Modular Assembly Approach to Engineer Geometrically Precise Cardiovascular Tissue

This modular assembly approach to microfabricate functional cardiovascular tissue composites enables quantitative assessment of the effects of microarchitecture on cellular function. Cardiac and endothelial modules are micromolded separately, designed to direct cardiomyocyte alignment and anisotropic contraction or vascular network formation. Assembled cardiovascular tissue composites contract synchronously, facilitating the use of this tissue-engineering platform to study structure-function relationships in the heart.

Intracellular calcium and cyclic nucleotide levels modulate neurite guidance by microtopographical substrate features

Micro- and nanoscale surface features have emerged as potential tools to direct neurite growth into close proximity with next generation neural prosthesis electrodes. However, the signaling events underlying the ability of growth cones to respond to topographical features remain largely unknown. Accordingly, this study probes the influence of [Ca(2+) ]i and cyclic nucleotide levels on the ability of neurites from spiral ganglion neurons (SGNs) to precisely track topographical micropatterns. Photopolymerization and photomasking were used to generate micropatterned methacrylate polymer substrates. Dissociated SGN cultures were plated on the micropatterned surfaces. Calcium influx and release from internal stores were manipulated by elevating extracellular K(+) , maintenance in calcium-free media, or bath application of various calcium channel blockers. Cyclic nucleotide activity was increased by application of cpt-cAMP or 8-Br-cGMP. Elevation of [Ca(2+) ]i by treatment of cultures with elevated potassium reduced neurite alignment to physical microfeatures. Maintenance of cultures in Ca(2+) -free medium or treatment with the non-selective voltage-gated calcium channel blocker cadmium or L-type Ca(2+) channel blocker nifedipine did not signficantly alter SGN neurite alignment. By contrast, ryanodine or xestospongin C, which block release of internal calcium stores via ryanodine-sensitive channels or inositol-1,4,5-trisphosphate receptors respectively, each significantly decreased neurite alignment. Cpt-cAMP significantly reduced neurite alignment while 8-Br-cGMP significantly enhanced neurite alignment. Manipulation of [Ca(2+) ]i or cAMP levels significantly disrupts neurite guidance while elevation of cGMP levels increases neurite alignment. The results suggest intracellular signaling pathways similar to those recruited by chemotactic cues are involved in neurite guidance by topographical features. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2037-2048, 2016.

Time-Resolved Study of Nanoparticle Induced Apoptosis Using Microfabricated Single Cell Arrays

Cell fate decisions like apoptosis are heterogeneously implemented within a cell population and, consequently, the population response is recognized as sum of many individual dynamic events. Here, we report on the use of micro-patterned single-cell arrays for real-time tracking of nanoparticle-induced (NP) cell death in sets of thousands of cells in parallel. Annexin (pSIVA) and propidium iodide (PI), two fluorescent indicators of apoptosis, are simultaneously monitored after exposure to functionalized polystyrene (PS - NH 2) nanobeads as a model system. We find that the distribution of Annexin onset times shifts to later times and broadens as a function of decreasing NP dose. We discuss the mean time-to-death as a function of dose, and show how the EC 50 value depends both on dose and time of measurement. In addition, the correlations between the early and late apoptotic markers indicate a systematic shift from apoptotic towards necrotic cell death during the course of the experiment. Thus, our work demonstrates the potential of array-based single cell cytometry for kinetic analysis of signaling cascades in a high-throughput format.

Chromosome misalignments induce spindle-positioning defects

Cortical pulling forces on astral microtubules are essential to position the spindle. These forces are generated by cortical dynein, a minus-end directed motor. Previously, another dynein regulator termed Spindly was proposed to regulate dynein-dependent spindle positioning. However, the mechanism of how Spindly regulates spindle positioning has remained elusive. Here, we find that the misalignment of chromosomes caused by Spindly depletion is directly provoking spindle misorientation. Chromosome misalignments induced by CLIP-170 or CENP-E depletion or by noscapine treatment are similarly accompanied by severe spindle-positioning defects. We find that cortical LGN is actively displaced from the cortex when misaligned chromosomes are in close proximity. Preventing the KT recruitment of Plk1 by the depletion of PBIP1 rescues cortical LGN enrichment near misaligned chromosomes and re-establishes proper spindle orientation. Hence, KT-enriched Plk1 is responsible for the negative regulation of cortical LGN localization. In summary, we uncovered a compelling molecular link between chromosome alignment and spindle orientation defects, both of which are implicated in tumorigenesis.

Integration of 3D Printed and Micropatterned Polycaprolactone Scaffolds for Guidance of Oriented Collagenous Tissue Formation In Vivo

Scaffold design incorporating multiscale cues for clinically relevant, aligned tissue regeneration has potential to improve structural and functional integrity of multitissue interfaces. The objective of this preclinical study is to develop poly(ε-caprolactone) (PCL) scaffolds with mesoscale and microscale architectural cues specific to human ligament progenitor cells and assess their ability to form aligned bone-ligament-cementum complexes in vivo. PCL scaffolds are designed to integrate a 3D printed bone region with a micropatterned PCL thin film consisting of grooved pillars. The patterned film region is seeded with human ligament cells, fibroblasts transduced with bone morphogenetic protein-7 genes seeded within the bone region, and a tooth dentin segment positioned on the ligament region prior to subcutaneous implantation into a murine model. Results indicate increased tissue alignment in vivo using micropatterned PCL films, compared to random-porous PCL. At week 6, 30 μm groove depth significantly enhances oriented collagen fiber thickness, overall cell alignment, and nuclear elongation relative to 10 μm groove depth. This study demonstrates for the first time that scaffolds with combined hierarchical mesoscale and microscale features can align cells in vivo for oral tissue repair with potential for improving the regenerative response of other bone-ligament complexes.

Front-Rear Polarization by Mechanical Cues: From Single Cells to Tissues

Directed cell migration is a complex process that involves front-rear polarization, characterized by cell adhesion and cytoskeleton-based protrusion, retraction, and contraction of either a single cell or a cell collective. Single cell polarization depends on a variety of mechanochemical signals including external adhesive cues, substrate stiffness, and confinement. In cell ensembles, coordinated polarization of migrating tissues results not only from the application of traction forces on the extracellular matrix but also from the transmission of mechanical stress through intercellular junctions. We focus here on the impact of mechanical cues on the establishment and maintenance of front-rear polarization from single cell to collective cell behaviors through local or large-scale mechanisms.

Bridging the Gap: From 2D Cell Culture to 3D Microengineered Extracellular Matrices

Historically the culture of mammalian cells in the laboratory has been performed on planar substrates with media cocktails that are optimized to maintain phenotype. However, it is becoming increasingly clear that much of biology discerned from 2D studies does not translate well to the 3D microenvironment. Over the last several decades, 2D and 3D microengineering approaches have been developed that better recapitulate the complex architecture and properties of in vivo tissue. Inspired by the infrastructure of the microelectronics industry, lithographic patterning approaches have taken center stage because of the ease in which cell-sized features can be engineered on surfaces and within a broad range of biocompatible materials. Patterning and templating techniques enable precise control over extracellular matrix properties including: composition, mechanics, geometry, cell-cell contact, and diffusion. In this review article we explore how the field of engineered extracellular matrices has evolved with the development of new hydrogel chemistry and the maturation of micro- and nano- fabrication. Guided by the spatiotemporal regulation of cell state in developing tissues, techniques for micropatterning in 2D, pseudo-3D systems, and patterning within 3D hydrogels will be discussed in the context of translating the information gained from 2D systems to synthetic engineered 3D tissues.

Multi-Stacked Supported Lipid Bilayer Micropatterning through Polymer Stencil Lift-Off

Complex multi-lamellar structures play a critical role in biological systems, where they are present as lamellar bodies, and as part of biological assemblies that control energy transduction processes. Multi-lamellar lipid layers not only provide interesting systems for fundamental research on membrane structure and bilayer-associated polypeptides, but can also serve as components in bioinspired materials or devices. Although the ability to pattern stacked lipid bilayers at the micron scale is of importance for these purposes, limited work has been done in developing such patterning techniques. Here, we present a simple and direct approach to pattern stacked supported lipid bilayers (SLBs) using polymer stencil lift-off and the electrostatic interactions between cationic and anionic lipids. Both homogeneous and phase-segregated stacked SLB patterns were produced, demonstrating that the stacked lipid bilayers retain lateral diffusivity. We demonstrate patterned SLB stacks of up to four bilayers, where fluorescence resonance energy transfer (FRET) and quenching was used to probe the interactions between lipid bilayers. Furthermore, the study of lipid phase behaviour showed that gel phase domains align between adjacent layers. The proposed stacked SLB pattern platform provides a robust model for studying lipid behaviour with a controlled number of bilayers, and an attractive means towards building functional bioinspired materials or devices.

Highly Ordered 1D Fullerene Crystals for Concurrent Control of Macroscopic Cellular Orientation and Differentiation toward Large-Scale Tissue Engineering

A highly aligned 1D fullerene whisker (FW) scaffold in a centimeter area is fabricated by interfacial alignment. The resulting aligned FW scaffold enables concurrent control over cellular orientation and differentiation to muscle cells. This aligned FW scaffold is made by a facile method, and hence the substrate is a promising alternative to other cell scaffolds for tissue engineering.

Role of Cytoskeletal Tension in the Induction of Cardiomyogenic Differentiation in Micropatterned Human Mesenchymal Stem Cell

The role of biophysical induction methods such as cell micropatterning in stem cell differentiation has been well documented previously. However, the underlying mechanistic linkage of the engineered cell shape to directed lineage commitment remains poorly understood. Here, it is reported that micropatterning plays an important role in regulating the optimal cytoskeletal tension development in human mesenchymal stem cell (hMSC) via cell mechanotransduction pathways to induce cardiomyogenic differentiation. Cells are grown on fibronectin strip patterns to control cell polarization and morphology. These patterned cells eventually show directed commitment toward the myocardial lineage. The cell's mechanical properties (cell stiffness and cell traction forces) are observed to be very different for cells that have committed to the myocardial lineage when compared with that of control. These committed cells have mechanical properties that are significantly lower indicating a correlation between the micropatterning-induced differentiation and actomyosin-generated cytoskeletal tension within patterned cells. To study this correlation, patterned cells are treated with RhoA pathway inhibitor. Severely down-regulated cardiomyogenic marker expression is observed in those treated patterned cells, thus emphasizing the direct dependence of hMSCs differentiation fate on the cytoskeletal tension.

Adhesion of adipose-derived mesenchymal stem cells to glycosaminoglycan surfaces with different protein patterns

Proteins and glycosaminoglycans (GAGs) are the main constituents of the extracellular matrix (ECM). They act in synergism and are equally critical for the development, growth, function, or survival of an organism. In this work, we developed surfaces that display these two classes of biomacromolecules, namely, GAGs and proteins, in a spatially controlled fashion. The generated surfaces can be used as a minimalistic but straightforward model aiding the elucidation of cell-ECM interactions. GAGs (hyaluronic acid and heparin) were covalently bound to amino functionalized surfaces, and albumin or fibronectin was patterned by microcontact printing on top of them. We demonstrate that adipose-derived stem cells (ASCs) can adhere either on the protein or on the GAG pattern as a function of the patterned molecules. ASCs found on the GAG pattern had different morphology and expressed different surface markers than the cells adhered on the protein pattern. ASCs morphology and spreading were also dependent on the size of the pattern. These results show that the developed supports can also be used for ASCs differentiation into different lineages.

Prediction of Drug-Induced Liver Injury in Micropatterned Co-cultures Containing iPSC-Derived Human Hepatocytes

Primary human hepatocytes (PHHs) are a limited resource for drug screening, their quality for in vitro use can vary considerably across different lots, and a lack of available donor diversity restricts our understanding of how human genetics affect drug-induced liver injury (DILI). Induced pluripotent stem cell-derived human hepatocyte-like cells (iPSC-HHs) could provide a complementary tool to PHHs for high-throughput drug screening, and ultimately enable personalized medicine. Here, we hypothesized that previously developed iPSC-HH-based micropatterned co-cultures (iMPCCs) with murine embryonic fibroblasts could be amenable to long-term drug toxicity assessment. iMPCCs, created in industry-standard 96-well plates, were treated for 6 days with a set of 47 drugs, and multiple functional endpoints (albumin, urea, ATP) were evaluated in dosed cultures against vehicle-only controls to enable binary toxicity decisions. We found that iMPCCs correctly classified 24 of 37 hepatotoxic drugs (65% sensitivity), while all 10 non-toxic drugs tested were classified as such in iMPCCs (100% specificity). On the other hand, conventional confluent cultures of iPSC-HHs failed to detect several liver toxins that were picked up in iMPCCs. Results for DILI detection in iMPCCs were remarkably similar to published data in PHH-MPCCs (65% versus 70% sensitivity) that were dosed with the same drugs. Furthermore, iMPCCs detected the relative hepatotoxicity of structural drug analogs and recapitulated known mechanisms of acetaminophen toxicity in vitro. In conclusion, iMPCCs could provide a robust tool to screen for DILI potential of large compound libraries in early stages of drug development using an abundant supply of commercially available iPSC-HHs.

Analysis of insulin receptor substrate signaling dynamics on microstructured surfaces

Insulin receptor substrates (IRS) are phosphorylated by activated insulin/insulin-like growth factor I receptor tyrosine kinases, with this comprising an initial key event for downstream signaling and bioactivities. Despite the structural similarities, increasing evidence shows that IRS family proteins have nonredundant functions. Although the specificity of insulin/insulin-like growth factor signaling and biological responses partly reflects which IRS proteins are dominantly phosphorylated by the receptors, the precise properties of the respective IRS interaction with the receptors remain elusive. In the present study, we utilized a technique that combines micropatterned surfaces and total internal reflection fluorescence microscopy for the quantitative analysis of the interaction between IRS proteins and insulin/insulin-like growth factor in living cells. Our experimental set-up enabled the measurement of equilibrium associations and interaction dynamics of these molecules with high specificity. We revealed that several domains of IRS including pleckstrin homology and phosphotyrosine binding domains critically determine the turnover rate of the receptors. Furthermore, we found significant differences among IRS proteins in the strength and kinetic stability of the interaction with the receptors, suggesting that these interaction properties could account for the diverse functions of IRS. In addition, our analyses using fluorescent recovery after photobleaching revealed that kinases such as c-Jun N-terminal kinase and IκB kinase β, which phosphorylate serine/threonine residues of IRS and contribute to insulin resistance, altered the interaction kinetics of IRS with insulin receptor. Collectively, our experimental set-up is a valuable system for quantitifying the physiological interaction of IRS with the receptors in insulin/insulin-like growth factor signaling.

Micropattern size-dependent endothelial differentiation from a human induced pluripotent stem cell line

The multifaceted extracellular milieu presents biochemical and biophysical stimuli that influence stem cell differentiation. Two-dimensional (2D) micropatterned substrates allow the presentation of these cues in spatially defined geometries that have been demonstrated to guide stem cell fate decisions. Leveraging stem cells to reconstruct microvasculature, made up of an inner lining of endothelial cells (ECs) supported by pericytes, is critical to tissue-engineering advances; thus, methods to improve endothelial differentiation efficiency are vital to these efforts. In this study, we examine the hypothesis that the diameter of micropatterned islands influences endothelial differentiation from human induced pluripotent stem cells (hiPSCs). Comparing island diameters of 80, 140, 225 and 500 µm, we found that co-cultures of control ECs and pericytes did not yield variable ratios of cell types; however, when hiPSCs were differentiated toward a bicellular population of ECs and pericytes on these varying micropattern feature sizes, we found that smaller islands promoted EC differentiation efficiency, yielding a derived population composed of 70% ECs, which exhibited a greater sprouting propensity. Differentiation on the largest feature size exhibited a smaller EC yield, similar to that on non-patterned substrates. Taken together, these data demonstrate that micropatterned islands of varying diameters can be used to modulate EC differentiation efficiency. Copyright © 2015 John Wiley & Sons, Ltd.

Activated-ester-type photocleavable crosslinker for preparation of photodegradable hydrogels using a two-component mixing reaction

Photodegradable hydrogels have emerged as powerful platforms for studying and directing cellular behavior in a spatiotemporally controlled manner. Photodegradable hydrogels have previously been formed by free radical polymerizations, Michael-type addition reactions, and orthogonal click reactions. Here, an ester-activated photocleavable crosslinker is presented for preparing photodegradable hydrogels by means of a one-step mixing reaction between the crosslinker and a biocompatible polymer containing amino moieties (amino-terminated tetra-arm poly(ethylene glycol) or gelatin). It is demonstrated that photodegradable hydrogels micropatterned by photolithography can be used to culture cells with high viability and proliferation rates. The resulting micropatterned cell-laden structures can potentially be used to create 3D biomaterials for various tissue-engineering applications.

Agarose-assisted micro-contact printing for high-quality biomolecular micro-patterns

Micro-contact printing has been developed to print biomolecules, such as cell adhesive molecules, proteins, or DNAs, on a substrate, which can serve as experimental platforms for investigating biological issues and engineering biosensors. Despite the popularity of this method, it has been technically challenging to use a conventional stamp made of a hydrophobic polydimethoxysilane (PDMS) elastomer that often requires surface treatments to facilitate the inking and stamping of biomolecules. In this work, we proposed a new surface modification method for a PDMS stamp using agarose hydrogel and demonstrated the applications to the design of micro-patterned substrates with biomolecules. By using a simple bench-top dip-coating method with a commercial syringe pump to steadily pull out the stamp from boiled agarose solution, we coated an agarose layer on the stamp. It consequentially enhanced the transferability of ink molecules to the target substrate and the uniformity of printed patterns compared to the traditional methods for treating stamp surface such as surfactant coating and temporary oxidation with air plasma. In addition, this microstamping method was also used to produce patterns of proteins with the preservation of bioactivity, which could guide neuronal growth. Thus, we demonstrated the applicability to the interface designs of biochips and biosensors.

Micropatterning strategies to engineer controlled cell and tissue architecture in vitro

Micropatterning strategies, which enable control over cell and tissue architecture in vitro, have emerged as powerful platforms for modelling tissue microenvironments at different scales and complexities. Here, we provide an overview of popular micropatterning techniques, along with detailed descriptions, to guide new users through the decision making process of which micropatterning procedure to use, and how to best obtain desired tissue patterns. Example techniques and the types of biological observations that can be made are provided from the literature. A focus is placed on microcontact printing to obtain co-cultures of patterned, confluent sheets, and the challenges associated with optimizing this protocol. Many issues associated with microcontact printing, however, are relevant to all micropatterning methodologies. Finally, we briefly discuss challenges in addressing key limitations associated with current micropatterning technologies.

Spatially controlled graphitization of reduced graphene oxide films via a green mechanical approach

An effective approach to fabricate micropatterned reduced graphene oxide sheets is explored on the basis of the pressure-assisted thermal graphitization as a concept of eco-friendly method. The high pressure can considerably reduce the graphitization temperature and substantially accelerate the kinetics of phase transformation of non-crystalline graphene domain, leading to enhance the degree of graphitization.

Molecular etching: a novel methodology for the generation of complex micropatterned growth surfaces for human cellular assays

The extracellular matrix (ECM) is the non-cellular component of all tissues consisting of many different bioactive macromolecules including proteins, proteoglycans, glycoproteins and gradients of growth factors. It is a highly complex and dynamic structure that is subject to constant remodeling in vivo . The ECM not only provides essential structural support for tissues and cell layers but also modulates molecular and biomechanical signaling cues.[1 -4 ] ECM composition is tightly regulated during normal development and hemostasis and varies with tissue type as well as developmental stage. Hearts of different developmental stages have significant differences in ECM composition and elasticity.[5 , 6 ] Dysregulation of the ECM has also been shown to result in human aortic and connective tissue diseases.[7 ] In addition, ECM has been shown to control cell behavior and function through its elasticity, topography, and dimensionality. In vitro , culture surface stiffness has been shown to directly control the lineage commitment of mesenchymal stem cells.[8 , 9 ]

Delineating fibronectin bioadhesive micropatterns by photochemical immobilization of polystyrene and poly(vinylpyrrolidone)

Bioadhesive micropatterns, capable of laterally confining cells to a 2D lattice, have proven effective in simulating the in vivo tissue environment. They reveal fundamental aspects of the role of adhesion in cell mechanics, proliferation, and differentiation. Here we present an approach based on photochemistry for the fabrication of synthetic polymer micropatterns. Perfluorophenyl azide (PFPA), upon deep-UV exposure, forms a reactive nitrene capable of covalently linking to a molecule that is in close proximity. PFPA has been grafted onto a backbone of poly(allyl amine), which readily forms a self-assembled monolayer on silicon wafers or glass. A film of polystyrene was applied by spin-coating, and by laterally confining the UV exposure through a chromium-on-quartz photomask, monolayers of polymers could be immobilized in circular microdomains. Poly(vinylpyrrolidone) (PVP) was attached to the background to form a barrier to nonspecific protein adsorption and cell adhesion. Micropatterns were characterized with high-lateral-resolution time-of-flight secondary ion mass spectrometry (TOF-SIMS), which confirmed the formation of polystyrene domains within a PVP background. Fluorescence-microscopy adsorption assays with rhodamine-labeled bovine serum albumin demonstrated the nonfouling efficiency of PVP and, combined with TOF-SIMS, allowed for a comprehensive characterization of the pattern geometry. The applicability of the micropatterned platform in single-cell assays was tested by culturing two cell types, WM 239 melanoma cells and SaOs-2 osteoblasts, on micropatterned glass, either with or without backfilling of the patterns with fibronectin. It was demonstrated that the platform was efficient in confining cells to the fibronectin-backfilled micropatterns for at least 48 h. PVP is thus proposed as a viable, highly stable alternative to poly(ethylene glycol) for nonfouling applications. Due to the versatility of the nitrene-insertion reaction, the platform could be extended to other polymer pairs or proteins and the surface chemistry adapted to specific applications.

Photodegradable hydrogels for capture, detection, and release of live cells

Cells may be captured and released using a photodegradable hydrogel (photogel) functionalized with antibodies. Photogel substrates were used to first isolate human CD4 or CD8 T-cells from a heterogeneous cell suspension and then to release desired cells or groups of cells by UV-induced photodegradation. Flow cytometry analysis of the retrieved cells revealed approximately 95% purity of CD4 and CD8 T-cells, suggesting that this substrate had excellent specificity. To demonstrate the possibility of sorting cells according to their function, photogel substrates that were functionalized with anti-CD4 and anti-TNF-α antibodies were prepared. Single cells captured and stimulated on such substrates were identified by the fluorescence "halo" after immunofluorescent staining and could be retrieved by site-specific exposure to UV light through a microscope objective. Overall, it was demonstrated that functional photodegradable hydrogels enable the capture, analysis, and sorting of live cells.

Silk protein lithography as a route to fabricate sericin microarchitectures

Photolithographic fabrication via a "silk sericin photoresist" is used to form precise protein microstructures directly and rapidly on a variety of substrates. High-resolution and fidelity architectures in two and three dimensions with line widths down to 1 μm are formed. Photo-crosslinked protein structures provide structural iridescence and guide cell adhesion with precise spatial control.

Combined nano- and micro-scale topographic cues for engineered vascular constructs by electrospinning and imprinted micro-patterns

The major cause of synthetic vessel failure is thrombus and neointima formation. To prevent these problems the creation of a continuous and elongated endothelium inside lumen vascular grafts might be a promising solution for tissue engineering. Different micro- and nano-surface topographic cues including grooved micro-patterns and electrospun fibers have been previously demonstrated to guide the uniform alignment of endothelial cells (ECs). Here, with a very simple and highly versatile approach we combined electrospinning with soft lithography to fabricate nanofibrous scaffolds with oriented fibers modulated by different micro-grooved topographies. The effect of these scaffolds on the behavior of the ECs are analyzed, including their elongation, spreading, proliferation, and functioning using unpatterned random and aligned nanofibers (NFs) as controls. It is demonstrated that both aligned NFs and micro-patterns effectively influence the cellular response, and that a proper combination of topographic parameters, exploiting the synergistic effects of micro-scale and sub-micrometer features, can promote EC elongation, allowing the creation of a confluent ECs monolayer in analogy with the natural endothelium as assessed by the positive expression of vinculin. Combining different micro- and nano-topographic cues by complementary soft patterning and spinning technologies could open interesting perspectives for engineered vascular replacement constructions.

Photo-patterning of non-fouling polymers and biomolecules on paper

Functional cellulose substrates with tetrazole moieties are generated to serve as universal platforms for the spatio-temporal immobilization of synthetic ultra-low fouling polymer brushes and protein species via a nitrile imine-mediated tetrazole-ene cycloaddition (NITEC)-based protocol. Poly(carboxybetaine acrylamide) brushes are grafted from initiators photo-patterned by NITEC utilizing single electron transfer living radical polymerization. Streptavidin is photo-immobilized with remarkable efficiency, opening the possibility to generate new materials for biomedical and biosensing applications.

Hydrogel-mediated direct patterning of conducting polymer films with multiple surface chemistries

A new methodology for selective electropolymerization of conducting polymer films using wet hydrogel stamps is presented. The ability of this simple method to generate patterned films of conducting polymers with multiple surface chemistries in a one-step process and to incorporate fragile biomolecules in these films is demonstrated.