Macrophage Inflammatory Response to SelfΑssembling Rosette Nanotubes

Rosette nanotubes (RNTs) are a new class of nanomaterials with significant therapeutic potential. However, societal concerns related to the potential adverse health effects of engineered nanomaterials drew attention towards the investigation of their interaction with the human U937 macrophage cell line. The cells are treated with medium only (control), lysine (50μg mL^-1), lysine-functionalized RNTs (RNT-K; 1, 5, and 50μg mL^-1), Min-U-Sil quartz microparticles (80μg mL^-1), or lipopolysaccharide (1μg mL^-1). The supernatant and cells are assayed for cell viability, cytokine protein, and mRNA expression at 1, 6, and 24 h post-treatment. The results indicate that RNT-K activate transcription of proinflammatory genes (interleukin-8 and tumor necrosis factorΑ (TNFΑ)) within 1 h, but this effect is not accompanied by protein secretion into the supernatant. The effect of the length of RNTs on human U937 macrophage viability is also investigated. Although both short and long RNT-K exhibit time-dependent effects on TNFΑ transcription, only the short RNT-K (5μg mL^-1) increase TNFΑ concentration at 6 h relative to the long RNT-K. Moreover, RNT-K (1 and 5μg mL^-1) have no effect on cell viability by 24 h. These data indicate that RNTK do not induce a robust inflammatory response or cytotoxicity in the U937 human macrophage cell line, and therefore could be used for biomedical applications.