Impact of gold nanoparticle coating on redox homeostasis

Gold nanoparticles (AuNP) hold great potential for biomedical applications. This study was aimed at examination of the effect of AuNP coating on the redox status of their environment. Two kinds of AuNP were tested, similar by shape and size, but with different surface coatings: either stabilized with citrate or functionalized with dihydrolipoic acid (Au@DHLA NP). Interestingly, whereas citrate-stabilized AuNP interact in vitro with reduced glutathione (GSH) and S-nitrosoglutathione, Au@DHLA NP do not interfere with both biomolecules. Albumin exhibits higher affinity toward citrate-stabilized AuNP than Au@DHLA NP, increasing their hydrodynamic diameter (8.0- and 1.3-fold, respectively). Furthermore, the AuNP coating affects also their internalization by macrophages (which was two fold higher for citrate-stabilized AuNP), following an exposure to a subtoxic NP concentration (10 nM, 80% viability). Citrate-stabilized AuNP were found to decrease the intracellular GSH level (ca. 20%), with no increase in reactive oxygen species production. Furthermore, these AuNP did not induce apoptosis (as shown by caspase-3 activity and nfkb2 transcription factor), and also did not activate gene expression related to oxidative stress (ncf1) and inflammatory response (tnfα). The present data highlight that the functionalization of AuNP with DHLA decreases their reactivity with biomolecules and cells, resulting in a promising medical platform.