*2.9. Scanning Electronic Microscopy (SEM)*

Previously plated on glass coverslips, RBL-2H3 cells were exposed to PBS (as negative control) and LiRecTCTP (100 and 200 μg/mL) in Tyrode's Buffer (TGB) for 2 h at 37 ◦C. After, cells were washed with TGB and fixed with Karnovsky (2% formaldehyde, 2.5% glutaraldehyde in 0.1 M of sodium cacodylate buffer pH 7.2 at 4 ◦C) [18]. Then, fixed cells were dehydrated, and critical-point drying was performed using a Balzers CPD-010 (Balzers Instruments, Balzers, Liechtenstein) with carbonic gas. Metallization in gold was performed using a Balzers SCD-030 (Balzers Instruments). The samples were observed and photographed with a JEOL-JSM 6360 LV scanning electron microscope (JEOL Ltd., Tokyo, Japan) at the Electron Microscopy Center, Federal University of Paraná (Curitiba, PR, Brazil).
