fibroblasts on PDMS films (mixing ratio 10:1) and SSA films (mixing ratio 50:50) have been conducted. We have shown here, for the first time, the side by side comparison of thin composite films manufactured of both polymers and present the investigation of their biological- and adhesive properties.

Watch this Scientific Journal Video about Thin Film Composite Silicon Elastomers for Cell Culture and Skin Applications: Manufacturing and Characterization at JoVE.com

Thin Film Composite Silicon Elastomers for Cell Culture and Skin Applications: Manufacturing and Characterization

A protocol for the manufacturing process of polymeric thin film composite structures possessing either different Young&#39;s moduli or thicknesses is presented. Films are produced for advanced cell culture studies or as skin adhesives.

In this protocol, we present methods to fabricate thin elastomer composite films for advanced cell culture applications and for the development of skin ...

thin-film-composite-silicon-elastomers-for-cell-culture-skin

Nanyang Technological University

Research

JoVE Journal

Developmental Biology

10.6K Views.  INM - Leibniz Institute for New Materials. A protocol for the manufacturing process of polymeric thin film composite structures possessing either different Young's moduli or thicknesses is presented. Films are produced for advanced cell culture studies or as skin adhesives.

Video: Thin Film Composite Silicon Elastomers for Cell Culture and Skin Applications: Manufacturing and Characterization

Microfabricated Platforms for Mechanically Dynamic Cell Culture

The ability to systematically probe in vitro cellular response to combinations of mechanobiological stimuli for tissue engineering, drug discovery or fundamental cell biology studies is limited by current bioreactor technologies, which cannot simultaneously apply a variety of mechanical stimuli to cultured cells. In order to address this issue, we have developed a series of microfabricated platforms designed to screen for the effects of mechanical stimuli in a high-throughput format. In this protocol, we demonstrate the fabrication of a microactuator array of vertically displaced posts on which the technology is based, and further demonstrate how this base technology can be modified to conduct high-throughput mechanically dynamic cell culture in both two-dimensional and three-dimensional culture paradigms.

In this protocol, we demonstrate the fabrication of a microactuator array of vertically displaced posts on which the technology is based, and how this base technology can be modified to conduct high-throughput mechanically dynamic cell culture in both two-dimensional and three-dimensional culture paradigms.

The ability to systematically probe in vitro cellular response to combinations of mechanobiological stimuli for tissue engineering, drug discovery or ...

Bioengineering

Directed Cellular Self-Assembly to Fabricate Cell-Derived Tissue Rings for Biomechanical Analysis and Tissue Engineering

Each year, hundreds of thousands of patients undergo coronary artery bypass surgery in the United States.1 Approximately one third of these patients do not have suitable autologous donor vessels due to disease progression or previous harvest. The aim of vascular tissue engineering is to develop a suitable alternative source for these bypass grafts. In addition, engineered vascular tissue may prove valuable as living vascular models to study cardiovascular diseases. Several promising approaches to engineering blood vessels have been explored, with many recent studies focusing on development and analysis of cell-based methods.2-5 Herein, we present a method to rapidly self-assemble cells into 3D tissue rings that can be used in vitro to model vascular tissues.
To do this, suspensions of smooth muscle cells are seeded into round-bottomed annular agarose wells. The non-adhesive properties of the agarose allow the cells to settle, aggregate and contract around a post at the center of the well to form a cohesive tissue ring.6,7 These rings can be cultured for several days prior to harvesting for mechanical, physiological, biochemical, or histological analysis. We have shown that these cell-derived tissue rings yield at 100-500 kPa ultimate tensile strength8 which exceeds the value reported for other tissue engineered vascular constructs cultured for similar durations (&lt;30 kPa).9,10 Our results demonstrate that robust cell-derived vascular tissue ring generation can be achieved within a short time period, and offers the opportunity for direct and quantitative assessment of the contributions of cells and cell-derived matrix (CDM) to vascular tissue structure and function.

This article outlines a versatile method to create cell-derived tissue rings by cellular self-assembly. Smooth muscle cells seeded into ring-shaped agarose wells aggregate and contract to form robust three-dimensional (3D) tissues within 7 days. Millimeter-scale tissue rings are conducive to mechanical testing and serve as building blocks for tissue assembly.

Each year, hundreds of thousands of patients undergo coronary artery bypass surgery in the United States.1 Approximately one third of these patients do ...

Silk Film Culture System for in vitro Analysis and Biomaterial Design

Silk films are promising protein-based biomaterials that can be fabricated with high fidelity and economically within a research laboratory environment 1,2 . These materials are desirable because they possess highly controllable dimensional and material characteristics, are biocompatible and promote cell adhesion, can be modified through topographic patterning or by chemically altering the surface, and can be used as a depot for biologically active molecules for drug delivery related applications 3-8 . In addition, silk films are relatively straightforward to custom design, can be designed to dissolve within minutes or degrade over years in vitro or in vivo, and are produce with the added benefit of being transparent in nature and therefore highly suitable for imaging applications 9-13. The culture system methodology presented here represents a scalable approach for rapid assessments of cell-silk film surface interactions. Of particular interest is the use of surface patterned silk films to study differences in cell proliferation and responses of cells for alignment 12,14 . The seeded cultures were cultured on both micro-patterned and flat silk film substrates, and then assessed through time-lapse phase-contrast imaging, scanning electron microscopy, and biochemical assessment of metabolic activity and nucleic acid content. In summary, the silk film in vitro culture system offers a customizable experimental setup suitable to the study of cell-surface interactions on a biomaterial substrate, which can then be optimized and then translated to in vivo models. Observations using the culture system presented here are currently being used to aid in applications ranging from basic cell interactions to medical device design, and thus are relevant to a broad range of biomedical fields.

Silk Film Culture System for in vitro Analysis and Biomaterial Design

Silk films are a novel class of biomaterials readily customizable for an array of biomedical applications. The presented silk film culture system is highly adaptable to a variety of in vitro analyses. This system represents a biomaterial design platform offering in vitro optimization before direct translation to in vivo models.

Silk films are promising protein-based biomaterials that can be fabricated with high fidelity and economically within a research laboratory environment ...

Silicon Microchips for Manipulating Cell-cell Interaction

The role of the cellular microenvironment is recognized as crucial in determining cell fate and function in virtually all mammalian tissues from development to malignant transformation.&nbsp; In particular, interaction with neighboring stroma has been implicated in a plethora of biological phenomena; however, conventional techniques limit the ability to interrogate the spatial and dynamic elements of such interactions.
In Micromechanical Reconfigurable Culture (RC), we employ a micromachined silicon substrate with moving parts to dynamically control cell-cell interactions through mechanical repositioning. Previously, this method has been applied to investigate intercellular communication in co-cultures of hepatocytes and non-parenchymal cells, demonstrating time-dependent interactions and a limited range for soluble signaling 1.
Here, we describe in detail the preparation and use of the RC system. We begin by demonstrating the handling of the device parts using tweezers, including actuating between the gap and contact configurations (cell populations separated by a narrow 80-&micro;m gap, or in direct intimate contact). Next, we detail the process of preparing the substrates for culture, and the multi-step cell seeding process required for obtaining confluent cell monolayers. Using live microscopy, we then illustrate real-time manipulation of cells between the different possible experimental configurations. Finally, we demonstrate the steps required in order to regenerate the device surface for reuse: toluene and piranha cleaning, polystyrene coating, and oxygen plasma treatment.

This article describes an experimental approach for dynamic regulation of cell-cell interactions between adherent cells on a micrometer scale. Manipulation of intercellular communication between hepatocytes and stromal cell is demonstrated. The developed platform enables investigation of cell-cell interactions in a variety of biological processes, including development and pathogenesis.

The role of the cellular microenvironment is recognized as crucial in determining cell fate and function in virtually all mammalian tissues from ...

Biology

Study of Cell Migration in Microfabricated Channels

The method described here allows the study of cell migration under confinement in one dimension. It is based on the use of microfabricated channels, which impose a polarized phenotype to cells by physical constraints. Once inside channels, cells have only two possibilities: move forward or backward. This simplified migration in which directionality is restricted facilitates the automatic tracking of cells and the extraction of quantitative parameters to describe cell movement. These parameters include cell velocity, changes in direction, and pauses during motion. Microchannels are also compatible with the use of fluorescent markers and are therefore suitable to study localization of intracellular organelles and structures during cell migration at high resolution. Finally, the surface of the channels can be functionalized with different substrates, allowing the control of the adhesive properties of the channels or the study of haptotaxis. In summary, the system here described is intended to analyze the migration of large cell numbers in conditions in which both the geometry and the biochemical nature of the environment are controlled, facilitating the normalization and reproducibility of independent experiments.

A quantitative method to study spontaneous migration of cells in a one-dimensional confined microenvironment is described. This method takes advantage of microfabricated channels and can be used to study migration of large number of cells under different conditions in single experiments.

The method described here allows the study of cell migration under confinement in one dimension. It is based on the use of microfabricated channels, which ...

Stretching Micropatterned Cells on a PDMS Membrane

Mechanical forces exerted on cells and/or tissues play a major role in numerous processes. We have developed a device to stretch cells plated on a PolyDiMethylSiloxane (PDMS) membrane, compatible with imaging. This technique is reproducible and versatile. The PDMS membrane can be micropatterned in order to confine cells or tissues to a specific geometry. The first step is to print micropatterns onto the PDMS membrane with a deep UV technique. The PDMS membrane is then mounted on a mechanical stretcher. A chamber is bound on top of the membrane with biocompatible grease to allow gliding during the stretch. The cells are seeded and allowed to spread for several hours on the micropatterns. The sample can be stretched and unstretched multiple times with the use of a micrometric screw. It takes less than a minute to apply the stretch to its full extent (around 30%). The technique presented here does not include a motorized device, which is necessary for applying repeated stretch cycles quickly and/or computer controlled stretching, but this can be implemented. Stretching of cells or tissue can be of interest for questions related to cell forces, cell response to mechanical stress or tissue morphogenesis. This video presentation will show how to avoid typical problems that might arise when doing this type of seemingly simple experiment.

This manuscript presents a technique to apply or release forces on adherent cells or tissues using unidirectional stretching.

Mechanical forces exerted on cells and/or tissues  play a major role in numerous processes. We have developed a device to stretch  cells plated on a ...

Fabrication and Characterization of a Conformal Skin-like Electronic System for Quantitative, Cutaneous Wound Management

Recent advances in the development of electronic technologies and biomedical devices offer opportunities for non-invasive, quantitative assessment of cutaneous wound healing on the skin. Existing methods, however, still rely on visual inspections through various microscopic tools and devices that normally include high-cost, sophisticated systems and require well trained personnel for operation and data analysis. Here, we describe methods and protocols to fabricate a conformal, skin-like electronics system that enables conformal lamination to the skin surface near the wound tissues, which provides recording of high fidelity electrical signals such as skin temperature and thermal conductivity. The methods of device fabrication provide details of step-by-step preparation of the microelectronic system that is completely enclosed with elastomeric silicone materials to offer electrical isolation. The experimental study presents multifunctional, biocompatible, waterproof, reusable, and flexible/stretchable characteristics of the device for clinical applications. Protocols of clinical testing provide an overview and sequential process of cleaning, testing setup, system operation, and data acquisition with the skin-like electronics, gently mounted on hypersensitive, cutaneous wound and contralateral tissues on patients.

This article presents methods to fabricate and characterize a conformal, skin-like electronic system and protocols for the use in clinical applications, particularly on cutaneous wound management.

Recent advances in the development of electronic technologies and biomedical devices offer opportunities for non-invasive, quantitative assessment of ...

Synthesis of Biocompatible Liquid Crystal Elastomer Foams as Cell Scaffolds for 3D Spatial Cell Cultures

Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block co-polymers featuring cholesterol units as side-chain pendant groups, resulting in smectic-A (SmA) liquid crystal elastomers (LCEs). Foam-like scaffolds, prepared using metal templates, feature interconnected microchannels, making them suitable as 3D cell culture scaffolds. The combined properties of the regular structure of the metal foam and of the elastomer result in a 3D cell scaffold that promotes not only higher cell proliferation compared to conventional porous templated films, but also better management of mass transport (i.e., nutrients, gases, waste, etc.). The nature of the metal template allows for the easy manipulation of foam shapes (i.e., rolls or films) and for the preparation of scaffolds of different pore sizes for different cell studies while preserving the interconnected porous nature of the template. The etching process does not affect the chemistry of the elastomers, preserving their biocompatible and biodegradable nature. We show that these smectic LCEs, when grown for extensive time periods, enable the study of clinically relevant and complex tissue constructs while promoting the growth and proliferation of cells.

This study presents a methodology to prepare 3D, biodegradable, foam-like cell scaffolds based on biocompatible side-chain liquid crystal elastomers (LCEs). Confocal microscopy experiments show that foam-like LCEs allow for cell attachment, proliferation, and the spontaneous alignment of C2C12s myoblasts.

Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block ...

Ultrathin Porated Elastic Hydrogels As a Biomimetic Basement Membrane for Dual Cell Culture

The basement membrane is a critical component of cellular bilayers that can vary in stiffness, composition, architecture, and porosity. In vitro studies of endothelial-epithelial bilayers have traditionally relied on permeable support models that enable bilayer culture, but permeable supports are limited in their ability to replicate the diversity of human basement membranes. In contrast, hydrogel models that require chemical synthesis are highly tunable and allow for modifications of both the material stiffness and the biochemical composition via incorporation of biomimetic peptides or proteins. However, traditional hydrogel models are limited in functionality because they lack pores for cell-cell contacts and functional in vitro migration studies. Additionally, due to the thickness of traditional hydrogels, incorporation of pores that span the entire thickness of hydrogels has been challenging. In the present study, we use poly-(ethylene-glycol) (PEG) hydrogels and a novel zinc oxide templating method to address the previous shortcomings of biomimetic hydrogels. As a result, we present an ultrathin, basement membrane-like hydrogel that permits the culture of confluent cellular bilayers on a customizable scaffold with variable pore architectures, mechanical properties, and biochemical composition.

Current bilayer culture models do not allow for functional in vitro studies that mimic in vivo microenvironments. Using polyethylene glycol and a zinc oxide templating method, this protocol describes the development of an ultrathin biomimetic basement membrane with tunable stiffness, porosity, and biochemical composition that closely mimics in vivo extracellular matrices.

The basement membrane is a critical component of cellular bilayers that can vary in stiffness, composition, architecture, and porosity. In vitro studies ...

Generation of a Simplified Three-Dimensional Skin-on-a-chip Model in a Micromachined Microfluidic Platform

This work presents a new, cost-effective, and reliable microfluidic platform with the potential to generate complex multilayered tissues. As a proof of concept, a simplified and undifferentiated human skin containing a dermal (stromal) and an epidermal (epithelial) compartment has been modelled. To accomplish this, a versatile and robust, vinyl-based device divided into two chambers has been developed, overcoming some of the drawbacks present in microfluidic devices based on polydimethylsiloxane (PDMS) for biomedical applications, such as the use of expensive and specialized equipment or the absorption of small, hydrophobic molecules and proteins. Moreover, a new method based on parallel flow was developed, enabling the in situ deposition of both the dermal and epidermal compartments. The skin construct consists of a fibrin matrix containing human primary fibroblasts and a monolayer of immortalized keratinocytes seeded on top, which is subsequently maintained under dynamic culture conditions. This new microfluidic platform opens the possibility to model human skin diseases and extrapolate the method to generate other complex tissues.

Here, we present a protocol to generate a three-dimensional simplified and undifferentiated skin model using a micromachined microfluidic platform. A parallel flow approach allows the in situ deposition of a dermal compartment for the seeding of epithelial cells on top, all controlled by syringe pumps.

This work presents a new, cost-effective, and reliable microfluidic platform with the potential to generate complex multilayered tissues. As a proof of ...

Thin Film Composite Silicon Elastomers for Cell Culture and Skin Applications: Manufacturing and Characterization

Summary

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Chapters in this video

Microfabricated Platforms for Mechanically Dynamic Cell Culture

Directed Cellular Self-Assembly to Fabricate Cell-Derived Tissue Rings for Biomechanical Analysis and Tissue Engineering

Silk Film Culture System for in vitro Analysis and Biomaterial Design

Silicon Microchips for Manipulating Cell-cell Interaction

Study of Cell Migration in Microfabricated Channels

Stretching Micropatterned Cells on a PDMS Membrane

Fabrication and Characterization of a Conformal Skin-like Electronic System for Quantitative, Cutaneous Wound Management

Synthesis of Biocompatible Liquid Crystal Elastomer Foams as Cell Scaffolds for 3D Spatial Cell Cultures

Ultrathin Porated Elastic Hydrogels As a Biomimetic Basement Membrane for Dual Cell Culture

Generation of a Simplified Three-Dimensional Skin-on-a-chip Model in a Micromachined Microfluidic Platform