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Articles 1 - 30 of 457

Full-Text Articles in Biomedical Engineering and Bioengineering

Viscoelastic Properties Of Shock Wave Exposed Brain Tissue Subjected To Unconfined Compression Experiments, Annastacia K. Mccarty, Ling Zhang, Sarah Hansen, William J. Jackson, Sarah A. Bentil Dec 2019

Viscoelastic Properties Of Shock Wave Exposed Brain Tissue Subjected To Unconfined Compression Experiments, Annastacia K. Mccarty, Ling Zhang, Sarah Hansen, William J. Jackson, Sarah A. Bentil

Mechanical Engineering Publications

Traumatic brain injuries (TBI) affect millions of people each year. While research has been dedicated to determining the mechanical properties of the uninjured brain, there has been a lack of investigation on the mechanical properties of the brain after experiencing a primary blast-induced TBI. In this paper, whole porcine brains were exposed to a shock wave to simulate blast-induced TBI. First, ten (10) brains were subjected to unconfined compression experiments immediately following shock wave exposure. In addition, 22 brains exposed to a shock wave were placed in saline solution and refrigerated between 30 minutes and 6.0 hours before undergoing ...


Sheet‐Extruded Films From Blends Of Hydroxypropylated And Native Corn Starches, And Their Characterization, Hee-Young Kim, Buddhi P. Lamsal, Jay-Lin Jane, David A. Grewell Aug 2019

Sheet‐Extruded Films From Blends Of Hydroxypropylated And Native Corn Starches, And Their Characterization, Hee-Young Kim, Buddhi P. Lamsal, Jay-Lin Jane, David A. Grewell

Food Science and Human Nutrition Publications

Sheet‐extruded films from the blends of hydroxypropylated normal corn starch (HP) and native normal corn starch (NS) at weight ratios of 100:0, 90:10, 70:30, 50:50, 30:70, and 0:100 were prepared and characterized. Glycerol and water were added as plasticizers at 11 and 27% starch weight, respectively. The highest tensile strength (TS) and longest elongation to break (EB) for dry films were observed at 70:30 HP: NS ratio, which was 25.76 MPa, and 3.97%, respectively. However, TS and EB of this 70:30 blend extruded starch film exhibited low resistance upon ...


Defining Cell Cluster Size By Dielectrophoretic Capture At An Array Of Wireless Electrodes Of Several Distinct Lengths, Joseph T. Banovetz, Min Li, Darshna Pagariya, Sungu Kim, Baskar Ganapathysubramanian, Robbyn Anand Apr 2019

Defining Cell Cluster Size By Dielectrophoretic Capture At An Array Of Wireless Electrodes Of Several Distinct Lengths, Joseph T. Banovetz, Min Li, Darshna Pagariya, Sungu Kim, Baskar Ganapathysubramanian, Robbyn Anand

Chemistry Publications

Clusters of biological cells play an important role in normal and disease states, such as in the release of insulin from pancreatic islets and in the enhanced spread of cancer by clusters of circulating tumor cells. We report a method to pattern cells into clusters having sizes correlated to the dimensions of each electrode in an array of wireless bipolar electrodes (BPEs). The cells are captured by dielectrophoresis (DEP), which confers selectivity, and patterns cells without the need for physical barriers or adhesive interactions that can alter cell function. Our findings demonstrate that this approach readily achieves fine control of ...


Placenta‐On‐A‐Chip: In Vitro Study Of Caffeine Transport Across Placental Barrier Using Liquid Chromatography Mass Spectrometry, Rajeendra L. Pemathilaka, Jeremy D. Caplin, Saurabh S. Aykar, Reza Montazami, Nicole N. Hashemi Mar 2019

Placenta‐On‐A‐Chip: In Vitro Study Of Caffeine Transport Across Placental Barrier Using Liquid Chromatography Mass Spectrometry, Rajeendra L. Pemathilaka, Jeremy D. Caplin, Saurabh S. Aykar, Reza Montazami, Nicole N. Hashemi

Mechanical Engineering Publications

Due to the particular structure and functionality of the placenta, most current human placenta drug testing methods are limited to animal models, conventional cell testing, and cohort/controlled testing. Previous studies have produced inconsistent results due to physiological differences between humans and animals and limited availability of human and/or animal models for controlled testing. To overcome these challenges, a placenta‐on‐a‐chip system is developed for studying the exchange of substances to and from the placenta. Caffeine transport across the placental barrier is studied because caffeine is a xenobiotic widely consumed on a daily basis. Since a fetus ...


Direct Observation Of Early Stages Of Growth Of Multilayered Dna-Templated Au-Pd-Au Core-Shell Nanoparticles In Liquid Phase, Nabraj Bhattarai, Tanya Prozorov Feb 2019

Direct Observation Of Early Stages Of Growth Of Multilayered Dna-Templated Au-Pd-Au Core-Shell Nanoparticles In Liquid Phase, Nabraj Bhattarai, Tanya Prozorov

Ames Laboratory Accepted Manuscripts

We report here on direct observation of early stages of formation of multilayered bimetallic Au-Pd core-shell nanocubes and Au-Pd-Au core-shell nanostars in liquid phase using low-dose in situ scanning transmission electron microscopy (S/TEM) with the continuous flow fluid cell. The reduction of Pd and formation of Au-Pd core-shell is achieved through the flow of the reducing agent. Initial rapid growth of Pd on Au along <111> direction is followed by a slower rearrangement of Pd shell. We propose the mechanism for the DNA-directed shape transformation of Au-Pd core-shell nanocubes to adopt a nanostar-like morphology in the presence of T30 DNA ...


Analyzing Drug Release Kinetics From Water-Soluble Polymers, Sean M. Kelly, Arun K. Upadhyay, Akash Mitra, Balaji Narasimhan Feb 2019

Analyzing Drug Release Kinetics From Water-Soluble Polymers, Sean M. Kelly, Arun K. Upadhyay, Akash Mitra, Balaji Narasimhan

Chemical and Biological Engineering Publications

The ability to develop predictive mathematical models of therapeutic release from pharmaceutical formulations has enormous potential to enhance our understanding of such systems and improve the controlled release of the payload. The current work describes the development and testing of a one-dimensional model of drug transport from amorphous, swelling/dissolving polymers. Model parameters such as the diffusivities of water and drug, the initial loading of the drug, the polymer dissolution rate, drug-polymer interactions, and the tablet thickness were varied, demonstrating the ability to tune the release to be controlled by either drug diffusion or polymer chain disentanglement. In addition, predictions ...


Pentablock Copolymer Micelle Nanoadjuvants Enhance Cytosolic Delivery Of Antigen And Improve Vaccine Efficacy While Inducing Low Inflammation, Sujata Senapati, Ross J. Darling, Darren Loh, Ian C. Schneider, Michael J. Wannemeuhler, Balaji Narasimhan, Surya K. Mallapragada Feb 2019

Pentablock Copolymer Micelle Nanoadjuvants Enhance Cytosolic Delivery Of Antigen And Improve Vaccine Efficacy While Inducing Low Inflammation, Sujata Senapati, Ross J. Darling, Darren Loh, Ian C. Schneider, Michael J. Wannemeuhler, Balaji Narasimhan, Surya K. Mallapragada

Chemistry Publications

As the focus has shifted from traditional killed or live, attenuated vaccines towards subunit vaccines, improvements in vaccine safety have been confronted with low immunogenicity of protein antigens. This issue has been addressed by synthesizing and designing a wide variety of antigen carriers and adjuvants, such as Toll-like receptor agonists (e.g., MPLA, CpG). Studies have focused on optimizing adjuvants for improved cellular trafficking, cytosolic availability, and improved antigen presentation. In this work, we describe the design of novel amphiphilic pentablock copolymer (PBC) adjuvants that exhibit high biocompatibility and reversible pH- and temperature-sensitive micelle formation. We demonstrate improved humoral immunity ...


Degradation And Remodeling Of Epitaxially Grown Collagen Fibrils, Juan Wang, Anuraag Boddupalli, Joseph Koelbl, Dong Hyun Nam, Xin Ge, Kaitlin M. Bratlie, Ian C. Schneider Feb 2019

Degradation And Remodeling Of Epitaxially Grown Collagen Fibrils, Juan Wang, Anuraag Boddupalli, Joseph Koelbl, Dong Hyun Nam, Xin Ge, Kaitlin M. Bratlie, Ian C. Schneider

Materials Science and Engineering Publications

Introduction: The extracellular matrix (ECM) in the tumor microenvironment contains high densities of collagen that are highly aligned, resulting in directional migration called contact guidance that facilitates efficient migration out of the tumor. Cancer cells can remodel the ECM through traction force controlled by myosin contractility or proteolytic activity controlled by matrix metalloproteinase (MMP) activity, leading to either enhanced or diminished contact guidance.

Methods: Recently, we have leveraged the ability of mica to epitaxially grow aligned collagen fibrils in order to assess contact guidance. In this article, we probe the mechanisms of remodeling of aligned collagen fibrils on mica by ...


Development Of Gelatin And Graphene-Based Nerve Regeneration Conduits Using 3d Printing Strategies For Electrical Transdifferentiation Of Mesenchymal Stem Cells, Metin Uz, Maxsam Donta, Meryem Mededovic, Donald S. Sakaguchi, Surya Mallapragada Feb 2019

Development Of Gelatin And Graphene-Based Nerve Regeneration Conduits Using 3d Printing Strategies For Electrical Transdifferentiation Of Mesenchymal Stem Cells, Metin Uz, Maxsam Donta, Meryem Mededovic, Donald S. Sakaguchi, Surya Mallapragada

Chemical and Biological Engineering Publications

In this study, gelatin and graphene-based nerve regeneration conduits/scaffolds possessing tailored 3D microstructures and mechanical properties were fabricated using 3D printing. The effect of 3D conduit microstructure and mechanical properties along with the applied electrical stimuli on mesenchymal stem cell (MSCs) behavior and transdifferentiation into Schwann cell (SC)-like phenotypes were investigated. The results indicated that the gelatin conduits/scaffolds had favorable 3D microstructural and mechanical properties for MSC attachment and growth. Immunocytochemistry results demonstrated that the application of electrical stimuli through the conductive graphene within the gelatin-based 3D microstructure had a profound effect on the differentiation of MSCs ...


Use Of Flexible Sensor To Characterize Biomechanics Of Canine Skin, Austin R. J. Downey, Jin Yan, Eric M. Zellner, Karl H. Kraus, Iris V. Rivero, Simon Laflamme Jan 2019

Use Of Flexible Sensor To Characterize Biomechanics Of Canine Skin, Austin R. J. Downey, Jin Yan, Eric M. Zellner, Karl H. Kraus, Iris V. Rivero, Simon Laflamme

Civil, Construction and Environmental Engineering Publications

Background: Suture materials and techniques are frequently evaluated in ex vivo studies by comparing tensile strengths. However, the direct measurement techniques to obtain the tensile forces in canine skin are not available, and, therefore, the conditions suture lines undergo is unknown. A soft elastomeric capacitor is used to monitor deformation in the skin over time by sensing strain. This sensor was applied to a sample of canine skin to evaluate its capacity to sense strain in the sample while loaded in a dynamic material testing machine. The measured strain of the sensor was compared with the strain measured by the ...


Investigating The Role Of Coil Designs And Anatomical Variations In Cerebellar Tms, Xiaojing Zhong, Priyam Rastogi, Yifei Wang, Erik G. Lee, David C. Jiles Jan 2019

Investigating The Role Of Coil Designs And Anatomical Variations In Cerebellar Tms, Xiaojing Zhong, Priyam Rastogi, Yifei Wang, Erik G. Lee, David C. Jiles

Electrical and Computer Engineering Publications

Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique that is used for treating various neurological disorders such as major depressive disorder. TMS has been gaining popularity in the field of neurostimulation of the cerebellum, since the cerebellum is a complex structure connected with almost the entire central nervous system and TMS has promise for non-invasively probing cerebellar function. Recent studies have discovered that the cerebellum plays an important role not only in motor planning and behavior but also in the cognitive domain. However, few studies have explored how different coil designs and anatomical variations affect the effectiveness of cerebellar ...


Interleukin-1 Alpha Increases Anti-Tumor Efficacy Of Cetuximab In Head And Neck Squamous Cell Carcinoma, Madelyn Espinosa-Cotton, Samuel N. Rodman Iii, Kathleen A. Ross, Isaac J. Jensen, Kenley Sangodeyi-Miller, Ayana J. Mclaren, Rachel A. Dahl, Katherine N. Gibson-Corley, Adam T. Koch, Yang-Xin Fu, Vladimir P. Badovinac, Douglas Laux, Balaji Narasimhan, Andrean L. Simons Jan 2019

Interleukin-1 Alpha Increases Anti-Tumor Efficacy Of Cetuximab In Head And Neck Squamous Cell Carcinoma, Madelyn Espinosa-Cotton, Samuel N. Rodman Iii, Kathleen A. Ross, Isaac J. Jensen, Kenley Sangodeyi-Miller, Ayana J. Mclaren, Rachel A. Dahl, Katherine N. Gibson-Corley, Adam T. Koch, Yang-Xin Fu, Vladimir P. Badovinac, Douglas Laux, Balaji Narasimhan, Andrean L. Simons

Chemical and Biological Engineering Publications

Background: Despite the high prevalence of epidermal growth factor receptor (EGFR) overexpression in head and neck squamous cell carcinomas (HNSCCs), incorporation of the EGFR inhibitor cetuximab into the clinical management of HNSCC has not led to significant changes in long-term survival outcomes. Therefore, the identification of novel therapeutic approaches to enhance the clinical efficacy of cetuximab could lead to improved long-term survival for HNSCC patients. Our previous work suggests that EGFR inhibition activates the interleukin-1 (IL-1) pathway via tumor release of IL-1 alpha (IL-1α), although the clinical implications of activating this pathway are unclear in the context of cetuximab therapy ...


Overview Of Sepsis And Sepsis Biomarker Detection, Souvik Kundu Jan 2019

Overview Of Sepsis And Sepsis Biomarker Detection, Souvik Kundu

Creative Components

Sepsis being a fatal physiological state due to an imbalance in the immune system caused by infection, and one of the most common cause for millions of deaths in the non-coronary intensive care unit worldwide requires special attention in its diagnostic methods and cure. Therefore an understanding of literature related to sepsis is of utmost importance. With the advent of inter-disciplinary research, the study and diagnosis of sepsis problem are not limited to the medical field, rather it requires interventions and active participation of other fields of science and technology. However, often subject matter from interdisciplinary research is expounded in ...


Design And Synthesis Of Multivalent Α-1,2-Trimannose-Linked Bioerodible Microparticles For Applications In Immune Response Studies Of Leishmania Major Infection, Chelsea L. Rintelmann, Tara Grinnage-Pulley, Kathleen Ross, Daniel E. K. Kabotso, Angela Toepp, Anne Cowell, Christine Petersen, Balaji Narasimhan, Nicola Pohl Jan 2019

Design And Synthesis Of Multivalent Α-1,2-Trimannose-Linked Bioerodible Microparticles For Applications In Immune Response Studies Of Leishmania Major Infection, Chelsea L. Rintelmann, Tara Grinnage-Pulley, Kathleen Ross, Daniel E. K. Kabotso, Angela Toepp, Anne Cowell, Christine Petersen, Balaji Narasimhan, Nicola Pohl

Chemical and Biological Engineering Publications

Leishmaniasis, a neglected tropical disease, currently infects approximately 12 million people worldwide with 1 to 2 million new cases each year in predominantly underdeveloped countries. The treatment of the disease is severely underdeveloped due to the ability of the Leishmania pathogen to evade and abate immune responses. In an effort to develop anti-leishmaniasis vaccines and adjuvants, novel carbohydrate-based probes were made to study the mechanisms of immune modulation. In this study, a new bioerodible polyanhydride microparticle was designed and conjugated with a glycodendrimer molecular probe. This molecular probe incorporates a pathogen-like multivalent display of α-1,2-trimannose, for which a more ...


How Crosslinking Mechanisms Of Methacrylated Gellan Gum Hydrogels Alter Macrophage Phenotype, Zhuqing Li, Kaitlin M. Bratlie Dec 2018

How Crosslinking Mechanisms Of Methacrylated Gellan Gum Hydrogels Alter Macrophage Phenotype, Zhuqing Li, Kaitlin M. Bratlie

Materials Science and Engineering Publications

In tissue engineering scaffolds, macrophages play a critical role in determining the host response to implanted biomaterials. Macrophage phenotype is dynamic throughout the host response, and a balance of phenotypes is essential for timely progression from injury to proper wound healing. Therefore, it is important to predict how materials will modulate the response of macrophages. In this study, we investigated the effect of methacrylated gellan gum hydrogels on macrophage phenotype and proliferation with the ultimate goal of improving rational design of biomedical implants. Naïve, along with classically and alternatively activated RAW 264.7 macrophages were seeded on methacrylated gellan gum ...


Microtissue Size And Cell-Cell Communication Modulate Cell Migration In Arrayed 3d Collagen Gels, Jacob A. M. Nuhn, Shenmin Gong, Xiangchen Che, Long Que, Ian C. Schneider Sep 2018

Microtissue Size And Cell-Cell Communication Modulate Cell Migration In Arrayed 3d Collagen Gels, Jacob A. M. Nuhn, Shenmin Gong, Xiangchen Che, Long Que, Ian C. Schneider

Chemical and Biological Engineering Publications

Cells communicate through the extracellular matrix (ECM) in many physiological and pathological processes. This is particularly important during cell migration, where cell communication can alter both the speed and the direction of migration. However, most cell culture systems operate with large volumes relative to cell numbers, creating low cell densities and diluting factors that mediate cell communication. Furthermore, they lack the ability to isolate single cells or small groups of cells. Droplet forming devices allow for an ability to embed single or small groups of cells into small volume segregated 3D environments, increasing the cell density to physiological levels. In ...


Primer Set 2.0 For Highly Parallel Qpcr Array Targeting Antibiotic Resistance Genes And Mobile Genetic Elements, Robert D. Stedtfeld, Xueping Guo, Tiffany M. Stedtfeld, Hongjie Sheng, Maggie R. Williams, Kristin Hauschild, Santosh Gunturu, Leo Tift, Fang Wang, Adina Howe, Benli Chai, James R. Cole, James M. Tiedje, Syed A. Hashsham Sep 2018

Primer Set 2.0 For Highly Parallel Qpcr Array Targeting Antibiotic Resistance Genes And Mobile Genetic Elements, Robert D. Stedtfeld, Xueping Guo, Tiffany M. Stedtfeld, Hongjie Sheng, Maggie R. Williams, Kristin Hauschild, Santosh Gunturu, Leo Tift, Fang Wang, Adina Howe, Benli Chai, James R. Cole, James M. Tiedje, Syed A. Hashsham

Agricultural and Biosystems Engineering Publications

The high-throughput antibiotic resistance gene (ARG) qPCR array, initially published in 2012, is increasingly used to quantify resistance and mobile determinants in environmental matrices. Continued utility of the array; however, necessitates improvements such as removing or redesigning questionable primer sets, updating targeted genes and coverage of available sequences. Towards this goal, a new primer design tool (EcoFunPrimer) was used to aid in identification of conserved regions of diverse genes. The total number of assays used for diverse genes was reduced from 91 old primer sets to 52 new primer sets, with only a 10% loss in sequence coverage. While the ...


Treatment Of Neurodegenerative Disorders Through The Blood-Brain Barrier Using Nanocarriers, Nitya Poovaiah, Zahra Davoudi, Haisheng Peng, Benjamin Schlichtmann, Surya K. Mallapragada, Balaji Narasimhan, Qun Wang Aug 2018

Treatment Of Neurodegenerative Disorders Through The Blood-Brain Barrier Using Nanocarriers, Nitya Poovaiah, Zahra Davoudi, Haisheng Peng, Benjamin Schlichtmann, Surya K. Mallapragada, Balaji Narasimhan, Qun Wang

Chemical and Biological Engineering Publications

Neurodegenerative diseases refer to disorders of the central nervous system (CNS) that are caused by neuronal degradations, dysfunctions, or death. Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease (APHD) are regarded as the three major neurodegenerative diseases. There is a vast body of literature on the causes and treatments of these neurodegenerative diseases. However, the main obstacle in developing an effective treatment strategy is the permeability of the treatment components to the blood-brain barrier (BBB). Several strategies have been developed to improve this obstruction. For example, nanomaterials facilitate drug delivery to the BBB due to their size. They ...


Fabrication And Evaluation Of Poly(Lactic Acid), Chitosan, And Tricalcium Phosphate Biocomposites For Guided Bone Regeneration, Srikanthan Ramesh, Lisa Lungaro, Dimitrios Tsikritsis, Eric Weflen, Iris V. Rivero Aug 2018

Fabrication And Evaluation Of Poly(Lactic Acid), Chitosan, And Tricalcium Phosphate Biocomposites For Guided Bone Regeneration, Srikanthan Ramesh, Lisa Lungaro, Dimitrios Tsikritsis, Eric Weflen, Iris V. Rivero

Industrial and Manufacturing Systems Engineering Publications

This study presents and evaluates an approach for fabricating poly(lactic acid) (PLA)/chitosan (CS)/tricalcium phosphate (TCP) electrospun scaffolds for guided bone regeneration, a dental procedure that uses membranes to direct and delineate regions of osteogenesis. Biomaterials were pre‐processed using cryomilling, a solid‐state grinding technique that facilitates the generation of powdered biocomposites conducive to electrospinning. X‐ray diffraction (XRD) confirmed the generation of cryomilled blends consisting of PLA, CS, and TCP. Results from the differential scanning calorimetry showed an upward shift in glass transition temperature and an increase in crystallinity with the inclusion of TCP reinforcing the ...


Shaped 3d Microcarriers For Adherent Cell Culture And Analysis, Chueh-Yu Wu, Daniel Stoecklein, Aditya Kommajosula, Jonathan Lin, Keegan Owsley, Baskar Ganapathysubramanian, Dino Di Carlo Aug 2018

Shaped 3d Microcarriers For Adherent Cell Culture And Analysis, Chueh-Yu Wu, Daniel Stoecklein, Aditya Kommajosula, Jonathan Lin, Keegan Owsley, Baskar Ganapathysubramanian, Dino Di Carlo

Mechanical Engineering Publications

Standard tissue culture of adherent cells is known to poorly replicate physiology and often entails suspending cells in solution for analysis and sorting, which modulates protein expression and eliminates intercellular connections. To allow adherent culture and processing in flow, we present 3D-shaped hydrogel cell microcarriers, which are designed with a recessed nook in a first dimension to provide a tunable shear-stress shelter for cell growth, and a dumbbell shape in an orthogonal direction to allow for self-alignment in a confined flow, important for processing in flow and imaging flow cytometry. We designed a method to rapidly design, using the genetic ...


Fluorescent Nanodiamonds: Past, Present, And Future, Masfer H. Alkahtani, Fahad Alghannam, Linkun Jiang, Abdulrahman Almethen, Arfaan A. Rampersaud, Robert Brick, Carmen L. Gomes, Marlan O. Scully, Philip R. Hemmer Jul 2018

Fluorescent Nanodiamonds: Past, Present, And Future, Masfer H. Alkahtani, Fahad Alghannam, Linkun Jiang, Abdulrahman Almethen, Arfaan A. Rampersaud, Robert Brick, Carmen L. Gomes, Marlan O. Scully, Philip R. Hemmer

Mechanical Engineering Publications

Multi-color fluorescent nanodiamonds (FNDs) containing a variety of color centers are promising fluorescent markers for biomedical applications. Compared to colloidal quantum dots and organic dyes, FNDs have the advantage of lower toxicity, exceptional chemical stability, and better photostability. They can be surface functionalized by techniques similar to those used for other nanoparticles. They exhibit a variety of emission wavelengths from visible to near infrared, with narrow or broad bandwidths depending on their color centers. In addition, some color centers can detect changes in magnetic fields, electric fields, and temperature. In this article review, we will discuss the current trends in ...


A Photoactivatable Bodipy Probe For Localization‐Based Super‐Resolution Cellular Imaging, Chamari S. Wijesooriya, Julie A. Peterson, Pradeep Shrestha, Elizabeth J. Gehrmann, Arthur H. Winter, Emily Smith Jul 2018

A Photoactivatable Bodipy Probe For Localization‐Based Super‐Resolution Cellular Imaging, Chamari S. Wijesooriya, Julie A. Peterson, Pradeep Shrestha, Elizabeth J. Gehrmann, Arthur H. Winter, Emily Smith

Ames Laboratory Accepted Manuscripts

The synthesis and application of a photoactivatable boron‐alkylated BODIPY probe for localization‐based super‐resolution microscopy is reported. Photoactivation and excitation of the probe is achieved by a previously‐unknown boron‐photodealkylation reaction with a single low‐power visible laser and without requiring the addition of reducing agents or oxygen scavengers in the imaging buffer. These features lead to a versatile probe for localization‐based microscopy of biological systems. The probe can be easily linked to nucleophile‐containing molecules to target specific cellular organelles. By attaching paclitaxel to the photoactivatable BODIPY, in vitro and in vivo super‐resolution imaging ...


Chemically Modified Gellan Gum Hydrogels With Tunable Properties For Use As Tissue Engineering Scaffolds, Zihao Xu, Zhuqing Li, Shan Jiang, Kaitlin M. Bratlie Jun 2018

Chemically Modified Gellan Gum Hydrogels With Tunable Properties For Use As Tissue Engineering Scaffolds, Zihao Xu, Zhuqing Li, Shan Jiang, Kaitlin M. Bratlie

Chemical and Biological Engineering Publications

Gellan gum is a naturally occurring polymer that can cross-link in the presence of divalent cations to form biocompatible hydrogels. However, physically cross-linked gellan gum hydrogels lose their stability under physiological conditions, thus restricting the applications of these hydrogels in vivo. To improve the mechanical strength of the gels, we incorporated methacrylate into the gellan gum and chemically cross-linked the hydrogel through three polymerization methods: step growth through thiol–ene photoclick chemistry, chain-growth via photopolymerization, and mixed model in which both mechanisms were employed. Methacrylation was confirmed and quantified by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared ...


An Anisotropic Constitutive Model For Immersogeometric Fluid–Structure Interaction Analysis Of Bioprosthetic Heart Valves, Michael C.H. Wu, Rana Zakerzadeh, David Kamensky, Josef Kiendl, Michael S. Sacks, Ming-Chen Hsu Jun 2018

An Anisotropic Constitutive Model For Immersogeometric Fluid–Structure Interaction Analysis Of Bioprosthetic Heart Valves, Michael C.H. Wu, Rana Zakerzadeh, David Kamensky, Josef Kiendl, Michael S. Sacks, Ming-Chen Hsu

Mechanical Engineering Publications

This paper considers an anisotropic hyperelastic soft tissue model, originally proposed for native valve tissue and referred to herein as the Lee–Sacks model, in an isogeometric thin shell analysis framework that can be readily combined with immersogeometric fluid–structure interaction (FSI) analysis for high-fidelity simulations of bioprosthetic heart valves (BHVs) interacting with blood flow. We find that the Lee–Sacks model is well-suited to reproduce the anisotropic stress–strain behavior of the cross-linked bovine pericardial tissues that are commonly used in BHVs. An automated procedure for parameter selection leads to an instance of the Lee–Sacks model that matches ...


Impact Of Non-Brain Anatomy And Coil Orientation On Inter- And Intra-Subject Variability In Tms At Midline, Erik G. Lee, Priyam Rastogi, Ravi L. Hadimani, David C. Jiles, Joan A. Camprodon May 2018

Impact Of Non-Brain Anatomy And Coil Orientation On Inter- And Intra-Subject Variability In Tms At Midline, Erik G. Lee, Priyam Rastogi, Ravi L. Hadimani, David C. Jiles, Joan A. Camprodon

Electrical and Computer Engineering Publications

Objective: To investigate inter-subject variability with respect to cerebrospinal fluid thickness and brain-scalp distance, and to investigate intra-subject variability with different coil orientations.

Methods: Simulations of the induced electric field (E-Field) using a figure-8 coil over the vertex were conducted on 50 unique head models, and varying orientations on 25 models. Metrics exploring stimulation intensity, spread, and localization were used to describe inter-subject variability and effects of non-brain anatomy.

Results: Both brain-scalp distance and CSF thickness were correlated with weaker stimulation intensity, and greater spread. Coil rotations show that for the dorsal portion of the stimulated brain, E-Field intensities are ...


Tip-Enhanced Raman Scattering Of Dna Aptamers For Listeria Monocytogenes, Siyu He, Hongyuan Li, Carmen L. Gomes, Dmitri V. Voronine May 2018

Tip-Enhanced Raman Scattering Of Dna Aptamers For Listeria Monocytogenes, Siyu He, Hongyuan Li, Carmen L. Gomes, Dmitri V. Voronine

Mechanical Engineering Publications

Optical detection and conformational mapping of aptamers are important for improving medical and biosensing technologies and for better understanding of biological processes at the molecular level. The authors investigate the vibrational signals of deoxyribonucleic acid aptamers specific to Listeria monocytogenes immobilized on gold substrates using tip-enhanced Raman scattering (TERS) spectroscopy and nanoscale imaging. The authors compare topographic and nano-optical signals and investigate the fluctuations of the position-dependent TERS spectra. They perform spatial TERS mapping with 3 nm step size and discuss the limitation of the resulting spatial resolution under the ambient conditions. TERS mapping provides information about the chemical composition ...


Kinetic Modeling Of Corn Fermentation With S. Cerevisiae Using A Variable Temperature Strategy, Augusto C. M. Souza, Mohammad Mousaviraad, Kenneth O. M. Mapoka, Kurt A. Rosentrater Apr 2018

Kinetic Modeling Of Corn Fermentation With S. Cerevisiae Using A Variable Temperature Strategy, Augusto C. M. Souza, Mohammad Mousaviraad, Kenneth O. M. Mapoka, Kurt A. Rosentrater

Agricultural and Biosystems Engineering Publications

While fermentation is usually done at a fixed temperature, in this study, the effect of having a controlled variable temperature was analyzed. A nonlinear system was used to model batch ethanol fermentation, using corn as substrate and the yeast Saccharomyces cerevisiae, at five different fixed and controlled variable temperatures. The lower temperatures presented higher ethanol yields but took a longer time to reach equilibrium. Higher temperatures had higher initial growth rates, but the decay of yeast cells was faster compared to the lower temperatures. However, in a controlled variable temperature model, the temperature decreased with time with the initial value ...


Simulations Of Hydrogel-Coated Neural Microelectrodes To Assess Biocompatibility Improvement Using Strain As A Metric For Micromotion, Sarah A. Bentil, Rebecca B. Dupaix Apr 2018

Simulations Of Hydrogel-Coated Neural Microelectrodes To Assess Biocompatibility Improvement Using Strain As A Metric For Micromotion, Sarah A. Bentil, Rebecca B. Dupaix

Mechanical Engineering Publications

This study investigates the benefit of coating silicon-substrate microelectrode arrays with hydrogel material for improved biocompatibility. Varying coating thicknesses and hydrogel material descriptions were considered to determine the impact on reducing strain in the surrounding brain tissue caused by relative micromotion of the electrode. Finite element simulations were used to explore biocompatibility by focusing on the longitudinal micromotion of an implanted single electrode shank. The finite element model for the brain and electrode, both with and without the hydrogel coating, remained constant. Three constitutive models were considered to describe the brain and/or hydrogel material: linear elastic, hyperviscoelastic, and fractional ...


A Framework For Designing Patient‐Specific Bioprosthetic Heart Valves Using Immersogeometric Fluid–Structure Interaction Analysis, Fei Xue, Simone Morganti, Rana Zakerzadeh, David Kamensky, Ferdinando Auricchio, Alessandro Reali, Thomas J.R. Hughes, Michael S. Sacks, Ming-Chen Hsu Apr 2018

A Framework For Designing Patient‐Specific Bioprosthetic Heart Valves Using Immersogeometric Fluid–Structure Interaction Analysis, Fei Xue, Simone Morganti, Rana Zakerzadeh, David Kamensky, Ferdinando Auricchio, Alessandro Reali, Thomas J.R. Hughes, Michael S. Sacks, Ming-Chen Hsu

Mechanical Engineering Publications

Numerous studies have suggested that medical image derived computational mechanics models could be developed to reduce mortality and morbidity due to cardiovascular diseases by allowing for patient‐specific surgical planning and customized medical device design. In this work, we present a novel framework for designing prosthetic heart valves using a parametric design platform and immersogeometric fluid–structure interaction (FSI) analysis. We parameterize the leaflet geometry using several key design parameters. This allows for generating various perturbations of the leaflet design for the patient‐specific aortic root reconstructed from the medical image data. Each design is analyzed using our hybrid arbitrary ...


A Contact Formulation Based On A Volumetric Potential: Application To Isogeometric Simulations Of Atrioventricular Valves, David Kamensky, Fei Xue, Chung-Hao Lee, Jinhui Yan, Yuri Bazilevs, Ming-Chen Hsu Mar 2018

A Contact Formulation Based On A Volumetric Potential: Application To Isogeometric Simulations Of Atrioventricular Valves, David Kamensky, Fei Xue, Chung-Hao Lee, Jinhui Yan, Yuri Bazilevs, Ming-Chen Hsu

Mechanical Engineering Publications

This work formulates frictionless contact between solid bodies in terms of a repulsive potential energy term and illustrates how numerical integration of the resulting forces is computationally similar to the “pinball algorithm” proposed and studied by Belytschko and collaborators in the 1990s. We thereby arrive at a numerical approach that has both the theoretical advantages of a potential-based formulation and the algorithmic simplicity, computational efficiency, and geometrical versatility of pinball contact. The singular nature of the contact potential requires a specialized nonlinear solver and an adaptive time stepping scheme to ensure reliable convergence of implicit dynamic calculations. We illustrate the ...