A New Electrochemical Sensor for the Simultaneous Determination of Guanine and Adenine: Using NiAl-Layered Double Hydroxide/Graphene Oxide-Multiwall Carbon Nanotubes Modified Glassy Carbon Electrode,B. Rezaei, Hossein Khosropour, Ali A. Ensafi, Moham

 An  electrochemical  sensor  was  developed  for  guanine  (GA)  and  adenine  (AD)
detection using multiwall carbon nanotubes (MWCNTs) with the hybrid of NiAl-layered double
hydroxide/Graphene oxide (NiAl-LDH/GO) on  a  glassy  carbon electrode (GCE) referred to  as
MWCNTs/NiAl-LDH/GO/GCE. The modified electrode was used for the simultaneous detection
of  GA  and  AD.  Electrochemical  performances  related  to  the  direct  electroxidation  of  GA  and
AD  at  the  modified  electrode  were  investigated,  showing  that  their  peak  currents  were  greatly
enhanced due to the presence of MWCNTs/NiAl-LDH/GO nanohybrids. Also, it was revealed
that  the  oxidation  peak  potentials  of  GA  and  AD  on  the  modified  electrode  were  negatively
shifted, leading to the increase of their electrocatalytic activity at the surface of MWCNTs/NiAl-
LDH/GO/GCE. The effects of different parameters such as pH, accumulation time, accumulation
potential, and scan rate on the sensitivity were investigated too. Determination of purine bases
was  done  by  linear  sweep  voltammetric  (LSV)  technique.  The  linear  ranges  of  0.010-45  µM,
with the detection limit of 3 nM   for GA, and 0.08-45 µM, with the detection limit of 20 nM   for
AD,  were  achieved.  Finally,  the  proposed  electrochemical  sensor  was  employed  for  the
simultaneous  determination  of  GA  and  AD  in  single-strand  deoxyribonucleic  acid  (ssDNA)
samples.