New MWCNT-Fe3O4@PDA-Ag nanocomposite as a novel sensing element of an electrochemical sensor for determination of guanine and adenine contents of DNA

Herein, we report a facile approach to prepare an MWCNT-Fe3O4@PDA-Ag nanocomposite that can act toward purine bases. The nanocomposite was characterized with Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The characterization results showed that Ag nanoparticles were well anchored onto the polydopamine (PDA) cover of the MWCNT-Fe3O4@PDA nanocomposite. The produced nanocomposite was successfully incorporated as the heart of a sensing element to design a novel electrochemical sensor for individual or simultaneous determination of guanine (G) and adenine (A). The sensor showed an excellent electrocatalytical function toward determination of G and A. The oxidation peak currents were linear over the concentration ranges of 8-130 and 10-120 mu M for G and A, respectively. The lower detection limits of the sensor were estimated to be 1.47 mu M for G and 5.66 mu M for A. The MWCNT-Fe3O4@PDA-Ag nanocomposite based sensor was successfully applied to detect G and A in fish sperm DNA sample. (C) 2015 Elsevier B.V. All rights reserved.