The Shell Thickness of Polydopamine Nanocapsules Influences Protein Adsorption and Cellular Uptake

This work explores the relationship between the thickness of the shell of polydopamine (PDA) nanocapsules, their protein adsorption, and subsequent cellular uptake. Increasing the polymerization time of dopamine from 3 to 144 h (PCF3-PCF144) on a fructose-curcumin (CCM) template increased the capsule size from 106 to 134 nm, as measured by electron microscopy. XPS analysis revealed slight changes in the surface composition following prolonged dopamine deposition. Analysis of the protein corona using fluorescent techniques and liquid chromatography-tandem mass spectrometry (LC-MS/MS) showed that the PDA nanocapsule obtained at the shortest polymerization time (PCF3) adsorbed the most proteins and had the greatest variety, with globin and albumin being abundant. PCF3 also exhibited the highest cellular uptake in three cell lines─the breast cancer cell line MCF-7, bovine aorta endothelial cells, and the macrophage cell line RAW 264.7─while thicker shells resulted in decreased uptake. This work emphasizes that the protein corona can confer colloidal stability in serum and enhance cellular uptake.