Electrically stimulated gene expression under exogenously applied electric fields

Introduction: Electrical stimulation, the application of an electric field to cells and tissues grown in culture to accelerate growth and tight junction formation among endothelial cells, could be impactful in cardiovascular tissue engineering, allotransplantation, and wound healing.Methods: Using Electrical Cell Stimulation And Recording Apparatus (ECSARA), the exploration of the stimulatory influences of electric fields of different magnitude and frequencies on growth and proliferation, trans endothelial electrical resistance (TEER) and gene expression of human endothelia cells (HUVECs) were explored.Results: Within the range of endogenous electrical pulses studied, frequency was found to be more significant (p = 0.05) than voltage in influencing HUVEC gene expression. Localization of Yes Associated Protein (YAP) and expression of CD-144 are shown to be consistent with temporal manifestations of TEER.Discussion: This work introduces the field of electromics, the study of cellular gene expression profiles and their implications under the influence of exogenously applied electric fields. Homology of electrobiology and mechanobiology suggests use of such exogenous cues in tissue and regenerative engineering

Supramolecular glucose oxidase-SWNT conjugates formed by ultrasonication: effect of tube length, functionalization and processing time

BACKGROUND: Generation-3 (Gen-3) biosensors and advanced enzyme biofuel cells will benefit from direct electron transfer to oxidoreductases facilitated by single-walled carbon nanotubes (SWNTs). METHODS: Supramolecular conjugates of SWNT-glucose oxidase (GOx-SWNT) were produced via ultrasonic processing. Using a Plackett-Burman experimental design to investigate the process of tip ultrasonication (23 kHz), conjugate formation was investigated as a function of ultrasonication times (0, 5, 60 min) and functionalized SWNTs of various tube lengths (SWNT-X-L), (X = −OH or -COOH and L = 3.0 μm, 7.5 μm). RESULTS: Enzyme activity (K(M), k(cat), k(cat)/K(M), v(max) and n (the Hill parameter)) of pGOx (pristine), sGOx (sonicated) and GOx-SWNT-X-L revealed that sonication of any duration increased both K(M) and k(cat) of GOx but did not change k(cat)/K(M). Functionalized tubes had the most dramatic effect, reducing both K(M) and k(cat) and reducing k(cat)/K(M). UV–vis spectra over the range of 300 to 550 nm of native enzyme-bound FAD (λ(max) at 381 and 452 nm) or the blue-shifted solvated FAD of the denatured enzyme (λ(max) at 377 and 448 nm) revealed that ultrasonication up to 60 minutes had no influence on spectral characteristics of FAD but that the longer SWNTs caused some partial denaturation leading to egress of FAD. Circular dichroism spectral analysis of the 2° structure showed that sonication of any duration caused enrichment in the α-helical content at the sacrifice of the unordered sequences in GOx while the presence of SWNTs, regardless of length and/or functionality, reduced the β-sheet content of pristine GOx. Surface profiling by white light interferometry revealed that ultrasonication produced some aggregation of GOx and that GOx effectively debundled the SWNT. CONCLUSIONS: Supramolecular conjugates formed from shorter, -OH functionalized SWNTs using longer sonication times (60 min) gave the most favored combination for forming bioactive conjugates

Biofabrication and Evaluation, in vitro and in vivo, of a Dual Responsive Glucose and Lactate Implantable Biosensor in a Piglet Trauma Model

With the current state of progress in trauma management by first responders, there is a need for development of an electrochemical biotransducer that can be used with a wireless implantable biosensor system for continual measurement of interstitial glucose and lactate; beginning from the site of the accident and en-route to a trauma center. Fabrication of oxidoreductase enzyme-rich biorecognition membranes deposited via pyrrole electropolymerization at microfabricated electrodes has been achieved. This construct was then electrochemically overoxidzed to create a non-conductive enzyme-hosting polymer film and finally the entire biotransducer was coated with a phosphorylcholine-containing biomimetic hydrogel to mitigate biofouling and reduce the foreign body response. A catalytic layer of Ni-hexacyanoferrate placed at the electrode-enzyme interface for enhanced peroxide response produced a 20-fold increase (14.19 nA vs. 0.7 nA) in buffered H2O2 measured at 650 mV vs. Ag/AgCl. In vitro characterization showed a sensitivity of 0.68 mA/cm2/mM and 0.36 mA/cm2/mM and a limit of detection of 0.05 mM and 7.9 mM for glucose and lactate respectively

Fully Integrated Biochip Platforms for Advanced Healthcare

Recent advances in microelectronics and biosensors are enabling developments of innovative biochips for advanced healthcare by providing fully integrated platforms for continuous monitoring of a large set of human disease biomarkers. Continuous monitoring of several human metabolites can be addressed by using fully integrated and minimally invasive devices located in the sub-cutis, typically in the peritoneal region. This extends the techniques of continuous monitoring of glucose currently being pursued with diabetic patients. However, several issues have to be considered in order to succeed in developing fully integrated and minimally invasive implantable devices. These innovative devices require a high-degree of integration, minimal invasive surgery, long-term biocompatibility, security and privacy in data transmission, high reliability, high reproducibility, high specificity, low detection limit and high sensitivity. Recent advances in the field have already proposed possible solutions for several of these issues. The aim of the present paper is to present a broad spectrum of recent results and to propose future directions of development in order to obtain fully implantable systems for the continuous monitoring of the human metabolism in advanced healthcare applications

Application of a correlation correction factor in a microarray cross-platform reproducibility study

Background Recent research examining cross-platform correlation of gene expression intensities has yielded mixed results. In this study, we demonstrate use of a correction factor for estimating cross-platform correlations. Results In this paper, three technical replicate microarrays were hybridized to each of three platforms. The three platforms were then analyzed to assess both intra- and cross-platform reproducibility. We present various methods for examining intra-platform reproducibility. We also examine cross-platform reproducibility using Pearson\u27s correlation. Additionally, we previously developed a correction factor for Pearson\u27s correlation which is applicable when X and Y are measured with error. Herein we demonstrate that correcting for measurement error by estimating the disattenuated correlation substantially improves cross-platform correlations. Conclusion When estimating cross-platform correlation, it is essential to thoroughly evaluate intra-platform reproducibility as a first step. In addition, since measurement error is present in microarray gene expression data, methods to correct for attenuation are useful in decreasing the bias in cross-platform correlation estimates

Welcome to Bioengineering: A New Open-Access Journal

It is my great pleasure to welcome you to a new open access journal, Bioengineering, which represents a scope that fits squarely with the core expertise and growing ambitions and interests of bioengineers globally. Of particular interest are the transdisciplinary and translational research represented by the activities within centers and institutes where the biological sciences and engineering disciplines cohabit seamlessly for a focus on solutions to global challenges in human, veterinary and ecological health, bioenergy, bioprocess and sustainability. Bioengineering emphasizes the publication of novel and high quality peer reviewed articles via an open access platform. The scope includes: [...

Synthesis and characterization of polyacetylene

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1983.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.Vita.Includes bibliographical references.by Anthony Guiseppe-Elie.Sect.1. Stability of doped polyacetylene--Sect.2. Surface chemistry of polyacetylene.Sc.D

Implantable Wireless Dual-analyte Biosensor for Trauma Patient Monitoring and Management

Amperometric enzyme-based biosensors are being designed as rapidly deployable, minimally invasive diagnostic, microchip technology for the continual measurement of metabolic markers of trauma, such as glucose and lactate. Dual responsive, multi-disc electrode-array working electrodes consisting of 37 platinum microdiscs (d=50 µm, d/r=4) were coated with biosmart hydrogel. Electropolymerization of polypyrrole was used to generate a conducting electroactive polymer (0.1-250 mC/cm2) that formed an interpenetrating network throughout the biosmart hydrogel while simultaneously entrapping enzymes. Biosensors had a response time of 2-8s. Linear ranges for glucose response of the implantable MDEA system were 1-5 mM and 8-33 mM. A sensitivity of 0.42 µA/cm^2/mM, a KMapp of 0.566 mM, and an Imax of 5.40 µA/cm^2 were observed. The detection limit was 0.02 mM. A precise dose response within the physiologically relevant range of glucose was observed. Polypyrrole decreased sensitivity to negatively charged interferrents with a rejection ratio of 12:1. Interferrent response was limited to 3-5% of the total response to glucose at low concentration. The system was stable while stored in PBS and demonstrated increasing sensitivity over 21 days. Dual analyte sensing using a wireless potentiostat was successful with minimal crosstalk between electrochemical cells. Error between cells did not exceed 5%

Polyplex Formation Influences Release Mechanism of Mono- and Di-Valent Ions from Phosphorylcholine Group Bearing Hydrogels

The release of monovalent potassium and divalent calcium ions from zwitterionic phosphorylcholine containing poly(2-hydroxyethyl methacrylate) (pHEMA)-based hydrogels was studied and the effects of polymer swelling, ion valence and temperature were investigated. For comparison, ions were loaded during hydrogel formulation or loaded by partitioning following construct synthesis. Using the Koshmeyer-Peppas release model, the apparent diffusion coefficient, Dapp, and diffusional exponents, n, were Dapp (pre-K+) = 2.03 × 10−5, n = 0.4 and Dapp (post-K+) = 1.86 × 10−5, n = 0.33 respectively, indicative of Fickian transport. The Dapp (pre-Ca2+) = 3.90 × 10−6, n = 0.60 and Dapp (post-Ca2+) = 2.85 × 10−6, n = 0.85, respectively, indicative of case II and anomalous transport. Results indicate that divalent cations form cation-polyelectrolyte anion polymer complexes while monovalent ions do not. Temperature dependence of potassium ion release was shown to follow an Arrhenius-type relation with negative apparent activation energy of −19 ± 15 while calcium ion release was temperature independent over the physiologically relevant range (25–45 °C) studied. The negative apparent activation energy may be due to temperature dependent polymer swelling. No effect of polymer swelling on the diffusional exponent or rate constant was found suggesting polymer relaxation occurs independent of polymer swelling

Improved Performance of Li-ion Polymer Batteries Through Improved Pulse Charging Algorithm

Pulse charging of lithium-ion polymer batteries (LiPo), when properly implemented, offers increased battery charge and energy efficiencies and improved safety for electronic device consumers. Investigations of the combined impact of pulse charge duty cycle and frequency of the pulse charge current on the performance of lithium-ion polymer (LiPo) batteries used the Taguchi orthogonal arrays (OA) to identify optimal and robust pulse charging parameters that maximize battery charge and energy efficiencies while decreasing charge time. These were confirmed by direct comparison with the commonly applied benchmark constant current-constant voltage (CC–CV) charging method. The operation of a pulse charger using identified optimal parameters resulted in charge time reduction by 49% and increased charge and energy efficiencies of 2% and 12% respectively. Furthermore, when pulse charge current factors, such as frequency and duty cycle were considered, it was found that the duty cycle of the pulse charge current had the most impact on the cycle life of the LiPo battery and that the cycle life could be increased by as much as 100 cycles. Finally, the charging temperature was found to have the most statistically significant impact on the temporarily evolving LiPo battery impedance, a measure of its degradation