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Gaspard Pardon

Stanford University, Microbiology & Immunology/Baxter Laboratory, Post-Doc

KTH Royal Institute of Technology, Micro and Nanosystems, Post-Doc

Stanford University, Bioengineering, Post-Doc

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My curiosity and enthusiasm drive my desire to understand and innovate!Always trying to connect the smallest details with the big picture, I like to question both the answers and the questions, and to look one step ahead.Exchanging ideas and dreams with friends and colleagues is central to me.As an engineer in micro and nanosystems for biomedical applications, I seek to generate exciting results for the scientific community and to make them useful for society. Coming from the Swiss mountains and after 9 years in Sweden, I currently live in the Bay Area, California, USA. But anywhere I go, I love discovering new summits, valleys, islands and forests, by ski, foot, boat or bicycle, with my camera never very far.

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Hithesh K U M A R Gatty

KTH Royal Institute of Technology

Igor Iatsunskyi

Odessa National I. Mechnikov University

rigardt coetzee

Maria Eugenia Toimil-Molares

Romeo-Cristian Ciobanu

Nancy A Monteiro-Riviere

Kansas State University

Waldemar Marmisollé

Universidad Nacional de La Plata

Boston University

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Papers by Gaspard Pardon

Pt–Al<sub>2</sub>O<sub>3</sub>dual layer atomic layer deposition coating in high aspect ratio nanopores

Nanotechnology, Dec 5, 2012

This is the accepted version of a paper published in Nanotechnology. This paper has been peerrevi... more

Increased tissue stiffness triggers contractile dysfunction and telomere shortening in dystrophic cardiomyocytes

Stem cell reports, Sep 1, 2021

Summary Duchenne muscular dystrophy (DMD) is a rare X-linked recessive disease that is associated... more Summary Duchenne muscular dystrophy (DMD) is a rare X-linked recessive disease that is associated with severe progressive muscle degeneration culminating in death due to cardiorespiratory failure. We previously observed an unexpected proliferation-independent telomere shortening in cardiomyocytes of a DMD mouse model. Here, we provide mechanistic insights using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Using traction force microscopy, we show that DMD hiPSC-CMs exhibit deficits in force generation on fibrotic-like bioengineered hydrogels, aberrant calcium handling, and increased reactive oxygen species levels. Furthermore, we observed a progressive post-mitotic telomere shortening in DMD hiPSC-CMs coincident with downregulation of shelterin complex, telomere capping proteins, and activation of the p53 DNA damage response. This telomere shortening is blocked by blebbistatin, which inhibits contraction in DMD cardiomyocytes. Our studies underscore the role of fibrotic stiffening in the etiology of DMD cardiomyopathy. In addition, our data indicate that telomere shortening is progressive, contraction dependent, and mechanosensitive, and suggest points of therapeutic intervention.

MicrosystemsLab/TFM-model: TFM model v1.0

This is the first release of the TFM model for validation and benchmarking of computational TFM a... more

Abstract 522: Impaired Inside-out Force Transmission in Hipsc-cardiomyocyte Model of Duchenne Muscular Dystrophy Cardiomyopathy

Circulation Research, Jul 31, 2020

Duchenne Muscular Dystrophy (DMD) is a lethal X-chromosome linked disease that affects ~1:3500 bo... more Duchenne Muscular Dystrophy (DMD) is a lethal X-chromosome linked disease that affects ~1:3500 boys and culminates in heart failure in early adulthood. DMD results from &gt;200 possible dystrophin mutations. The lack of dystrophin disrupts the anchoring of the sarcomere to the extracellular matrix (ECM), impairing cardiomyocyte function and cardiac contraction. With disease progression, the heart tissue stiffness increases as fibrosis progresses and a dilated cardiomyopathy phenotype develops. We hypothesize that disease progression accelerates because of a positive feedback loop involving fibrotic stiffening and mechanosensing. Our preliminary results show that single human-derived pluripotent stem cell (hiPSC) cardiomyocytes (CMs) with DMD mutations have a dramatically reduced ability to produce force compared to isogenic controls on stiffer substrates mimicking a fibrotic state, but not on soft healthy substrates. This stiffness-dependent contractile deficiency correlates with an increase in reactive oxygen species (ROS) and mitochondrial dysfunction, as well as other markers of cellular stress response and senescence. Here, we ask how stiffness affects the progression of DMD cardiomyopathy and aim to draw a link between the lack of dystrophin and force production deficiency in hiPSC-CMs with or without DMD mutations in an isogenic background. Using a novel assay and algorithm, we simultaneously measure extracellular force production by traction force microscopy (TFM) and single sarcomere dynamics (SSD) in single hiPSC-CMs adhered onto ECM micropatterns on top of a hydrogel of stiffness matching that of healthy (~10kPa) or fibrotic (~35kPa) tissue. We induce the single hiPSC-CMs to adopt a physiologic elongated 1:7 aspect ratio using microcontact printing of ECM protein. Using this platform, we determine how the lack of dystrophin impacts sarcomere architecture, sarcomere contractility, and force generation in the etiology of DMD cardiac disease.

Insights into single hiPSC-derived cardiomyocyte phenotypes and maturation using ConTraX, an efficient pipeline for tracking contractile dynamics

bioRxiv (Cold Spring Harbor Laboratory), Mar 19, 2021

Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) are powerful in-vitr... more Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) are powerful in-vitro models to study the mechanisms underlying cardiomyopathies and cardiotoxicity. To understand how cellular mechanisms affect the heart, it is crucial to quantify the contractile function in single hiPSC-CMs over time, however, such measurements remain demanding and low-throughput, and are too seldom considered. We developed an open-access, versatile, streamlined, and highly automated pipeline to address these challenges and enable quantitative tracking of the contractile dynamics of single hiPSC-CMs over time: ConTraX. Three interlocking software modules enable: (i) parameterbased localization and selection of single hiPSC-CMs; (ii) automated video acquisition of >200 cells/hour; and (iii) streamlined measurements of the contractile parameters via traction force microscopy. Using ConTraX, we analyzed >2,753 hiPSC-CMs over time under orthogonal experimental conditions in terms of culture media and substrate stiffnesses. Using undirected high-dimensional clustering, we dissected the complex diversity of contractile phenotypes in hiPSC-CM populations and revealed converging maturation patterns. Our modular ConTraX pipeline empowers biologists with a potent quantitative analytic tool applicable to the development of cardiac therapies.

Modeling and simulation of electrostatically gated nanochannels

Advances in Colloid and Interface Science, Nov 1, 2013

A new method that allows for mold-free, rapid and easy-to-use prototyping of microfluidic devices... more A new method that allows for mold-free, rapid and easy-to-use prototyping of microfluidic devices comprising channels, access holes and surface modified patterns, is presented. The innovative method is based on direct photolithographic patterning of an off-stoichiometry thiol-ene (OSTE) polymer formulation, tailor-made for photolithography, which offers unprecedented spatial resolution and allows for efficient, robust and reliable, room temperature surface modification and glue-free, covalent room temperature bonding. This mold-free process does not require cleanroom equipment and therefore allows for rapid, i.e. less than one hour, design-fabricate-test cycles, using a material suited for larger scale production. The excellent photolithographic properties of this new OSTE formulation allow for unprecedented, for thiol-ene polymer systems, resolution patterning in hundreds of micrometers thick layers, 200 µm thick in this work. Moreover, we demonstrated robust (covalent) and spatially-controlled modification of the microchannel surfaces with a contact angle of 76 degrees to hydrophobic/hydrophilic areas with contact angles of 102 and 43 degrees, respectively.

A 3D microfluidic cage collector for airborne particles

We designed, manufactured, and integrated the first 3D microfluidic collector for capturing airbo... more We designed, manufactured, and integrated the first 3D microfluidic collector for capturing airborne particles directly into liquid; using an integrated electrostatic precipitator (ESP) sampler, designed for breath diagnostic purposes. The novel collector increases the sampler's air-to-liquid capture efficiency by 35 times, when compared with previous 2D collectors.

Hypertrophic cardiomyopathy ß-cardiac myosin mutation (P710R) leads to hypercontractility by disrupting super-relaxed state

bioRxiv (Cold Spring Harbor Laboratory), Nov 10, 2020

Author Contributions: AVR performed and analyzed the functional measurements of the hiPSC-CMs (TF... more Author Contributions: AVR performed and analyzed the functional measurements of the hiPSC-CMs (TFM, immunostaining, inhibitor treatment) and performed computational modeling. CL developed techniques and performed and analyzed the HFS and motility measurements. MMM performed and analyzed the 2-hep and 25-hep ATPase and single-turnover measurements. KBK performed the initial gene editing of the cells and assisted with preliminary molecular and cellular measurements. CL, MMM, and DS prepared protein. DS performed preliminary motility measurements. GP wrote the code for analysis of the TFM data. GJ contributed to the quantification of cell hypertrophy. GJ, SR, GF, and MZ assisted with functional measurements of hiPSC-CMs. AJ contributed to the sensitivity analysis and optimization of the modeling results. KSC developed the original computer model and assisted with its adaptation for this project. KMR and AD prepared the transgenic virus. AVR, CL, and MMM wrote the manuscript. BLP, KMR, JAS, and DB contributed to intellectual oversight of the project and writing the manuscript. All authors contributed intellectually to discussions of the results and reviewed and edited the paper. Competing Interest Statement: JAS is co-founder and on the Scientific Advisory Board of Cytokinetics, Inc., a company developing small molecule therapeutics for treatment of hypertrophic cardiomyopathy. DB has also consulted for Cytokinetics, Inc.

Electrostatic gating of ion and molecule transport through a nanochannel-array membrane

This work presents a predictive and today's most complete model for electrostatic gating of nanof... more This work presents a predictive and today's most complete model for electrostatic gating of nanofluidic channels. The model is based on the classical mean field equations and accounts for the surface reactivity. The model is successfully verified against previously published experimental data [1]. The fabrication concept of a novel device is introduced and its predicted performances are discussed with the help of the presented model. A ~40x performance improvement, in terms of tunability of the ionic conductivity in the nanochannel, in comparison to the result presented in [1], is expected.

Surface energy micropattern inheritance from mold to replica

ABSTRACT We report a novel surface-energy patterning phenomenon, in which a novel polymer composi... more ABSTRACT We report a novel surface-energy patterning phenomenon, in which a novel polymer composition inherits the surface energy of the medium it is in contact with during polymerization. This surface property mimicking process occurs via spontaneous selective molecular alignment of hydrophilic and hydrophobic monomers mixed into an off-stoichiometry thiol-ene (OSTE) formulation. This single-step method for simultaneous structuring and surface energy micropatterning of polymer structures is potentially more robust and lower cost than state-of-the-art processes requiring post-processing surface modification steps. We further demonstrate the self-assembly of a liquid droplet array on the replicated polymer surfaces.

The Influence of Air Flow Velocity and Particle Size on the Collection Efficiency of Passive Electrostatic Aerosol Samplers

Aerosol and Air Quality Research, 2019

Electrostatic sampling is a promising method for the collection of bioaerosol particles. Although... more Electrostatic sampling is a promising method for the collection of bioaerosol particles. Although the underlying physics responsible for particle collection are well understood, the collection efficiency of simple passive electrostatic samplers is difficult to predict. Under these conditions, the collection efficiency becomes very sensitive to ambient air current and particle size, especially for submicron particles relevant for airborne virus transmission. In this paper, we compare two electrostatic aerosol sampler designs, a commercial product consisting of a flat collector plate located in the same plane as the charging needles and an axisymmetric design sampling directly to a liquid droplet. The aerosol particle collection efficiency of the samplers is investigated for particle size ranging from 0.25 to 2 µm while the air flow velocity surrounding the samplers is varied from 0.3 to 1 m s-1. For the planar design, at all ambient flow velocities, the submicron fraction of the particles captured originates in streamlines up to a maximum of 75 mm above the surface of the device collector, which greatly limits the volume of air being effectively sampled. The axisymmetric design features a nonmonotonic capture efficiency as a function of particle size, with a minimum between 0.4 and 0.8 µm. The flow field in the inter-electrode region, captured using particle image velocimetry (PIV) reveals the presence of strong recirculation zones that can be responsible for the increased collection efficiency for very small particles.

Aerosol sampling using an electrostatic precipitator integrated with a microfluidic interface

Sensors and Actuators B-chemical, Jun 1, 2015

In this work, the development of a point-of-care (PoC) system to capture aerosol from litres of a... more In this work, the development of a point-of-care (PoC) system to capture aerosol from litres of air directly onto a microfluidic lab-on-chip for subsequent analysis is addressed. The system involves an electrostatic precipitator that uses corona charging and electrophoretic transport to capture aerosol droplets onto a microfluidic air-to-liquid interface for downstream analysis. A theoretical study of the governing geometric and operational parameters for optimal electrostatic precipitation is presented. The fabrication of an electrostatic precipitator prototype and its experimental validation using a laboratory-generated aerosolized dye is described. Collection efficiencies were comparable to those of a state-of-the-art Biosampler impinger, with the significant advantage of providing samples that are at least 10 times more concentrated. Finally, we discuss the potential of such a system for breath-based diagnostics.

Electrostatic Sampling of Patient Breath for Pathogen Detection: A Pilot Study

Frontiers in Mechanical Engineering, Jun 18, 2020

Collecting samples for diagnosis of respiratory infections can be invasive and highly uncomfortab... more Collecting samples for diagnosis of respiratory infections can be invasive and highly uncomfortable for patients; with sampling techniques ranging from nasal or throat swabs to bronchoalveolar lavage. In this work, we explore the electrostatic capture of exhaled pathogens as a non-invasive sampling method for rapid diagnosis in a primary care setting. A pilot study at primary care centers in Belgium enrolled 20 patients presenting with flu-like symptoms whose diagnosis was determined by nasopharyngeal (NP) swabs. We collected exhaled aerosol particles from infected patients using a breath electrostatic sampler (BESS) and using filters, following an extremely light procedure consisting of five normal exhales. All samples were analyzed using a commercial multiplex q-RT-PCR panel assay. Staphylococcus aureus (S. aureus) was detected from BESS samples of seven patients; three of whom were in agreement with their corresponding diagnoses. The BESS method was negative for exhaled viruses. We detected viruses, but no bacteria, with the filters, but the results showed no correlation with the corresponding diagnosis. Our results indicate that electrostatic sampling of exhaled breath is a technique and approach potentially suited for the primary care setting, where it might constitute a helpful diagnostic device.

Engineering hiPSC cardiomyocyte in vitro model systems for functional and structural assessment

Progress in Biophysics & Molecular Biology, Jul 1, 2019

The study of human cardiomyopathies and the development and testing of new therapies has long bee... more The study of human cardiomyopathies and the development and testing of new therapies has long been limited by the availability of appropriate in vitro model systems. Cardiomyocytes are highly specialized cells whose internal structure and contractile function are sensitive to the local microenvironment and the combination of mechanical and biochemical cues they receive. The complementary technologies of human induced pluripotent stem cell (hiPSC) derived cardiomyocytes (CMs) and microphysiological systems (MPS) allow for precise control of the genetics and microenvironment of human cells in in vitro contexts. These combined systems also enable quantitative measurement of mechanical function and intracellular organization. This review describes relevant factors in the myocardium microenvironment that affect CM structure and mechanical function and demonstrates the application of several engineered microphysiological systems for studying development, disease, and drug discovery.

A benchmarking model for validation and standardization of traction force microscopy analysis tools

bioRxiv (Cold Spring Harbor Laboratory), Aug 14, 2020

Traction Force Microscopy (TFM) has become a well-established technique to assay the biophysical ... more Traction Force Microscopy (TFM) has become a well-established technique to assay the biophysical force produced by cells cultured on soft substrates of controlled stiffness. However, experimental conditions as well as computational implementations can have a large impact on the analysis results accuracy and reproducibility. While this can be alleviated using appropriate controls and a rigorous analytical approach, the comparison of results across studies remains difficult and there is a need for validation and benchmarking tools. To validate the accuracy of and compare various computational TFM analysis algorithms, we developed a virtual in silico

Simultaneous Replication of Hydrophilic and Superhydrophobic Micropatterns through Area-Selective Monomers Self-Assembly

Advanced Materials Interfaces, Aug 22, 2016

Simultaneous replication of hydrophilic and superhydrophobic micropatterns through areaselective ... more

A predictive model for electrostatically gated nanofluidic channels

Fabrication of nanochannels by replica molding using off-stoichiometry thiol-ene (OSTE) polymer

Fabrication of nanochannels by replica molding using off-stoichiometry thiol-ene (OSTE) polymer

From Macro to Nano : Electrokinetic Transport and Surface Control

Today, the growing and aging population, and the rise of new global threats on human health puts ... more Today, the growing and aging population, and the rise of new global threats on human health puts an increasing demand on the healthcare system and calls for preventive actions. To make existing medical treatments more efficient and widely accessible and to prevent the emergence of new threats such as drug-resistant bacteria, improved diagnostic technologies are needed. Potential solutions to address these medical challenges could come from the development of novel lab-on-chip (LoC) for point-of-care (PoC) diagnostics. At the same time, the increasing demand for sustainable energy calls for the development of novel approaches for energy conversion and storage systems (ECS), to which micro-and nanotechnologies could also contribute. This thesis has for objective to contribute to these developments and presents the results of interdisciplinary research at the crossing of three disciplines of physics and engineering: electrokinetic transport in fluids, manufacturing of micro-and nanofluidic systems, and surface control and modification. By combining knowledge from each of these disciplines, novel solutions and functionalities were developed at the macro-, micro-and nanoscale, towards applications in PoC diagnostics and ECS systems.

Le Secteur Pavillon et Transports à l’Exposition nationale suisse, Lausanne 1964

Keywords: Esthetique ; Histoire et esthetique de l'image ; Section MT Reference SHS-STUDENT-2... more

Pt–Al<sub>2</sub>O<sub>3</sub>dual layer atomic layer deposition coating in high aspect ratio nanopores

Nanotechnology, Dec 5, 2012

This is the accepted version of a paper published in Nanotechnology. This paper has been peerrevi... more

Increased tissue stiffness triggers contractile dysfunction and telomere shortening in dystrophic cardiomyocytes

Stem cell reports, Sep 1, 2021

Summary Duchenne muscular dystrophy (DMD) is a rare X-linked recessive disease that is associated... more Summary Duchenne muscular dystrophy (DMD) is a rare X-linked recessive disease that is associated with severe progressive muscle degeneration culminating in death due to cardiorespiratory failure. We previously observed an unexpected proliferation-independent telomere shortening in cardiomyocytes of a DMD mouse model. Here, we provide mechanistic insights using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Using traction force microscopy, we show that DMD hiPSC-CMs exhibit deficits in force generation on fibrotic-like bioengineered hydrogels, aberrant calcium handling, and increased reactive oxygen species levels. Furthermore, we observed a progressive post-mitotic telomere shortening in DMD hiPSC-CMs coincident with downregulation of shelterin complex, telomere capping proteins, and activation of the p53 DNA damage response. This telomere shortening is blocked by blebbistatin, which inhibits contraction in DMD cardiomyocytes. Our studies underscore the role of fibrotic stiffening in the etiology of DMD cardiomyopathy. In addition, our data indicate that telomere shortening is progressive, contraction dependent, and mechanosensitive, and suggest points of therapeutic intervention.

MicrosystemsLab/TFM-model: TFM model v1.0

This is the first release of the TFM model for validation and benchmarking of computational TFM a... more

Abstract 522: Impaired Inside-out Force Transmission in Hipsc-cardiomyocyte Model of Duchenne Muscular Dystrophy Cardiomyopathy

Circulation Research, Jul 31, 2020

Duchenne Muscular Dystrophy (DMD) is a lethal X-chromosome linked disease that affects ~1:3500 bo... more Duchenne Muscular Dystrophy (DMD) is a lethal X-chromosome linked disease that affects ~1:3500 boys and culminates in heart failure in early adulthood. DMD results from &gt;200 possible dystrophin mutations. The lack of dystrophin disrupts the anchoring of the sarcomere to the extracellular matrix (ECM), impairing cardiomyocyte function and cardiac contraction. With disease progression, the heart tissue stiffness increases as fibrosis progresses and a dilated cardiomyopathy phenotype develops. We hypothesize that disease progression accelerates because of a positive feedback loop involving fibrotic stiffening and mechanosensing. Our preliminary results show that single human-derived pluripotent stem cell (hiPSC) cardiomyocytes (CMs) with DMD mutations have a dramatically reduced ability to produce force compared to isogenic controls on stiffer substrates mimicking a fibrotic state, but not on soft healthy substrates. This stiffness-dependent contractile deficiency correlates with an increase in reactive oxygen species (ROS) and mitochondrial dysfunction, as well as other markers of cellular stress response and senescence. Here, we ask how stiffness affects the progression of DMD cardiomyopathy and aim to draw a link between the lack of dystrophin and force production deficiency in hiPSC-CMs with or without DMD mutations in an isogenic background. Using a novel assay and algorithm, we simultaneously measure extracellular force production by traction force microscopy (TFM) and single sarcomere dynamics (SSD) in single hiPSC-CMs adhered onto ECM micropatterns on top of a hydrogel of stiffness matching that of healthy (~10kPa) or fibrotic (~35kPa) tissue. We induce the single hiPSC-CMs to adopt a physiologic elongated 1:7 aspect ratio using microcontact printing of ECM protein. Using this platform, we determine how the lack of dystrophin impacts sarcomere architecture, sarcomere contractility, and force generation in the etiology of DMD cardiac disease.

Insights into single hiPSC-derived cardiomyocyte phenotypes and maturation using ConTraX, an efficient pipeline for tracking contractile dynamics

bioRxiv (Cold Spring Harbor Laboratory), Mar 19, 2021

Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) are powerful in-vitr... more Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) are powerful in-vitro models to study the mechanisms underlying cardiomyopathies and cardiotoxicity. To understand how cellular mechanisms affect the heart, it is crucial to quantify the contractile function in single hiPSC-CMs over time, however, such measurements remain demanding and low-throughput, and are too seldom considered. We developed an open-access, versatile, streamlined, and highly automated pipeline to address these challenges and enable quantitative tracking of the contractile dynamics of single hiPSC-CMs over time: ConTraX. Three interlocking software modules enable: (i) parameterbased localization and selection of single hiPSC-CMs; (ii) automated video acquisition of >200 cells/hour; and (iii) streamlined measurements of the contractile parameters via traction force microscopy. Using ConTraX, we analyzed >2,753 hiPSC-CMs over time under orthogonal experimental conditions in terms of culture media and substrate stiffnesses. Using undirected high-dimensional clustering, we dissected the complex diversity of contractile phenotypes in hiPSC-CM populations and revealed converging maturation patterns. Our modular ConTraX pipeline empowers biologists with a potent quantitative analytic tool applicable to the development of cardiac therapies.

Modeling and simulation of electrostatically gated nanochannels

Advances in Colloid and Interface Science, Nov 1, 2013

A new method that allows for mold-free, rapid and easy-to-use prototyping of microfluidic devices... more A new method that allows for mold-free, rapid and easy-to-use prototyping of microfluidic devices comprising channels, access holes and surface modified patterns, is presented. The innovative method is based on direct photolithographic patterning of an off-stoichiometry thiol-ene (OSTE) polymer formulation, tailor-made for photolithography, which offers unprecedented spatial resolution and allows for efficient, robust and reliable, room temperature surface modification and glue-free, covalent room temperature bonding. This mold-free process does not require cleanroom equipment and therefore allows for rapid, i.e. less than one hour, design-fabricate-test cycles, using a material suited for larger scale production. The excellent photolithographic properties of this new OSTE formulation allow for unprecedented, for thiol-ene polymer systems, resolution patterning in hundreds of micrometers thick layers, 200 µm thick in this work. Moreover, we demonstrated robust (covalent) and spatially-controlled modification of the microchannel surfaces with a contact angle of 76 degrees to hydrophobic/hydrophilic areas with contact angles of 102 and 43 degrees, respectively.

A 3D microfluidic cage collector for airborne particles

We designed, manufactured, and integrated the first 3D microfluidic collector for capturing airbo... more We designed, manufactured, and integrated the first 3D microfluidic collector for capturing airborne particles directly into liquid; using an integrated electrostatic precipitator (ESP) sampler, designed for breath diagnostic purposes. The novel collector increases the sampler's air-to-liquid capture efficiency by 35 times, when compared with previous 2D collectors.

Hypertrophic cardiomyopathy ß-cardiac myosin mutation (P710R) leads to hypercontractility by disrupting super-relaxed state

bioRxiv (Cold Spring Harbor Laboratory), Nov 10, 2020

Author Contributions: AVR performed and analyzed the functional measurements of the hiPSC-CMs (TF... more Author Contributions: AVR performed and analyzed the functional measurements of the hiPSC-CMs (TFM, immunostaining, inhibitor treatment) and performed computational modeling. CL developed techniques and performed and analyzed the HFS and motility measurements. MMM performed and analyzed the 2-hep and 25-hep ATPase and single-turnover measurements. KBK performed the initial gene editing of the cells and assisted with preliminary molecular and cellular measurements. CL, MMM, and DS prepared protein. DS performed preliminary motility measurements. GP wrote the code for analysis of the TFM data. GJ contributed to the quantification of cell hypertrophy. GJ, SR, GF, and MZ assisted with functional measurements of hiPSC-CMs. AJ contributed to the sensitivity analysis and optimization of the modeling results. KSC developed the original computer model and assisted with its adaptation for this project. KMR and AD prepared the transgenic virus. AVR, CL, and MMM wrote the manuscript. BLP, KMR, JAS, and DB contributed to intellectual oversight of the project and writing the manuscript. All authors contributed intellectually to discussions of the results and reviewed and edited the paper. Competing Interest Statement: JAS is co-founder and on the Scientific Advisory Board of Cytokinetics, Inc., a company developing small molecule therapeutics for treatment of hypertrophic cardiomyopathy. DB has also consulted for Cytokinetics, Inc.

Electrostatic gating of ion and molecule transport through a nanochannel-array membrane

This work presents a predictive and today's most complete model for electrostatic gating of nanof... more This work presents a predictive and today's most complete model for electrostatic gating of nanofluidic channels. The model is based on the classical mean field equations and accounts for the surface reactivity. The model is successfully verified against previously published experimental data [1]. The fabrication concept of a novel device is introduced and its predicted performances are discussed with the help of the presented model. A ~40x performance improvement, in terms of tunability of the ionic conductivity in the nanochannel, in comparison to the result presented in [1], is expected.

Surface energy micropattern inheritance from mold to replica

ABSTRACT We report a novel surface-energy patterning phenomenon, in which a novel polymer composi... more ABSTRACT We report a novel surface-energy patterning phenomenon, in which a novel polymer composition inherits the surface energy of the medium it is in contact with during polymerization. This surface property mimicking process occurs via spontaneous selective molecular alignment of hydrophilic and hydrophobic monomers mixed into an off-stoichiometry thiol-ene (OSTE) formulation. This single-step method for simultaneous structuring and surface energy micropatterning of polymer structures is potentially more robust and lower cost than state-of-the-art processes requiring post-processing surface modification steps. We further demonstrate the self-assembly of a liquid droplet array on the replicated polymer surfaces.

The Influence of Air Flow Velocity and Particle Size on the Collection Efficiency of Passive Electrostatic Aerosol Samplers

Aerosol and Air Quality Research, 2019

Electrostatic sampling is a promising method for the collection of bioaerosol particles. Although... more Electrostatic sampling is a promising method for the collection of bioaerosol particles. Although the underlying physics responsible for particle collection are well understood, the collection efficiency of simple passive electrostatic samplers is difficult to predict. Under these conditions, the collection efficiency becomes very sensitive to ambient air current and particle size, especially for submicron particles relevant for airborne virus transmission. In this paper, we compare two electrostatic aerosol sampler designs, a commercial product consisting of a flat collector plate located in the same plane as the charging needles and an axisymmetric design sampling directly to a liquid droplet. The aerosol particle collection efficiency of the samplers is investigated for particle size ranging from 0.25 to 2 µm while the air flow velocity surrounding the samplers is varied from 0.3 to 1 m s-1. For the planar design, at all ambient flow velocities, the submicron fraction of the particles captured originates in streamlines up to a maximum of 75 mm above the surface of the device collector, which greatly limits the volume of air being effectively sampled. The axisymmetric design features a nonmonotonic capture efficiency as a function of particle size, with a minimum between 0.4 and 0.8 µm. The flow field in the inter-electrode region, captured using particle image velocimetry (PIV) reveals the presence of strong recirculation zones that can be responsible for the increased collection efficiency for very small particles.

Aerosol sampling using an electrostatic precipitator integrated with a microfluidic interface

Sensors and Actuators B-chemical, Jun 1, 2015

In this work, the development of a point-of-care (PoC) system to capture aerosol from litres of a... more In this work, the development of a point-of-care (PoC) system to capture aerosol from litres of air directly onto a microfluidic lab-on-chip for subsequent analysis is addressed. The system involves an electrostatic precipitator that uses corona charging and electrophoretic transport to capture aerosol droplets onto a microfluidic air-to-liquid interface for downstream analysis. A theoretical study of the governing geometric and operational parameters for optimal electrostatic precipitation is presented. The fabrication of an electrostatic precipitator prototype and its experimental validation using a laboratory-generated aerosolized dye is described. Collection efficiencies were comparable to those of a state-of-the-art Biosampler impinger, with the significant advantage of providing samples that are at least 10 times more concentrated. Finally, we discuss the potential of such a system for breath-based diagnostics.

Electrostatic Sampling of Patient Breath for Pathogen Detection: A Pilot Study

Frontiers in Mechanical Engineering, Jun 18, 2020

Collecting samples for diagnosis of respiratory infections can be invasive and highly uncomfortab... more Collecting samples for diagnosis of respiratory infections can be invasive and highly uncomfortable for patients; with sampling techniques ranging from nasal or throat swabs to bronchoalveolar lavage. In this work, we explore the electrostatic capture of exhaled pathogens as a non-invasive sampling method for rapid diagnosis in a primary care setting. A pilot study at primary care centers in Belgium enrolled 20 patients presenting with flu-like symptoms whose diagnosis was determined by nasopharyngeal (NP) swabs. We collected exhaled aerosol particles from infected patients using a breath electrostatic sampler (BESS) and using filters, following an extremely light procedure consisting of five normal exhales. All samples were analyzed using a commercial multiplex q-RT-PCR panel assay. Staphylococcus aureus (S. aureus) was detected from BESS samples of seven patients; three of whom were in agreement with their corresponding diagnoses. The BESS method was negative for exhaled viruses. We detected viruses, but no bacteria, with the filters, but the results showed no correlation with the corresponding diagnosis. Our results indicate that electrostatic sampling of exhaled breath is a technique and approach potentially suited for the primary care setting, where it might constitute a helpful diagnostic device.

Engineering hiPSC cardiomyocyte in vitro model systems for functional and structural assessment

Progress in Biophysics & Molecular Biology, Jul 1, 2019

The study of human cardiomyopathies and the development and testing of new therapies has long bee... more The study of human cardiomyopathies and the development and testing of new therapies has long been limited by the availability of appropriate in vitro model systems. Cardiomyocytes are highly specialized cells whose internal structure and contractile function are sensitive to the local microenvironment and the combination of mechanical and biochemical cues they receive. The complementary technologies of human induced pluripotent stem cell (hiPSC) derived cardiomyocytes (CMs) and microphysiological systems (MPS) allow for precise control of the genetics and microenvironment of human cells in in vitro contexts. These combined systems also enable quantitative measurement of mechanical function and intracellular organization. This review describes relevant factors in the myocardium microenvironment that affect CM structure and mechanical function and demonstrates the application of several engineered microphysiological systems for studying development, disease, and drug discovery.

A benchmarking model for validation and standardization of traction force microscopy analysis tools

bioRxiv (Cold Spring Harbor Laboratory), Aug 14, 2020

Traction Force Microscopy (TFM) has become a well-established technique to assay the biophysical ... more Traction Force Microscopy (TFM) has become a well-established technique to assay the biophysical force produced by cells cultured on soft substrates of controlled stiffness. However, experimental conditions as well as computational implementations can have a large impact on the analysis results accuracy and reproducibility. While this can be alleviated using appropriate controls and a rigorous analytical approach, the comparison of results across studies remains difficult and there is a need for validation and benchmarking tools. To validate the accuracy of and compare various computational TFM analysis algorithms, we developed a virtual in silico

Simultaneous Replication of Hydrophilic and Superhydrophobic Micropatterns through Area-Selective Monomers Self-Assembly

Advanced Materials Interfaces, Aug 22, 2016

Simultaneous replication of hydrophilic and superhydrophobic micropatterns through areaselective ... more

A predictive model for electrostatically gated nanofluidic channels

Fabrication of nanochannels by replica molding using off-stoichiometry thiol-ene (OSTE) polymer

Fabrication of nanochannels by replica molding using off-stoichiometry thiol-ene (OSTE) polymer

From Macro to Nano : Electrokinetic Transport and Surface Control

Today, the growing and aging population, and the rise of new global threats on human health puts ... more Today, the growing and aging population, and the rise of new global threats on human health puts an increasing demand on the healthcare system and calls for preventive actions. To make existing medical treatments more efficient and widely accessible and to prevent the emergence of new threats such as drug-resistant bacteria, improved diagnostic technologies are needed. Potential solutions to address these medical challenges could come from the development of novel lab-on-chip (LoC) for point-of-care (PoC) diagnostics. At the same time, the increasing demand for sustainable energy calls for the development of novel approaches for energy conversion and storage systems (ECS), to which micro-and nanotechnologies could also contribute. This thesis has for objective to contribute to these developments and presents the results of interdisciplinary research at the crossing of three disciplines of physics and engineering: electrokinetic transport in fluids, manufacturing of micro-and nanofluidic systems, and surface control and modification. By combining knowledge from each of these disciplines, novel solutions and functionalities were developed at the macro-, micro-and nanoscale, towards applications in PoC diagnostics and ECS systems.

Le Secteur Pavillon et Transports à l’Exposition nationale suisse, Lausanne 1964

Keywords: Esthetique ; Histoire et esthetique de l'image ; Section MT Reference SHS-STUDENT-2... more