Cytotoxicity of functionalized carbon nanotubes in J774A macrophages

Cytotoxicity of carbon nanotubes (CNTs) is a prime concern for its use as antigen carriers. Here we evaluated the cytotoxic effect of unpurified (UP-CNTs), purified (P-CNTs), fluorescein isothiocyanate–functionalized (FITC-CNTs), and Entamoeba histolytica 220-kDa lectin–functionalized CNTs (L220-CNTs) in J774A macrophage (MOs) cell line. Cell viability and apoptosis were analyzed by MTT and TUNEL assays, respectively. Cyclooxygenase-2 (COX-2) was analyzed by reverse transcription–polymerase chain reaction. Cytotoxicity at 6.0 mg/L was higher with UP-CNTs > P-CNTs > FITC-CNTs, showing a decrease in cell viability and an increase in apoptosis. In contrast, MOs interacted with L220-CNTs showed an increase in cell viability without signs of apoptosis. Although UP-CNTs and P-CNTs exhibited COX-2 induction with 6.0 mg/L, functionalized CNTs were able to induce COX-2 at concentrations as low as 0.06 mg/L. These results suggest that functionalization decreases toxicity, and that L220-CNTs may be an excellent candidate for the production of a nanovaccine against amebiasis.From the Clinical EditorCytotoxicity of carbon nanotubes may significantly limit their use as delivery systems. This study demonstrates that functionalization of these nanoparticles actually greatly reduces toxicity in J774A macrophages, and that lectin-functionalization may be a viable approach for the production of anti-amebiasis nanovaccines utilizing carbon nanotubes.

Graphical AbstractViability of macrophages interacted with carbon nanotubes (CNTs) at different concentrations at 24 hours. Each bar represents mean ± SD of two experiments done in triplicates (n = 6). a, P < 0.01 denotes significant differences between mean values measured in the indicated group as compared to control without stimulus (CTL). b, P < 0.01 denotes differences between mean values for CNTs at different concentrations. c, P < 0.01 denotes differences between mean values for a particular concentration among different CNTs. CNT-FITC, fluorescein isothiocyanate–functionalized CNTs; CNT-L220, Entamoeba histolytica-220 kDa lectin–functionalized CNTs; P, purified; UP, unpurified.Figure optionsDownload high-quality image (150 K)Download as PowerPoint slide