Figure 2.

Characterization of AuNPs-PEI

(A) TEM images of AuNPs-PEI before centrifugation.

(B) TEM images of AuNPs-PEI after resuspension. It was observed that the AuNPs-PEI had uniform particle size and good dispersibility after resuspension. The centrifugal resuspension operation did not cause its agglomeration.

(C) UV absorption peaks of AuNPs-PEI did not shift significantly before centrifugation and after resuspension.

(D) The particle size distribution of AuNPs-PEI before centrifugation. Data were represented as means ± SD from three repeats.

(E) The particle size distribution of AuNPs-PEI after resuspension. Data were represented as means ± SD from three repeats.

(F) The average particle size of AuNPs-PEI before centrifugation and after resuspension. Data were represented as means ± SD from three repeats.

(G) The color change of AuNPs-PEI solution before centrifugation (left) and after resuspension (right). The AuNPs-PEI resuspended after centrifugation and the color was still ruby red, indicating that no coagulation had occurred.