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.
Highlights
There is little information available of functionalizing multi-walled carbon nanotubes (MWNTs) in literature for the purpose of conjugating biomolecules onto CNTs conveniently as well as releasing these molecules smartly
We studied the toxicity effects of MWNT-S-S-NH3+ on human nasopharyngeal SUNE1 cells by MTT assay which was used to determine cell survival in the past few years
Morphology and nano-structures of pristine MWNTs, MWNTs-S-S-NH3+ are obserbed by Transmission electron microscopy (TEM) which are shown in Figure 3, TEM observations give definitive proof of the presence of MWNTs-S-S-NH3+ in the solution
Summary
All solvents and reagents were purchased from commercially available sources and used without further purification unless otherwise stated. The MWNTs (98%, 40-60 nm outside diameters, 5-15 μm lengths ) were purchased from Shenzhen Nanotech Port Co., Ltd. Fourier transform infrared (FT-IR) spectra were recorded on a Nicolet 6700 IR spectroscopy. Transmission electron microscopy (TEM) images were acquired on a JEOL JEM-1230 electron microscopy at an accelerating voltage of 100 kV. Thermal gravimetric analysis (TGA) was carried out on a Diamond TG-DTA 6300 instrument in flowing Argon at a heating rate of 10 °C /min from room temperature to 600 oC
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