TY  - JOUR
A1  - Neffe, Axel T.
A1  - von Rüsten-Lange, Maik
A1  - Braune, Steffen
A1  - Lützow, Karola
A1  - Roch, Toralf
A1  - Richau, Klaus
A1  - Jung, Friedrich
A1  - Lendlein, Andreas
T1  - Poly(ethylene glycol) grafting to Poly(ether imide) membranes - influence on protein adsorption and Thrombocyte adhesion
JF  - Macromolecular bioscience
N2  - The chain length and end groups of linear PEG grafted on smooth surfaces is known to influence protein adsorption and thrombocyte adhesion. Here, it is explored whether established structure function relationships can be transferred to application relevant, rough surfaces. Functionalization of poly(ether imide) (PEI) membranes by grafting with monoamino PEG of different chain lengths (M-n=1kDa or 10kDa) and end groups (methoxy or hydroxyl) is proven by spectroscopy, changes of surface hydrophilicity, and surface shielding effects. The surface functionalization does lead to reduction of adsorption of BSA, but not of fibrinogen. The thrombocyte adhesion is increased compared to untreated PEI surfaces. Conclusively, rough instead of smooth polymer or gold surfaces should be investigated as relevant models.
KW  - biomaterials
KW  - poly(ethylene glycol)
KW  - protein adsorption
KW  - surface functionalization
KW  - thrombocyte adhesion
Y1  - 2013
U6  - https://doi.org/10.1002/mabi.201300309
SN  - 1616-5187
SN  - 1616-5195
VL  - 13
IS  - 12
SP  - 1720
EP  - 1729
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Wang, Li
A1  - Baudis, Stefan
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Characterization of bi-layered magnetic nanoparticles synthesized via two-step surface-initiated ring-opening polymerization
JF  - Pure and applied chemistry : official journal of the International Union of Pure and Applied Chemistry
N2  - A versatile strategy to integrate multiple functions in a polymer based material is the formation of polymer networks with defined nanostructures. Here, we present synthesis and comprehensive characterization of covalently surface functionalized magnetic nanoparticles (MNPs) comprising a bi-layer oligomeric shell, using Sn(Oct)(2) as catalyst for a two-step functionalization. These hydroxy-terminated precursors for degradable magneto-and thermo-sensitive polymer networks were prepared via two subsequent surfaceinitiated ring-opening polymerizations (ROPs) with omega-pentadecalactone and e-caprolactone. A two-step mass loss obtained in thermogravimetric analysis and two distinct melting transitions around 50 and 85 degrees C observed in differential scanning calorimetry experiments, which are attributed to the melting of OPDL and OCL crystallites, confirmed a successful preparation of the modified MNPs. The oligomeric coating of the nanoparticles could be visualized by transmission electron microscopy. The investigation of degrafted oligomeric coatings by gel permeation chromatography and H-1-NMR spectroscopy showed an increase in number average molecular weight as well as the presence of signals related to both of oligo(omega-pentadecalactone) (OPDL) and oligo(e-caprolactone) (OCL) after the second ROP. A more detailed analysis of the NMR results revealed that only a few.-pentadecalactone repeating units are present in the degrafted oligomeric bi-layers, whereby a considerable degree of transesterification could be observed when OPDL was polymerized in the 2nd ROP step. These findings are supported by a low degree of crystallinity for OPDL in the degrafted oligomeric bi-layers obtained in wide angle X-ray scattering experiments. Based on these findings it can be concluded that Sn(Oct)(2) was suitable as catalyst for the preparation of nanosized bi-layered coated MNP precursors by a two-step ROP.
KW  - degradable polyester
KW  - magnetic nanoparticles
KW  - nanoparticle characterization
KW  - NICE-2014
KW  - ring opening polymerization
KW  - surface functionalization
Y1  - 2015
U6  - https://doi.org/10.1515/pac-2015-0607
SN  - 0033-4545
SN  - 1365-3075
VL  - 87
IS  - 11-12
SP  - 1085
EP  - 1097
PB  - De Gruyter
CY  - Berlin
ER  -