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22 Ergebnisse
Bereich: Suchergebnisse
Publikation Hematocrit measurement - a high precision on-line measurement system based on impedance spectroscopy for use in hemodialysis machines(2009) Trebbels, Dennis; Zengerle, Roland; Hradetzky, DavidThis paper presents a unique technical approach to measure the proportion of blood volume occupied by red blood cells, the hematocrit value (HCT) on-line and in-line. A practical method has been developed to measure without the need for extracting blood samples out of an existing extracorporeal blood circulation system. The new sensor is based on Impedance Spectroscopy and measures electrical properties of the blood at various frequencies. In order to achieve the required precision resolution the sensor geometry has been optimized by Finite Element Analysis. For sensor readout a digital measurement circuitry based on cheap standard components is developed and allows practical implementation of HCT-sensor devices for the first time. Special care has been taken in order to compensate for the temperature effects.04B - Beitrag KonferenzschriftPublikation Interferometric label-free biomolecular detection system(IOP Publishing Ltd, 2006) Hradetzky, David; Mueller, Claas; Reinecke, HolgerThis work presents a simple evanescent wave sensing system based on an interferometric approach, suitable to meet the requirements of label-free sensor systems for detecting biomolecular interactions. It represents a basic concept towards label-free detection systems in various applications. The basic objectives of transducers for evanescent wave sensing are discussed. An optical detection system based on a interferometric approach using Young's double slit configuration is discussed, set-up and characterized. With refractometric measurements of various sucrose dilutions, the performance of the pure optical set-up is evaluated.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Electrospray application for enchanced delivery of anticancer drugs into cells(Vytautas Magnus university, 2018) Ruzgys, Paulius; Boehringer, Stephan; Tamò, Luca; Šatkauskas, Saulius; Geiser, Thomas; Gazdhar, Amiq; Hradetzky, DavidElectrospray is a process based on applied high electric voltage on liquid, leading to the creation and acceleration of small sized droplets. Electrosprayed suspension with exogenous molecules on cells can trigger intracellular delivery. Here, the application study of anticancer drug delivery via electrospray as an antitumor treatment is presented in vitro and in vivo. In vitro experiments were performed on alveolar epithelial cells (A549). Cell viability was performed with flow cytometry assay. Apoptosis/ necrosis was measured using annexin V/PI kit. In vivo experiments were done with C57BL/6J mice. Lewis lung carcinoma (LLC) cell lines were injected intradermally to induce tumor. Electrospray was performed on tumor by cutting the skin. Tumor size was measured with caliper. Results show triggered PI transfer to cells after electrospray process. Moreover, obtained results in vitro showed successful cisplatin and methotrexate intracellular delivery, resulting in around 90 % of cell viability loss with methotrexate and 70 % of cell viability loss with cisplatin. In vivo experiments reveled a tumor decrease by around 2.5 times in 7 days after electrospray treatment at first and third day with both anticancer drugs. Here we show that electrospray method can be applied to local anticancer drug delivery to cells and tissues. Therefore, such method might be adapted as a clinical anticancer therapy in the future.04B - Beitrag KonferenzschriftPublikation Design of miniaturized electro spray instrument for gene and drug therapeutic treatment of IPF(De Gruyter, 2013) Fiave, Prosper Agbesi; Boehringer, Stephan; Gazdhar, Amiq; Geiser, Thomas; Hradetzky, DavidElectric field accelerated plasmid droplets to permeate tissues has been demonstrated on cell culture and ex-vivo lung tissue of rats using enhanced green fluorescence protein reporter gene for transfection. This opens a window of opportunity to design an electrospray instrument usable within the working channel of bronchoscope to noninvasively treat idiopathic pulmonary fibrosis (IPF). We elaborate a concept and realized a device usable in the working channel of a flexible bronchoscope taking into account restrictions within typical bronchoscopy procedure.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Interferometric sensor platform for biomolecular interaction analysis(VDE, 2005) Hradetzky, David; Müller, Claas; Reinecke, Holger04B - Beitrag KonferenzschriftPublikation An approach towards bronchoscopic-based gene therapy using electrical field accelerated plasmid droplets(IEEE, 2012) Hradetzky, David; Boehringer, Stephan; Geiser, Thomas; Gazdhar, AmiqIdiopathic pulmonary fibrosis (IPF) is a devastating disease affecting the distal lung, due to failure of the alveolar epithelium to heal after micro-injuries, leading to inefficient gas exchange and resulting in death. Therapeutic options are very limited. A new therapeutic approach based on gene therapy restores the self-healing process within the lung in the experimental setup. A basic requirement of this therapy is the successful transduction of genes into the alveolar epithelium in the distal part of the lung, for which a new therapeutic instrument is required. In this paper we present the concept and first experimental results of a device which uses an electrical field to accelerate the charged droplets of plasmid suspension toward the tissue and which overcomes cell membrane with its impact energy. The aim is to develop a therapeutic device capable of being integrated into minimally invasive procedures such as bronchoscopy.04B - Beitrag KonferenzschriftPublikation Interferometrisches Biosensor System(2001) Wikerstål, Andreas; Brandenburg, Albrecht; Hradetzky, David; Krauter, Ralf; Künzel, Christa; Schulte, Heinrich; Stefan, Monika04B - Beitrag KonferenzschriftPublikation Label free detection of biomolecular interactions(IEEE, 2005) Hradetzky, David; Müller, Claas; Reinecke, HolgerThis work presents a simple evanescent wave sensing system based on an interferometric approach suitable to meet the demands on label free sensor systems for the detection of biomolecular interactions especially. It is representing a basic concept towards high throughput application. The system performance and reproducibility was evaluated with refractometric measurements of sucrose dilutions. A mean resolution of the effective refractive index of 3sigma(Deltamacrnmacr eff )=0.9middot10 -6 without averaging and a reproducibility below sigma r =0.1middot10 -6 were achieved. The suitability for the detection of biomolecular interactions was validated with the detection of a DNA hybridization04B - Beitrag KonferenzschriftPublikation Eye-Cam: Sprachgesteuerte Miniaturkamera integriert in einer Brille(2007) Hradetzky, David; Kliche, Kurt; Ehrbrecht, Bernd; Anka, Laszlo; Wölfle, Matthias; Zengerle, Roland04B - Beitrag KonferenzschriftPublikation Miniaturisierte Sensorplattform zur markierungsfreien Detektion biomolekularer Interaktionen(Cuvillier Verlag, 2005) Hradetzky, David02 - Monographie
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