Fig. 3

Variations of N2a cell membrane roughness under the treatment of AuNPs. a Bright-field reflection image and the topography of N2a cells measured by NIWOP. Data was recorded before and after 4 h of treatments. In each condition, the regions marked by the white square in the bright field images are displayed in the membrane topography. b SEM images of the N2a cells. The samples were measured after the treatment for 4 h. The yellow squares mark large aggregations of the AuNPs. c Statistics of N2a cell membrane roughness. The blue bars are measured before the treatment and the red bars are measured after 4 h of treatment. The cell number for the PAH-AuNPs and Bare-AuNPs group is 23 and 25, respectively. Data show the mean ± standard deviation. ***, p < 0.005 (Student’s t test)