Copper tem grids

Copper TEM grids with a mesh size of 400 were purchased from Agar Scientific, including 3 nm amorphous carbon on lacey carbon (AGS187-4), monolayer graphene on holey carbon (AGS179-GO4), and plain holey carbon (AGS174-3). A graphene oxide layer was added to the latter by plasma-cleaning for five minutes, drop casting a 3 μL graphene oxide suspension (763705-25ML, Sigma Aldrich), diluted in water to 0.2 mg mL⁻¹, blotting with filter paper (11547873, Fisherbrand) after one minute, followed by three washing and blotting steps with water. No further treatment was applied to the grids before deposition.

Diblock copolymer dispersions were diluted to generate 0.01 wt% dispersions. Copper TEM grids (Agar Scientific, UK) were surface-coated in-house to yield a thin film of amorphous carbon. Each diblock copolymer dispersion was placed onto a grid and the solvent allowed to evaporate slowly at room temperature. To stain the deposited nanoparticles, the grids were exposed to ruthenium(iv) oxide vapor for 7 min at 20 °C prior to analysis.44 This heavy metal compound acted as a positive stain to improve contrast. The ruthenium(iv) oxide was prepared as follows: ruthenium(ii) oxide (0.30 g) was added to water (50 g) to form a black slurry; addition of sodium periodate (2.0 g) with stirring produced a yellow solution of ruthenium(iv) oxide within 1 min. Imaging was performed at 100 kV using a Phillips CM100 instrument equipped with a Gatan 1k CCD camera. Number-average particle size distributions were obtained by measuring the area of at least 100 nanoparticles and then calculating a histogram with 5 nm wide bins using ImageJ 1.51p.72 (link) These histograms were then fit to a Gaussian distribution.

Copper TEM grids with mesh size 400 were purchased from Agar Scientific, including 3 nm amorphous carbon on a lacey carbon film (AGS187-4) and holey carbon film (AGS174-3). A graphene oxide layer was added to the latter by plasma cleaning for 5 minutes, drop casting of 3 µL graphene oxide suspension (763705-25ML, Sigma-Aldrich), diluted in water to 0.2 mg/mL, blotting with filter paper (11547873, Fisherbrand) after 1 minute, followed by three washing and blotting steps with water. No further treatment was applied to grids before deposition.
The control sample for β-gal was prepared using ammonium acetate solutions used for native ES-IBD and a Cu 200 mesh grid (Q2100CR2, Quantifoil) with 2 µm holes and 2 µm spacing between the holes. Three microliters of a 5 µM solution was applied to the grid, followed by blotting and plunging into liquid ethane, using a Vitrobot (Thermo Fisher Scientific) at a relative humidity of 100% and a temperature of 10°C.