A comparative evaluation of oxidative chemical modifications on MWCNTs surfaces

Oxidized carbon nanotubes (CNTs) exhibit interesting properties applicable in the biosensor and biomedical fields. In this work, oxidation of multi-walled carbon nanotubes (MWCNTs) was studied using various oxidizing reagents, and the gamut for generating carboxylic functional groups required for the derivatization of MWCNTs has been evaluated. The physicochemical properties of the obtained oxidized MWCNTs were evaluated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetry, potentiometric titration, and BSA protein immobilization study. The gradation in the efficacies of oxidizing reagents to generate carboxylic function at the MWCNTs surface, derived on the basis of FTIR spectroscopy, thermogravimetry, and potentiometric titration, was shown to be in agreement with the gradation in BSA protein immobilization. The results present a fundamental understanding of the oxidation process of MWCNTs and their derivatization with bioactive molecules applicable in biomedical sciences.