Dapi containing antifade mounting medium

After plating on the coverslips, cells were treated with Cy5-labeled 13-nm, 50-nm or AuNS nanoconstructs which had the similar density of RNA strands (0.21, 0.19 and 0.18 molecules nm⁻² for 13-nm spheres, 50-nm spheres and 40-nm stars, respectively). After 2 h or 24 h incubation, the coverslips were washed 3 times with PBS, fixed with 4% paraformaldehyde and permeabilized with 0.1% Triton X100. Cells were incubated with the blocking solution (1% BSA and 10% rabbit serum in PBS) at room temperature for 1 h. Cells were then incubated at 4 °C overnight with a solution of primary antibodies (mouse anti-human LAMP-1 antibody and goat anti-human EEA-1 antibody; 300-fold dilutions of stocks from Santa Cruz Biotechnology) in blocking solution. After overnight incubation, coverslips were washed 6 times with PBST (0.1% Tween 20 in PBS) over 1 h. Secondary antibodies (rabbit anti-mouse IgG (H + L) Alexa Fluor 488 and rabbit antigoat IgG (H + L) Alexa 594, Thermo) in blocking solution were incubated with the cells for 1 h at room temperature. Following an additional 6 washes with PBST buffer over 1 h, coverslips were mounted on glass slides using DAPI-containing antifade mounting medium (Invitrogen).