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). C60 and 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 C60 or FNWs. Trp, Phe and Pro, with a cyclic structure, were not adsorbed by them either. The aromatic group of C60 did 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 C60 and FNWs would not prefer the charged carboxyl or amino group. Tri-Ala was adsorbed slightly by the C60 and 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 C60 and FNWs. We compared our results with the theoretical interaction of 20 bio-amino acids with C60. The theoretical simulations showed the bonding distance between C60 and 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 C60 showed 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 C60 and 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.

Large-Area Aligned Fullerene Nanocrystal Scaffolds as Culture Substrates for Enhancing Mesenchymal Stem Cell Self-Renewal and Multipotency

“…Protein adsorption on the surface of high-aFNWs was examined by using fluorescent labeled fibronectin. Fullerene could form stable complexes with proteins due to its hydrophobic nature and π-electron-rich system. , On the basis of wettability and nanopatterned structure, and as predicted by the Cassie model, proteins were found to be selectively adsorbed at the ridge surfaces of high-aFNWs (Figure f, Figure S7). Aligned protein nanopatterns were formed on high-aFNWs scaffolds (compared with the glass control; see also Figure S8) demonstrating that a graded alignment of the aligned FNWs nanopattern can be directly translated into finely tuned manipulation of cell–material interactions, thus providing a route to attain an appropriate cell–ECM interaction for hMSC renewal.…”