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

Figure 5

High-resolution characterization of dendrimers doped at 1 : 70 and 1 : 700 dendrimer to Pt²⁺ molar ratios. (a–c) 15 × 15 nm² STM topographic images of G4-PAMAM-50PEG₁₀₀₀, G4-PAMAM-6PEG₁₀₀₀, and G4-PAMAM-NH₂ doped in a solution containing a 1 : 70 molar ratio of dendrimer to Pt²⁺. (d–f) 15 × 15 nm² STM topographic images of G4-PAMAM-50PEG₁₀₀₀, G4-PAMAM-6PEG₁₀₀₀, and G4-PAMAM-NH₂ doped in a solution containing a 1 : 700 molar ratio of dendrimer to Pt². Cursors 1–3 provide the lateral and apparent height dimensions of individual representative G4-PAMAM-50PEG₁₀₀₀, G4-PAMAM-6PEG₁₀₀₀, and G4-PAMAM-NH₂ dendrimers doped at a 1 : 70 Pt²⁺ ratio. Cursors 4–6 provide the lateral and apparent height dimensions of individual representative G4-PAMAM-50PEG₁₀₀₀, G4-PAMAM-6PEG₁₀₀₀, and G4-PAMAM-NH₂ dendrimers doped at a 1 : 700 Pt²⁺ ratio. All images were acquired at 0.7–0.9 V and 20–30 pA.