[1] Univ Basel, Inst Phys Chem, Dept Chem, CH-4058 Basel, Switzerland
[2] Dept Biosyst Sci & Engn, ETH Zurich, CH-4058 Basel, Switzerland
[3] Natl Ctr Competence Res NCCR, Mol Syst Engn, CH-4058 Basel, Switzerland
[4] Swiss Nanosci Inst, CH-4056 Basel, Switzerland