Effect of gold nanoparticle size and surface coating on human red blood cells

This paper reports the impact of bovine serum albumin (BSA) coating on gold (Au) nanoparticles (NPs) with sizes of 15, 30, 50 and 70 nm on cellular uptake and haemolysis of human red blood cells (RBCs). BSA coating on gold NPs imparts extra stability in high-glutathione-containing medium, which is a major prerequisite for NPs being developed for delivery applications. BSA coating on gold NPs was characterised by Fourier transform infrared spectroscopy, whereas cellular uptake was estimated by ultraviolet–visible spectrophotometry and flow cytometry. The cellular uptake results show that the internalisation of bare gold NPs is size dependent; however, upon BSA conjugation, uptake becomes independent of particle size. Cytocompatibility of bare and BSA-coated gold NPs was assessed by MTT assay, a common method to evaluate the biocompatibility of nanomaterials, and found non-toxic. However, when bare gold NPs were exposed to human RBCs, the NPs exerted significant haemolysis, which suggests that bare gold NPs which are considered as non-toxic to mammalian cells, can be harmful to RBCs. Interestingly, BSA-coated gold NPs showed significantly lower haemolysis at similar concentrations, suggesting that BSA-coated gold NPs could be of great importance in biomedical applications.