TY  - JOUR
A1  - Lübtow, Michael  M.
A1  - Marciniak, Henning
A1  - Schmiedel, Alexander
A1  - Roos, Markus
A1  - Lambert, Christoph
A1  - Luxenhofer, Robert
T1  - Ultra-high to ultra-low drug loaded micelles: Probing host-guest interactions by fluorescence spectroscopy
JF  - Chemistry - A European Journal
N2  - Polymer micelles are an attractive means to solubilize water insoluble compounds such as drugs. Drug loading, formulations stability and control over drug release are crucial factors for drug‐loaded polymer micelles. The interactions between the polymeric host and the guest molecules are considered critical to control these factors but typically barely understood. Here, we compare two isomeric polymer micelles, one of which enables ultra‐high curcumin loading exceeding 50 wt.%, while the other allows a drug loading of only 25 wt.%. In the low capacity micelles, steady‐state fluorescence revealed a very unusual feature of curcumin fluorescence, a high energy emission at 510 nm. Time‐resolved fluorescence upconversion showed that the fluorescence life time of the corresponding species is too short in the high‐capacity micelles, preventing an observable emission in steady‐state. Therefore, contrary to common perception, stronger interactions between host and guest can be detrimental to the drug loading in polymer micelles.
KW  - curcumin
KW  - drug delivery
KW  - fluorenscence
KW  - poly(2-oxazine)
KW  - pol(2-oxazoline)
KW  - Polymer-drug interaction
KW  - upconversion
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-206128
VL  - 25
IS  - 54
ER  - 
TY  - JOUR
A1  - Lübtow, Michael M.
A1  - Lorson, Thomas
A1  - Finger, Tamara
A1  - Gröber-Becker, Florian-Kai
A1  - Luxenhofer, Robert
T1  - Combining Ultra-High Drug-Loaded Micelles and Injectable Hydrogel Drug Depots for Prolonged Drug Release
JF  - Macromolecular Chemistry and Physics
N2  - Hydrogel‐based drug depot formulations are of great interest for therapeutic applications. While the biological activity of such drug depots is often characterized well, the influence of incorporated drug or drug‐loaded micelles on the gelation properties of the hydrogel matrix is less investigated. However, the latter is of great importance from fundamental and application points of view as it informs on the physicochemical interactions of drugs and water‐swollen polymer networks and it determines injectability, depot stability, as well as drug‐release kinetics. Here, the impact of incorporated drug, neat polymer micelles, and drug‐loaded micelles on the viscoelastic properties of a cytocompatible hydrogel is investigated systematically. To challenge the hydrogel with regard to the desired application as injectable drug depot, curcumin (CUR) is chosen as a model compound due to its very low‐water solubility and limited stability. CUR is either directly solubilized by the hydrogel or pre‐incorporated into polymer micelles. Interference of CUR with the temperature‐induced gelation process can be suppressed by pre‐incorporation into polymer micelles forming a binary drug delivery system. Drug release from a collagen matrix is studied in a trans‐well setup. Compared to direct injection of drug formulations, the hydrogel‐based systems show improved and extended drug release over 10 weeks.
KW  - curcumin
KW  - drug depots
KW  - drug-loaded hydrogels
KW  - poly(2-oxazine)
KW  - sustained release
KW  - poly(2- oxazoline)
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-208115
VL  - 221
IS  - 1
ER  -