2022-07, Etter, Philippe, Lucano, Elena, Hradetzky, David

2012, Hradetzky, David, Boehringer, Stephan, Geiser, Thomas, Gazdhar, Amiq

Idiopathic 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.

2006, Hradetzky, David, Mueller, Claas, Reinecke, Holger

This 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.

2001, Wikerstål, Andreas, Brandenburg, Albrecht, Hradetzky, David, Krauter, Ralf, Künzel, Christa, Schulte, Heinrich, Stefan, Monika

2018, Gullo, Maurizio, Köser, Joachim, Ruckli, Oliver, Eigenmann, Andrej, Hradetzky, David

This paper presents a fabrication method for rapid prototyping of 3D biomaterial constructs with vascular structures. The method relies on poloxamer fugitive ink, which is over casted with a custom-made alginate based model extracellular matrix (ECM). The presented method is simple to implement and compatible with standard cell culture workflows used in biomedical research and pharmaceutical development. We present the material preparation, gelation properties and printing methods in detail. First experiments demonstrate the suitability of the ECM constructs for 3D tissue culture.

2009, Trebbels, D., Hradetzky, David, Zengerle, R.

This paper presents a new design for an on-line and in-line hematocrit (HCT) sensor. Special feature of the sensor is the capability to measure the hematocrit of a blood sample inside standard plastic tubing widely used in medical equipment. No blood sample has to be extracted out of existing extracorporeal blood circulation systems such as hemodialysis machines or heart-lung machines. The sensor principle is based on electrical impedance spectroscopy. Dielectric properties of the blood and the plastic tubing are measured at various frequencies. In order to optimize the sensitivity, a unique electrode configuration is developed and optimized by Finite Element Simulation. The new electrode design optimizes the overall sensitivity of the sensor towards a change in dielectric properties of the blood caused by the HCT value and therefore decreases the sensitivity to side effects caused by temperature drift and component tolerances. As a result of the optimized overall sensor performance the complexity of a sensor readout circuitry can be reduced to a minimum which leads to an unmatched price-performance ratio for a complete measurement system.

2005, Hradetzky, David

2013, Fiave, Prosper Agbesi, Boehringer, Stephan, Gazdhar, Amiq, Geiser, Thomas, Hradetzky, David

Electric 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.

2009, Trebbels, Dennis, Zengerle, Roland, Hradetzky, David

This 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.

2005, Hradetzky, David, Müller, Claas, Reinecke, Holger

This 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 hybridization