1. School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K.
2. Department of Chemistry, University of Victoria, Victoria, BC V8W 3V6, Canada
3. Centre for Advanced Materials and Related Technology (CAMTEC), University of Victoria, 3800 Finnerty Rd, Victoria, BC, V8P 5C2, Canada
4. Department of Mechanical Engineering, Division of Medical Sciences, University of Victoria, Victoria, BC V8W 2Y2, Canada
5. School of Biomedical Engineering, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
6. Wolfson Bioimaging Facility, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, U.K.
7. School of Biochemistry, University of Bristol, Bristol BS8 1TD, U.K.
8. GW4 Facility for High-Resolution Electron Cryo-Microscopy, 24 Tyndall Ave, Bristol BS8 1TQ, U.K.