Síntese e caracterização de nanotubos de carbono de acesso restrito magnéticos e seu uso para extração de Cu e Zn de Cu, Zn- superóxido dismutase

Abstract

In this paper we propose new sorbents denominated magnetic restricted access carbon nanotubes (M-RACNTs) and obtained by the association of magnetic carbon nanotubes (MCNTs) with restricted access carbon nanotubes (RACNTs). The synthesis was carried out covering M-CNTs with a bovine serum albumin (BSA) layer, chemically crosslinked by using glutaraldehyde. The BSA capsule acts as a biocompatible barrier that avoids the bind of proteins from the sample. In pH larger than the isoelectrical point of proteins, both proteins from the sample and from the BSA layer are negatively charged, resulting in exclusion by electrostatic repulsion. This new sorbent can be efficiently used in dispersive solid phase extraction of metals from biological fluids, excluding simultaneously all the proteins from samples. M-RACNTs were characterized by Fourier-transform infrared spectroscopy, thermogravimetric analysis and transmission electron microscopy, being confirmed the presence of the Fe2O3 magnetic nanoparticles as well as the BSA layer on the CNTs. The kinect tests were carried out by sorption of Cu and Zn in CNTs, M-CNTs and M-RACNTs, and the results confirmed the fast and similar mass transference speed for all the sorbents. The adsorption tests confirmed that Cu and Zn ions are retained in monolayers, according to the Sips model. Additionally, the maximum adsorption capacities for Cu and Zn sorption in CNTs, M-CNTs and M-RACNTs had an average of 80,83 mg g-1. M-RACNTs was able to remove of about 64% of Cu and Zn from Cu,Zn-superoxide dismutase with only one dispersive solid phase extraction step. At the same time, the sorbent was able to exclude of about 98% of Cu, Zn-superoxide dismutase. Based on these results, we believe the M-RACNTs are promising sorbents for dispersive solid phase extraction of metals directly from protein fluids objecting the obtaining of apoproteins as well as for extraction of metals or organic compounds directly from biological fluids, with analytical interest.