Multiple spectroscopic studies on the interaction of BSA with pristine CNTs and their toxicity against Donax faba

Enhanced biomedical applications of carbon nanotubes (CNTs) have necessitated the need for the fundamental understanding behind their interaction with biomolecules. Carbon nanotube bundles were dispersed with tween 20 to attain individual nanotubes that are active in UV-vis region. Plasmon resonance of dispersions was obtained at 252 nm of 4.88 eV. FT-Raman bands of dispersions of SWCNTs and MWCNTs at 1346 and 1573 cm(-1) corresponds to the existence of Disordered and Graphitic band of CNTs after dispersion. XRD revealed crystalline feature of graphitic structures of CNTs. SEM-EDAX showed tubular structures of CNTs along with the existence of lower percentage contents of metal impurities. Hyperchromic effect of BSA-CNT complex suggested the existence of ground state complex between them. Quenching nature of CNTs against the intrinsic fluorescence potential of BSA followed static mechanism. 3D fluorescence spectra of BSA confirmed the possibilities of their binding with CNTs via tryptophan and tyrosine residues, followed by the disturbances to their aromatic environment. Alterations were observed in the amide band position of FTIR spectra of BSA-CNT conjugates. Loss of alpha-helical structures and alteration in the tryptophan position were evidenced with respect to CD spectra. The toxicity profile of pristine and BSA-CNT conjugates were evaluated against Donax faba. On comparison with pristine CNTs, BSA-CNTs conjugates showed higher LC50 dose values. In addition, the histopathology of the tissues, treated with CNT-BSA conjugates has shown decreased effect on the cellular integrity rather than the pristine ones. Hence, the adsorption of biomolecules such as the proteins over CNTs surface could have possible effect on reducing their toxicity profile in nature. (C) 2015 Elsevier B.V. All rights reserved.