Carbon nanomaterials as drug carriers: Real time drug release investigation

The use of carbon nanomaterials in biomedical applications and the cytotoxicity of these materials have been areas of great interest during the last decade. In vitro drug load and release, as well as in vivo animal tests, have been carried out using carbon nanomaterials. However, no comparison studies on the drug load and the release of different carbon nanomaterials have been reported. Here, we report on a real time investigation of the drug release of carbon black (CB) nanoparticles, carbon nanotubes (CNTs) and graphene oxide (GO), using rhodamine B (RB) as a model of drug. The binding of RB to the nanomaterials were characterized by FTIR and UV-vis. The mass loading capacities of these nanomaterials were also studied, showing that GO had the highest capacity. The real time drug release experiment indicated different accumulative release modes of these nanomaterials at different pH values, due to their different binding modes with RB, which is also discussed as being the reason for the mechanism differences. Moreover, the comparison of the drug release capacity of CNT-RB and f-CNT-RB (functionalized-CNT-RB) indicated an influence of hydrogen bonds in both drug loading and release, as the hydrogen bonds increased the loading capacity of the carbon nanotube after acid treatment and changed the drug release mechanism at pH 7.4. Thus, here we identified the drug release modes of the different carbon nanomaterials. The results of the influence of functional groups and hydrogen bonds point also out a potential way of controlling the drug release behavior of carbon nanomaterials by surface modification. (C) 2012 Elsevier B.V. All rights reserved.