TY  - JOUR
A1  - Hütten, Mareike
A1  - Dhanasingh, Anandhan
A1  - Hessler, Roland
A1  - Stöver, Timo
A1  - Esser, Karl-Heinz
A1  - Möller, Martin
A1  - Lenarz, Thomas
A1  - Jolly, Claude
A1  - Groll, Jürgen
A1  - Scheper, Verena
T1  - In Vitro and In Vivo Evaluation of a Hydrogel Reservoir as a Continuous Drug Delivery System for Inner Ear Treatment
JF  - PLoS ONE
N2  - Fibrous tissue growth and loss of residual hearing after cochlear implantation can be reduced by application of the glucocorticoid dexamethasone-21-phosphate-disodium-salt (DEX). To date, sustained delivery of this agent to the cochlea using a number of pharmaceutical technologies has not been entirely successful. In this study we examine a novel way of continuous local drug application into the inner ear using a refillable hydrogel functionalized silicone reservoir. A PEG-based hydrogel made of reactive NCO-sP(EO-stat-PO) prepolymers was evaluated as a drug conveying and delivery system in vitro and in vivo. Encapsulating the free form hydrogel into a silicone tube with a small opening for the drug diffusion resulted in delayed drug release but unaffected diffusion of DEX through the gel compared to the free form hydrogel. Additionally, controlled DEX release over several weeks could be demonstrated using the hydrogel filled reservoir. Using a guinea-pig cochlear trauma model the reservoir delivery of DEX significantly protected residual hearing and reduced fibrosis. As well as being used as a device in its own right or in combination with cochlear implants, the hydrogel-filled reservoir represents a new drug delivery system that feasibly could be replenished with therapeutic agents to provide sustained treatment of the inner ear.
KW  - gels
KW  - cochlea
KW  - silicones
KW  - deafness
KW  - inner ear
KW  - drug delivery
KW  - inflammation
KW  - connective tissue
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119375
VL  - 9
IS  - 8
ER  - 
TY  - JOUR
A1  - Brendtke, Rico
A1  - Wiehl, Michael
A1  - Groeber, Florian
A1  - Schwarz, Thomas
A1  - Walles, Heike
A1  - Hansmann, Jan
T1  - Feasibility Study on a Microwave-Based Sensor for Measuring Hydration Level Using Human Skin Models
JF  - PLoS ONE
N2  - Tissue dehydration results in three major types of exsiccosis—hyper-, hypo-, or isonatraemia. All three types entail alterations of salt concentrations leading to impaired biochemical processes, and can finally cause severe morbidity. The aim of our study was to demonstrate the feasibility of a microwave-based sensor technology for the non-invasive measurement of the hydration status. Electromagnetic waves at high frequencies interact with molecules, especially water. Hence, if a sample contains free water molecules, this can be detected in a reflected microwave signal. To develop the sensor system, human three-dimensional skin equivalents were instituted as a standardized test platform mimicking reproducible exsiccosis scenarios. Therefore, skin equivalents with a specific hydration and density of matrix components were generated and microwave measurements were performed. Hydration-specific spectra allowed deriving the hydration state of the skin models. A further advantage of the skin equivalents was the characterization of the impact of distinct skin components on the measured signals to investigate mechanisms of signal generation. The results demonstrate the feasibility of a non-invasive microwave-based hydration sensor technology. The sensor bears potential to be integrated in a wearable medical device for personal health monitoring.
KW  - gels
KW  - microwave radiation
KW  - collagens
KW  - skin physiology
KW  - reflection
KW  - skin anatomy
KW  - epidermis
KW  - antennas
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-179934
VL  - 11
IS  - 4
ER  -