One of the key advantages of carbon nanotubes in biomedical applications is that they can be easily internalized by cells, and therefore can act as delivery vehicles for therapeutical and diagnosis purposes. The clinical applications of using carbon nanotubes in medicine will depend on the outcomes of efficacy and Immunotoxicological studies, which will provide the necessary risk-to-benefit assessments for carbon-nanotube based materials. The objective of the present study was to evaluate the in vitro inflammatory properties of single walled carbon nanotubes functionalized with polyethylene glycol (PEG-SWNT). Human monocytic cell line THP-1 was cultured with various concentrations of PEG-SWNT in different time points and the expression of several innate immunity receptor genes as molecular markers of Inflammation was analyzed by real time quantitative PCR (qPCR). In this study the expression of several pattern recognition receptors (PRRs) including TLR2, TLR4, CD14 and adaptor protein MyD88 which are the main sensors of Inflammation was analyzed in the PEG-SWNT treated THP-1 cells. According to our results a significant up-regulation of TLR2, TLR4, CD14 and MyD88 transcripts was observed when THP-1 cells were treated with various concentrations of PEG-SWNT. However, down-regulation of the expression of molecular markers of Inflammation was observed when the cells were treated with high concentrations of PEG-SWNT which might suggest that higher concentrations of PEG-SWNT are toxic for the cells. In conclusion the results presented in this study show that PEG-SWNT could trigger cellular inflammatory responses as shown by the expression analysis of genes involved in innate immunity and inflammation.

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