Tem grid

The carbon-coated TEM grids (Ted Pella, USA) were treated using a glow discharge device Emitech K100X (Quorum Technologies, UK) to hydrophilise the carbon surface and increase the adsorption. The exosomes were deposited onto the grids for 3 min, contrasted with 1% uranyl acetate, and dried. Imaging was carried out using a JEM-1011 (Jeol, Japan) transmission electron microscope at 80 kV.

Low resolution transmission electron microscopy (TEM) was performed on a JEOL 200 CX microscope. TEM grids were purchased from Ted Pella, Inc. and consisted of 3–4 nm amorphous carbon film supported on a 400-mesh copper grid.

Binary SLs were prepared by means of a drying-mediated
approach, whereby the NC solution was slowly evaporated over a tilted
support. TEM grids (F/C-coated, Ted Pella, with the Formvar layer
removed by immersing the grid in toluene for 10 s) or SiN membranes
(Agar Scientific, Norcada) were employed as the substrates. A coassembly
was carried out by placing the NC mixture in toluene (30–35
μL) into a 2 mL vial with solid support inside. The vial was
then positioned tilted in the vacuum chamber (pressure ∼0.5
bar, room temperature), where it was left until all solvent evaporated.
The mixtures contained overall NC concentrations in the 0.8–1
μM range. For binary ABO₆-type SL, 5.3 nm CsPbBr₃ NCs (9.6 μM, 3 μL), 17.6 nm CsPbBr₃ NCs (0.9 μM, 4 μL), and anhydrous toluene (25 μL)
were used. For NaCl-type SL, a lower small-to-large NC number ratio
was employed: 5.3 nm CsPbBr₃ NCs (9.6 μM, 2 μL),
17.6 nm CsPbBr₃ NCs (1.3 μM, 6.2 μL), and anhydrous
toluene (25 μL). For binary ABO₃-type SL, larger
8.0 nm CsPbBr₃ NCs (10.1 μM, 3 μL) were utilized
together with 17.6 nm CsPbBr₃ NCs (1.1 μM, 5 μL),
and anhydrous toluene (25 μL).

The phase and crystallinity of the Bi_2−xSb_xTe₃ NWs were characterized by X-ray diffraction (XRD) with a Bruker D8 diffractometer (Bruker AXS, Madison, WI, USA) equipped with Lynx Eye position-sensitive detector using Cu Kα radiation (λ = 1.5418 Åu) at room temperature. Peak shifts due to sample misalignment were adjusted while performing the XRD scans and background correction was taken care of by using a zero diffraction silicon substrate for mounting. Microstructural studies were carried out by field–emission scanning electron microscopy (FE–SEM, FEI Nova NanoSEM, FEI, USA) and transmission electron microscopy (HRTEM, JEOL 4000EXII, JEOL, Tokyo, Japan). For TEM analysis Bi_2−xSb_xTe₃ NWs were released and collected by dissolving the PC templates in chlorobenzene (99%, Sigma Aldrich) followed by centrifugation. The NWs were then dispersed in anhydrous ethanol and drop-cast onto TEM grids (Ted Pella Inc., Redding, CA, USA). Energy Dispersive X-ray Analysis (EDX, Oxford Instruments, Oxfordshire, UK) was carried out to map the elemental distribution and to scan the elemental distribution along individual Bi_2−xSb_xTe₃ NWs. Structural studies such as XRD and SEM were also carried out on the NWs freed from the template.