TY  - JOUR
A1  - Schulz, Anita
A1  - Jaksch, Sebastian
A1  - Schubel, Rene
A1  - Wegener, Erik
A1  - Di, Zhenyu
A1  - Han, Yingchao
A1  - Meister, Annette
A1  - Kressler, Jörg
A1  - Kabanov, Alexander V.
A1  - Luxenhofer, Robert
A1  - Papadakis, Christine M.
A1  - Jordan, Rainer
T1  - Drug-Induced Morphology Switch in Drug Delivery Systems Based on Poly(2-oxazoline)s
JF  - ACS Nano
N2  - Defined aggregates of polymers such as polymeric micelles are of great importance in the development of pharmaceutical formulations. The amount of drug that can be formulated by a drug delivery system is an important issue, and most drug delivery systems suffer from their relatively low drug-loading capacity. However, as the loading capacities increase, i.e., promoted by good drug–polymer interactions, the drug may affect the morphology and stability of the micellar system. We investigated this effect in a prominent system with very high capacity for hydrophobic drugs and found extraordinary stability as well as a profound morphology change upon incorporation of paclitaxel into micelles of amphiphilic ABA poly(2-oxazoline) triblock copolymers. The hydrophilic blocks A comprised poly(2-methyl-2-oxazoline), while the middle blocks B were either just barely hydrophobic poly(2-n-butyl-2-oxazoline) or highly hydrophobic poly(2-n-nonyl-2-oxazoline). The aggregation behavior of both polymers and their formulations with varying paclitaxel contents were investigated by means of dynamic light scattering, atomic force microscopy, (cryogenic) transmission electron microscopy, and small-angle neutron scattering. While without drug, wormlike micelles were present, after incorporation of small amounts of drugs only spherical morphologies remained. Furthermore, the much more hydrophobic poly(2-n-nonyl-2-oxazoline)-containing triblock copolymer exhibited only half the capacity for paclitaxel than the poly(2-n-butyl-2-oxazoline)-containing copolymer along with a lower stability. In the latter, contents of paclitaxel of 8 wt % or higher resulted in a raspberry-like micellar core.
KW  - amphiphilic poly(2-oxazoline)s
KW  - paclitaxel
KW  - drug delivery
KW  - rod-to-sphere transition
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-120766
N1  - This is an open access article published under an ACS AuthorChoice License (http://pubs.acs.org/page/policy/authorchoice_termsofuse.html), which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
VL  - 8
IS  - 3
ER  - 
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  -