Abstract

To interact with different biologic systems for biomedical applications, chemical modification of carbon
nanotubes is always a key step. Disulfide is sensitive to the reductive intracellular environment, and such
stimulus-responsive covalent bonds were used to modify carbon nanotubes. After deprotection of
N-tert-butoxycarbonyl (Boc) groups of the N-(tert-butyloxycarbonyl) cystamine modified multi-walled carbon
nanotubes (MWNTs), positively charged ammonium (NH3
+) functionalized MWNTs (MWNTs-S-S-NH3
+) with
disulfide linkages were obtained. Their surface functional groups and changes of morphologies were
characterized by infrared (IR) spectroscope and transmission electron microscope (TEM), respectively. The
weight percentage of the immobilized disulfide was estimated by thermogravimetric analysis (TGA). And their
cytotoxicity in vitro on cultured human nasopharyngeal SUNE1 cells was evaluated. The biocompatibility of
MWNTs was improved compared to that of MWNTs without functional groups.

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