Biophysical Society Thematic Meeting - October 25-30, 2015

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.

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