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Polymers and Self Assembly: From Biology to Nanomaterials Poster Session II
23-POS
Board 23
Self-Assembled Diphenylalanine Modified with Microperoxidase-11 and Glucose Oxidase:
Electrochemical Studies Aiming Sensing Applications
Sergio Kogikoski Jr
1
, Camila Pinheiro de Sousa
1
, Tarciso Andrade Filho
2
, Alexandre R.
Rocha
2
, Suchismita Guha
3
, Wendel A. Alves
1
.
1
Universidade Federal do ABC, Santo André, São Paulo, Brazil,
2
Universidade Estadual Paulista,
São Paulo, São Paulo, Brazil,
3
University of Missouri, Columbia, MO, USA.
Ever since the discovery of L,L-diphenylalanine micro/nanostructures(FF-MNSs), researchers
have been exploring their potential for biosensing purposes. A novel platform for the detection of
glucose was obtained by self-assembly of PAH, FF-MNSs, MP11, and GOx onto glassy
carbon(GC) electrode surface. The peptide nanostructures were prepared by crystallization of the
L,L-diphenylalanine in water, with posterior thermal treatment to obtain different crystal
structure (
P6
1
and
P22
1
2
1
). The peptides were then modified in solution and used to modify
electrodes. The interaction between the FF-MNSs and MP11 was studied by SEM, XRD,
Raman, FTIR and EPR spectroscopy. The electroactive area was studied, and the results showed
an increase in electroactive area due to the use of FF-MNSs. The charge transfer resistance was
studied by electrochemical impedance spectroscopy. The electrodes modified only with the
peptides, GC/(Hex+PAH) and GC/(Ort+PAH), had a resistance of 280 and 102Ω, respectively.
With MP11 modification, the values changed to 506 and 142Ω, respectively. The band structure
of the peptides were calculated and showed that the band-gap energies of the hexagonal is
around 3.6eV, and for the orthorhombic this value is larger around 4.0eV. However, the structure
of the HOMO and LUMO levels of the orthorhombic structure allows it to be doped, similar to
the semi-conductors, and we believe that PAH is acting as dopant for the orthorhombic FF-
MNSs, leading to a smaller charge transfer resistance. The electron transfer rate(k
s
) were studied
using Laviron’s equations, and the values for the electrodes modified with the FF-MNSs were
higher than the one containing only MP11. Our results show that the energy band-gap of the
orthorhombic FF-MNS nanostructures plays a fundamental role in the conductivity and electron
transfer rates when modified with MP11. The efficacy as H
2
O
2
and glucose sensors was also
evaluated.