Polyethyleneimine-Mediated Functionalization of Multiwalled Carbon Nanotubes: Synthesis, Characterization, and In Vitro Toxicity Assay

Abstract

Polymer-functionalized carbon nanotubes hold great promise for their use in environmental and biomedical applications. In this work, polyethyleneimine (PEI) was covalently bonded to acid-treated multiwalled carbon nanotubes (MWCNTs) through amide bond formation. The amine groups of PEI on the surface of MWCNTs were then reacted with acetic anhydride or succinic anhydride to form MWCNTs with neutral or negative surface charges, respectively. The structural transformation, surface potential, and morphology of the functionalized MWCNTs were characterized by nuclear magnetic resonance, thermogravimetric analysis, zeta potential, and transmission electron microscopy. The functionalized MWCNTs are water-soluble and stable. In vitro cytotoxicity assays using both FRO cells (a human thyroid cancer cell line) and KB cells (a human epithelial carcinoma cell line) reveal that the biocompatibility of these functionalized MWCNTs is largely dependent on their surface potential. Neutral and negatively charged MWCNTs are nontoxic to both cell lines at a concentration up to 100 µg/mL, whereas positively charged MWCNTs are toxic to FRO cells at 10 µg/mL. The results of this study demonstrate that PEI-modified MWCNTs can be chemically modified to alter their surface charges and cytotoxicity, thereby significantly improving the biocompatibility of the materials for a variety of biomedical applications.

Methodological considerations for testing the ecotoxicity of carbon nanotubes and fullerenes: Review

“…Likewise, various types of surface-modified fullerenes have also exhibited substantially different toxicities to Daphnia pulex and Daphnia magna compared with underivatized fullerenes [62,63]. It was shown previously that cellular toxicity varies substantially based on surface coatings or functional groups on the surfaces of CNTs [64,65]. Changes at the cellular level as a result of different surface modifications do not, however, necessarily translate to similar effects in whole organisms.…”

Transport of Surface-modified Carbon Nanotubes through a Soil Column

“…Functionalized CNTs can, however, remain dispersed and stable in aqueous solutions and are used for biomedical purposes such as drug delivery 9 . Here it is essential that the CNTs remain dispersed and mobilized, so the drug can be delivered within the human body 10 .…”

Aminopropyltriethoxysilane-mediated surface functionalization of hydroxyapatite nanoparticles: synthesis, characterization, and in vitro toxicity assay

“…The acetylation reaction was performed according to a procedure described in our previous work. 39 In brief, n-HA-APTS (50 mg) was dispersed thoroughly in dimethylsulfoxide (15 mL) under magnetic stirring, followed by addition of triethylamine (1 mL) and the solution was well mixed for 30 minutes. Excess acetic anhydride (1 mL) dissolved in dimethylsulfoxide (5 mL) was then added dropwise into the n-HA-APTS/triethylamine mixture solution under vigorous magnetic stirring.…”

“…39 Briefly, n-HA-APTS (50 mg) dispersed in dimethylsulfoxide (20 mL) was added with excess succinic anhydride (500 mg) dissolved in 5 mL of dimethylsulfoxide under vigorous magnetic stirring. The reaction was stopped after 24 hours.…”

“…These results are consistent with our previous report. 39 The relatively toxic APTS-modified nanohydroxyapatite particles with surface amine groups should be due to the electrostatic interaction between the positively charged particles and the negatively charged cell membranes. [45][46][47] The neutralization of the surface amine groups to form acetamide or carboxyl groups can significantly …”