1. Electrospun nanofibers at University of Helsinki
Dr. Antti Laukkanen
DDTC
Drug Discovery and Development Technology Center

2. Cell Culture Models On filter, for example Toropainen et al.:
Culture model of human corneal epithelium for prediction of ocular drug absorption
More difficult with other cell types which need truly 3D environment
Toropainen E, Ranta VP, Talvitie A, Suhonen P, Urtti A: Invest Ophthalmol Vis Sci., 2001, 42,

3. Extra Cellular Matrix – Should we try to mimic it?
Griffith L. and Swartz M., Nature Reviews, 216 (7), 2006

4. Advanced matrices
Schematic drawing of an artificial mimic of an extracellular matrix. The fibrillar skeleton is composed of electrospun biodegradable polymer fibers. The matrix is modified by incorporating cell adhesion ligands on the surface of nanofibers to improve the cell attachment. Hydrophilicity is increased with grafted polymer chains and the cell culturing is controlled with a controlled release of growth factors.

5. Advanced matrices Electrospinning of functional polymers
Post-modification with peptides or direct solid phase synthesis

6. Functional polymers and functional fibers
What is the needed functionality?
Fiber should be cross-linkable or water insoluble
g, UV, or plasma treatment
What other solvents should be tolerated?

7. Fibers for solid phase synthesis
Need for highly stable amino functionalized polymer
Should tolerate DMF and NMP
Synthesis route of amino-functional poly(styrene). The amino-modification could be conducted before or after the electrospinning.
The role 1,4 diaminobutane is twofold: first it will provide the needed amino-functionality on the fibers and secondly it will slightly cross-link the nanofibers. The degree of cross-linking is dependent on the relative amounts of diamine and chloromethyl functionality in the modification reaction.

8. Electrospinning InstrumentationV
Polymer solution
Needle
High voltage power supply
Collector +
Taylor cone
Simplified set-up

9. The Electrospinning device

10. PVP Nanofibers
Pore size mm

11. PEVA Nanofibers Water insoluble – stable in physiological conditions
Fiber diameter 1 -2 mm, pore size mm
Easily modified via hydroxyl group
Possibility to graft other chains by redox polymerization