Effect of BSA on carbon nanotube dispersion for in vivo and in vitro studies

Carbon nanotubes (CNT) are one of the most promising nanomaterials because of their intrinsic properties. So, it becomes urgent to assess their toxicity. However, CNT are insoluble in aqueous media required for toxicological studies. Thus, we propose a simple method to disperse CNT for toxicological studies using a biomolecule: The albumin. To evaluate this method, several nanotubes were suspended in saline solution (NaCl 0.9%) without or with albumin at a concentration of 0.5 mg/ml or equal as CNT concentration. These suspensions were visually compared to suspensions obtained with classical dispersing methods using Tween 80 or serum. Homogeneity of the suspensions with or without BSA and CNT structure were analyzed by TEM, agglomerates quantification and total carbon dosage. The effect of coupled albumin-CNT was then tested on A549 and U937 cells in vitro and on rats in vivo. Total carbon dosage, agglomerates quantification and TEM revealed that, in the presence of albumin, the tested nanotubes were better dispersed without any modification of their structure. The CNT suspension was tested in vitro and in vivo in rats. Albumin solution alone induced no modification of the biological responses studied (i.e., cell viability in vitro and inflammatory response and histopathology in vivo) compared to the saline. CNT in NaCl or BSA altered cellular viability in vitro in a similar way but results obtained with CNT suspension in the presence of albumin showed a better reproducibility that can be explained by the better homogeneity of the suspensions. CNT in BSA but not in NaCl significantly increased the cell number in BAL and also the number of apparent CNT-containing cells. Taken together, these results highlight the potential importance of CNT dispersion (and thus of the vehicle) for the toxicological studies.