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Immobilization of Amino Acids Leucine and Glycine on Polypyrrole for Biosensor Applications: A Density Functional Theory Study
Hermawan K. Dipojono1, Nugraha 1, Irma Safitri1, Eko Mursito B.1, Nuryanti1, Adhitya G Saputro1,2, Melanie Y. David2,3 & Hideaki Kasai1,2
1Laboratory of Computational Material Design and Quantum Engineering, Engineering Physics Research Group, Faculty of Industrial Technology, Institut Teknologi Bandung, Jln. Ganesa 10, Bandung 40132, Indonesia
2Division of Precision Science & Technology, and Applied Physics, Osaka University, Suita, Osaka, 565 – 0871, Japan
3 Physics Department, College of Science, De La Salle University, 2401 Taft Ave., Malate, Manila 1004, Philippines
Email :dipojono@tf.itb.ac.id or nugraha@tf.itb.ac.id
Abstract. Adsorption based on the immobilization of amino acids, i.e. leucine and glycine, on the surface of undoped polypyrrole (Ppy) is investigated. Calculations are done based on density functional theory using Gaussian03 software and applying GGA with 6-31G(d) basis set and exchange-correlation model of PBE (Perdew, Burke, Ernzerhof) level of theory. The energy of the Ppy doped with amino acids are minimized with respect to the orientation and distance of the amino acids to the Ppy. Neutral leucine carboxyl shows greater binding energy as compared to that other leucine configurations. It has adsorption energy of 0.25 eV at optimum distance of 2.2 Å from the surface of Ppy. As for the glycine, the zwitterionic carboxyl exhibits the strongest binding energy among other glycine configurations. It has adsorption energy of 0.76 eV at optimum distance of 1.7 Å from the surface of Ppy. The adsorption processes for both amino acids should proceed easily because the activation barriers are either absent or very small.
Keywords: adsorption; density functional theory; glycine; immobilization; leucine; polypyrrole
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