Eclipse ni u upright optical microscope

HepG2 cells were seeded on a pretreated coverslip (22 × 22 mm²) in culture dishes at density of 1 × 10⁵ and cultured overnight. After the culture medium was abandoned, GNCs-Pt-ICG/Tf (50 μg/mL) was dispersed in DMEM and incubated with cells for additional 2 h. Then, the uninternalized nanoparticles were washed away with PBS solution (1 mL × 3 times). The uptake of GNCs-Pt-ICG/Tf by HepG2 cells was observed by a Nikon Eclipse Ni-U upright optical microscope. As controls, cell uptake of GNCs-Pt-ICG (without Tf) and GNCs-ICG/Tf (without PtNPs) was also investigated. To assess the specific recognition capability of GNCs-Pt-ICG/Tf, the cell uptake of GNCs-Pt-ICG/Tf and GNCs-Pt-ICG by NCTC1469 cells (a mouse fibroblast cell line) was investigated.

PBS (pH 7.4, 10 mM) and DMEM were used to mimic the human blood plasma environments. GNCs-Pt-ICG/Tf was first mixed with different media (H₂O, PBS, and DMEM) for 30 min. Then, the biological stability of GNCs-Pt-ICG/Tf was investigated by a Nikon Eclipse Ni-U upright optical microscope.