Cytotoxicity studies of protein-stabilized fluorescent gold nanoclusters on human lymphocytes.

In this work, we clearly focus on the comparative cytotoxicity investigations of several protein-stabilized gold nanoclusters (Au NCs) towards lymphocytes B (COLO-720 L) and lymphocytes T (HUT-78) cells. For synthesis, the one-pot template-assisted method was carried out using lysozyme (LYZ), human (HSA) and bovine (BSA) serum albumins, and gamma globulin (γG) as stabilizing agents. Regardless of the type of proteins, all synthesized Au NCs possess intense red emission (λem ∼ 650 nm) and have similar size of a metal core (ca. 1.4 nm) with negative surface charge at pH = 7.4. During the treatment of cells with clusters, changes in mitochondrial activity, membrane integrity, secretion of inflammatory and apoptosis mediators of the lymphocytes were studied to determine the potential effect of protein layers on the toxicity of clusters. It was found that γG-Au NCs induced the highest disorders in mitochondrial activity, but the influence of other NCs on the cell viability was minor. Besides, all Au NCs caused oxidative stress by peroxidation of membrane lipids. The secretion of malonic dialdehyde (MDA) was enhanced by LYZ- and γG-Au NCs. Apart from LYZ-Au NCs, the clusters did not exhibit strong proinflammatory and apoptotic properties. The enhanced secretion of tumor necrosis factor (TNF-α) by lymphocytes B, in comparison to control, was independent of the clusters type. Despite the lack of significant influence of the Au NCs on the viability of the lymphocytes, they can stimulate undesirable cellular processes, which clearly depends on the stabilizing proteins.