Size-dependent cellular toxicity and uptake of commercial colloidal gold nanoparticles in DU-145 cells

Urinary tract infection (UTI) is a predominant condition in prostate cancer patients. Escherichia coli ORN178 (EC-178) is the uropathogen that causes recurrent infection by binding specifically to adhesins of prostate cancer cells (DU-145 cells). Gold nanoparticles (GNPs) have been used in biodiagnosis of pathogens. In this study, we have investigated the binding time of EC-178 to DU-145 cells, the cytotoxicity and uptake of plain and mannose functionalized and 20 and 200 nm GNPs (d-mannan (Mn)-GNPs). We also investigated the protein corona of GNPs when incubated with fetal bovine serum to study the protein corona which decides the biological fate of the GNPs. It was seen that EC-178 binds and is inside the DU-145 cells by 3 h of incubation period. Plain 20 nm GNPs decrease the percentage of viable cells in 48 and 72 h in log and lag phase of DU-145 cells. It was also observed that the Mn-GNPs were taken up by the DU-145 cells significantly more than the plain GNPs. Protein corona was observed when GNPs were incubated with fetal bovine serum which was confirmed by dynamic light scattering measurements and SDS-PAGE gel.