Fig. 4. SEM images of PSI@ZIF-8 coated with 1, 2 and 3 cycles of ZnAc and Hmim treatments (scale bar 1 μm). Corresponding samples which have been washed with SDS and then with ethanol are pictured on the right of each case; (a) 1 cycle leaves PSI accessible to both SDS and EtOH; (b) 2 cycles protect PSI from SDS but not from a smaller organic solvent like EtOH; (c) 3 cycles protect PSI from both, where EtOH removes less than 1% of the original PSI content.