Lacey carbon film coating

The Cryo-TEM was conducted following our previously described protocol^{35 (link)}. Briefly, a 3 µL sample of NP in PBS was dispensed onto a glow discharged copper grid (300 mesh) with lacey carbon film coating (ProSciTech, QLD, Australia). The grid was blotted against filter paper (Whatman 541) and plunged into liquid ethane using an in-house plunge freezing device in 80% humidity. The samples were presented to the transmission electron microscope TEM (FEI, Eindhoven, The Netherlands) operated at 120 kV using a Gatan 626 cryo-holder (Gatan, Pleasanton, CA, USA). A low electron dose of 8–10 electrons/Ų was employed. Images were captured using a FEI Eagle 4kx4k CCD camera (FEI) and AnalySIS software v3.2 (Olympus.).

Cyro-transmission electron microscope (TEM) imaging was conducted as described before [10 (link), 18 (link)]. 3 µL of Tf@pSiNPs in PBS were dispensed onto a glow discharged copper grid (300 mesh) with lacey carbon film coating (ProSciTech, Australia). This grid was blotted against Whatman 541 filter paper and emerged into liquid ethane using a plunge freezing device at 80% humidity. These were observed under the TEM (FEI, Netherlands), at 120 kV using a Gatan 626 cryo-holder (Gatan, USA), and a low electron dose of 8–10 electrons/Ų. FEI Eagle 4kx4k CCD camera (FEI, Netherlands) and AnalySIS v3.2 (Olympus) were utilised for imaging.