title: Adsorption of amino acids by fullerenes and fullerene nanowhiskers.
abstract: We have investigated the adsorption of some amino acids and an oligopeptide by fullerene (C60) and fullerene nanowhiskers (FNWs). C60and FNWs hardly adsorbed amino acids. Most of the amino acids used have a hydrophobic side chain. Ala and Val, with an alkyl chain, were not adsorbed by the C60or FNWs. Trp, Phe and Pro, with a cyclic structure, were not adsorbed by them either. The aromatic group of C60did not interact with the side chain. The carboxyl or amino group, with the frame structure of an amino acid, has a positive or negative charge in solution. It is likely that the C60and FNWs would not prefer the charged carboxyl or amino group. Tri-Ala was adsorbed slightly by the C60and FNWs. The carboxyl or amino group is not close to the center of the methyl group of Tri-Ala. One of the methyl groups in Tri-Ala would interact with the aromatic structure of the C60and FNWs. We compared our results with the theoretical interaction of 20 bio-amino acids with C60. The theoretical simulations showed the bonding distance between C60and an amino acid and the dissociation energy. The dissociation energy was shown to increase in the order, Val < Phe < Pro < Asp < Ala < Trp < Tyr < Arg < Leu. However, the simulation was not consistent with our experimental results. The adsorption of albumin (a protein) by C60showed the effect on the side chains of Try and Trp. The structure of albumin was changed a little by C60. In our study Try and Tyr were hardly adsorbed by C60and FNWs. These amino acids did not show a different adsorption behavior compared with other amino acids. The adsorptive behavior of mono-amino acids might be different from that of polypeptides.
authors.affiliation: National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Hashizume
authors.affiliation: National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan.
authors.forename: Chika
authors.initials: C
authors.lastname: Hirata
authors.affiliation: National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan.
authors.forename: Kazuko
authors.initials: K
authors.lastname: Fujii
authors.affiliation: National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan.
authors.forename: Kun'ichi
authors.initials: K
authors.lastname: Miyazawa
keywords: adsorption; amino acid; fullerene; fullerene nanowhisker