Protein corona modulation of hepatocyte uptake and molecular mechanisms of gold nanoparticle toxicity

Protein corona formation over gold nanoparticles (AuNP) can modulate cellular responses by altering AuNP physicochemical properties. The liver plays an essential role in metabolism, detoxification and elimination of xenobiotics and drugs as well as circulating NP clearance. We investigated human hepatic uptake of 40 and 80 nm AuNP with branched polyethylenimine (BPEI), lipoic acid (LA) and polyethylene glycol (PEG) coatings as well as human plasma protein (HP) and human serum albumin (HSA) coronas. AuNP-mediated cytotoxicity, reactive oxygen/reactive nitrogen species (ROS/RNS), and CYP activity in human hepatocytes as well as molecular mechanisms with 40 nm bare and HP BPEI-AuNP were investigated. Time-dependent increase in uptake occurred for all bare AuNP but HP and HSA decreased uptake except for 40 nm HP PEG-AuNP. BPEI-AuNP showed time-and concentration-dependent increase in ROS/RNS which correlated with cytotoxicity at 24 h. HP corona substantially reduced ROS/RNS. The 40 and 80 nm bare, HP or HSA LA- and PEG-AuNP were not toxic but HP was as cytotoxic as bare BPEI-AuNP. All bare and HP BPEI-AuNP, except for HP 80 nm BPEI-AuNP toward CYP1A2, inhibited CYP1A2, CYP2C9 and CYP3A4 activity. Transcriptional profiling was dose-dependent with 40 nm bare BPEI-AuNP (1.9% genes at IC₁₀ and 18.9% at LC₅₀) and HP (23.5% at LC₅₀). Differentially expressed genes at LC₅₀ were mainly involved in phase I metabolism and phospholipidosis pathways. Cytotoxicity of bare BPEI-AuNP caused an upregulation of antioxidant and pro-apoptotic genes. These studies contribute to a better understanding of the dramatic effect of protein coronas (PC) on AuNP cellular uptake, cytotoxicity and their underlying molecular mechanisms of action.