High-Resolution Imaging of Polyethylene Glycol Coated Dendrimers via Combined Atomic Force and Scanning Tunneling Microscopy

Figure 3

Height characterization of dendrimers without and with PEGylation via nanoshaving. (a) A 300 × 300 nm² AFM topographic image of a nanoshaved monolayer of G4-PAMAM-NH₂. The (a) inset is a 1.5 × 1.5 m AFM topographic image of the G4-PAMAM-NH₂ surface where a 0.5 × 0.5 m area was removed during nanoshaving to reveal the Au substrate. (b) A 400 × 400 nm² AFM topographic image of a nanoshaved monolayer of G4-PAMAM-50PEG₁₀₀₀. The (b) inset is a 1.5 × 1.5 m AFM topographic image of the G4-PAMAM-50PEG₁₀₀₀ surface where a 0.5 × 0.5 m area was removed during nanoshaving to reveal the Au substrate. Cursor 1 reveals the height of individual G4-PAMAM-NH₂ from image (a). From left to right, the gold substrate (gold), dendrimers displaced during nanoshaving (grey), and the dendrimer monolayer (blue). Cursor 2 reveals the height of individual G4-PAMAM-50PEG₁₀₀₀ from image (b). From left to right, the gold substrate (gold), dendrimers displaced during nanoshaving (grey), and the dendrimer monolayer (red).