An Electrochemical Genosensor for a Fragment of Apolipoprotein E gene based on Reduced Graphene and Cerium Oxide Nanocomposite

A genosensor was fabricated for detecting a fragment of apolipoprotein e gene (apoe). the sensor was made of a nanocomposite of reduced graphene oxide (rgo) and cerium oxide (ceo_2) nanoparticles. for this purpose, surface of a glassy carbon electrode was first modified by polyaniline (pani) and then rgo-ceo_2 nanocomposite. it was next characterized through scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. a 23-base oligonucleotide sequences previously reported as a fragment of apolipoprotein e gene (apoe) which has a point mutation occurred in the progression of alzheimer’s disease was selected as a target molecule. its ssdna probe was immobilized on the modified surface via a strong interactions between ceo_2 nanoparticles and the phosphate groups in the ssdna. detection of the biosensor signal was performed by square wave voltammetry (swv) and ru(bpy)_3]^2+/3+ as an electrochemical probe. in presence and absence of the target sequence, the electrochemical probe showed a different behaviour on the electrode surface. the developed genosensor could detect the apoe gene sequence high selectively and sensitively, with in a good linear range of 10 fm to 10 nm.