Anhydrid-Funktionalisierung von Polystyren

Transcription

1 Anhydrid-Funktionalisierung von Polystyren Strategien zur berflächenmodifizierung von Zellkulturträgern Mirko Nitschke Leibniz Institut für Polymerforschung Dresden Max Bergmann Zentrum für Biomaterialien

2 - intention and background of the study - approches to anhydride functionalization of polymer surfaces - evaluating the results regarding the density of functional groups technical feasibility and simplicity of the approaches additional features accessible with particular approaches only

3 Why anhydride surface functionalization? platform technology : - bind proteins without activation steps - reversibly switch between covalent / non-covalent attachment - can be combined with lateral structuring on the scale of cells

4 Why anhydride surface functionalization? platform technology : - bind proteins without activation steps - reversibly switch between covalent / non-covalent attachment - can be combined with lateral structuring on the scale of cells 20 m K. Lehmann, M. Herklotz, M. Espig, T. Paumer, M. Nitschke, C. Werner, and T. Pompe, A new approach to biofunctionalisation and micropatterning of multi-well plates", Biomaterials 31, 8802

5 Low pressure plasma devices

6 Low pressure plasma devices

7 Low energy electron beam device energy 150 kev, range in polymers 200 m absorbed dose kgy

8 Materials MA PVMEMAc PVMEMA PEMAc PEMA

9 Surface analysis: XPS XPS C 1s XPS instrument (Kratos Amicus)

10 Surface analysis: FTIR-ATR FTIR C= str. anhydride C= str. acid

11 Surface modification strategies

12 a) Maleic anhydride plasma reaction hydrolysis XPS C 1s FTIR

13 b) Plasma immobilization of PVMEMAc XPS C 1s FTIR annealing

14 c) Electron beam immobilization of PEMAc XPS C 1s FTIR annealing

15 d) UV Immobilization of PEMAc-BP CH 2 CH 2 CH CH + m H 2 + n NH 2 CH CH CH 2 CH 2 n CH CH CH 2 CH 2 m NH H H H Synthesis of poly(ethene-alt-maleic acid / (4-benzophenone) maleic amid).

16 d) UV Immobilization of PEMAc-BP FTIR annealing

17 e) Grafting PEMAc to plasma activated surfaces XPS C 1s fluorescence labeling 5-aminofluorescein annealing

18 Comparison / Conclusions Concerning the simplicity of the procedure process (a) is the most favorable one. Anhydride moieties are formed straightforward in a single step. No thin film preparation from polymer solution is required. Regarding the complexity of the set-up (i.e. the cost of the apparatus) the UV technique (d) outperforms any high vacuum (a,b,e) and electron beam based approach (c). The density of anhydride groups that can be obtained by the variety of processes is limited for different reasons. While it is difficult to further improve the structure retention in process (a) the yield of the annealing step in process (b-e) could be increased to almost 100 % when using a temperature of 120 C instead of 90 C (possible in case of materials with a better thermal stability than polystyrene). Beyond the reactivity for binding functional molecules, a well-defined mechanical stiffness of the surface is a key feature of advanced cell culture carriers. Here, process (c) and (d) have the best potential to form soft and swellable hydrogel-like surfaces more than a few nanometers thick.

19 Comparison / Conclusions Using simple masking techniques, all processes allow for lateral microstructuring with a feature size on the typical scale of adherent cells. MA copolymer immobilization (b-e) allows in principle to tune further surface properties (e.g. hydrophilicity) by the choice of the second comonomer unit. However, using another molecular structure may impair the cross-linking efficiency by whatever type of energetic irradiation (ions, electrons or photons) and has to be evaluated for each particular copolymer. While (c) and (d) can be carried out as an in line process, high vacuum techniques (a,b,e) are batch processes on principle.

20 Acknowledgement Special thanks to: S.Gramm, S. Zschoche, M. Herklotz, and S. Ricciardi Thank you for your attention!