Theoretical Insights into the Interaction Mechanism between Proteins and SWCNTs: Adsorptions of Tripeptides GXG on SWCNTs

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• 作者：Yixuan Wang ; Hongqi Ai
• 刊名：Journal of Physical Chemistry B
• 出版年：2009
• 出版时间：July 16, 2009
• 年：2009
• 卷：113
• 期：28
• 页码：9620-9627
• 全文大小：413K
• 年卷期：v.113,no.28(July 16, 2009)
• ISSN：1520-5207

文摘

Adsorptions of nine tripeptides GXG, ranging from negatively (D) and positively (K) charged, to hydrophilic (N and S), and to hydrophobic (G, V, F, W, and Y) residues, on the two cluster models (C₅₄H₁₈ and C₅₄) of (10,0) single-walled carbon nanotubes (SWCNTs) are systemically investigated with the MPWB1K and MP2 methods. The solvent effects are taken into account with the implicit CPCM model. The objective is to provide novel insights into the interaction mechanism between proteins and SWCNTs. Results reveal that the adsorption strength of two charged tripeptides is greatly affected by the solvent effect and the hydrogen saturability of the SWCNT models. In the gas phase, on the surface of C₅₄H₁₈, GKG has the strongest adsorption (adsorption energy (AE): −29.3 kcal/mol at the MP2 level), whereas the adsorption of the negatively charged GDG is the strongest on C₅₄ (AE: −30.4 kcal/mol with MP2). However, because of strong solvation, the adsorptions of the charged residues (D and K) on both C₅₄H₁₈ and C₅₄ surfaces in aqueous solution are either rather weak or even unbound. The two neutral hydrophilic residues (N and S) exhibit adsorptions on C₅₄H₁₈ in the gas phase (AE: −3.3 and −4.2 kcal/mol), yet are unable to adsorb on SWCNTs in aqueous solution (AE: +0.3 kcal/mol at MP2+CPCM). The five hydrophobic residues present relatively strong adsorption on SWCNTs, especially for the three aromatic residues (GFG, GYG, and GWG), regardless of the CNT model and whether they are in the gas phase or solution. These results indicate that in general the aromatic groups of proteins would play a very important role on functionalizing CNTs, which basically supports the relevant experimental observations. In addition, the electron correlation is essential for adsorptions of GXG on pristine SWCNTs, and the three aromatic residues have the highest electron correlation effects. The present investigation provides strong evidence that for the functionalization of CNTs via proteins it is most likely that hydrophobic interaction and van der Waals are the dominant driving forces.