1. a Interface Biology Group, Department of Physics and Measurement Technology, Linköping Univer-sity, S-58183 Linköping, Sweden
2. b Institute of Surface Chemistry, Stockholm, Sweden
3. c Parmacia/Ophtalmics, Uppsala, Sweden
4. d Academic Hospital, Uppsala, Sweden
5. e Interface Biology Group, Department of Physics and Measurement Technology, Linköping Univer-sity, S-58183 Linköping, Sweden