Theoretical evidence for the stronger ability of thymine to disperse SWCNT than cytosine and adenine: Self-stacking of DNA bases vs their cross-stacking with SWCNT
Theoretical evidence for the stronger ability of thymine to disperse SWCNT than cytosine and adenine: Self-stacking of DNA bases vs their cross-stacking with SWCNT
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DOI：
10.1021/jp803917t
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发表时间：
2008-09-18
影响因子：
3.7
通讯作者：
Wang, Yixuan
中科院分区：
文献类型：
--
作者：
Wang, Yixuan
采用一种新的混合密度泛函方法MPWB 1 K/cc-pVDZ，研究了腺嘌呤（A）、胞嘧啶（C）、鸟嘌呤（G）和胸腺嘧啶（T）4种DNA碱基的自堆积以及它们与（5，5）和（10，0）单壁碳纳米管（SWCNTs）的交叉堆积.采用MP2/6-311++G（d，p）方法对气相和水溶液中的结合能进行了修正，其中溶剂效应采用类导体极化连续模型（CPCM）和UAHF半径进行了考虑. G和A的最强自堆积为位移反平行组态，而C和T的最稳定组态为未位移或“重叠”反平行组态。在气相中，碱基的自堆积作用顺序为G > A > C > T。而在水溶液中，由于溶剂效应的不同，它们的自堆积表现出明显的顺序：A > G > T > C。对于给定的碱，在气相和水溶液中，交叉堆积比自堆积强。对于（10，0）和（5，5）SWCNT，气相中交叉堆叠的结合能变化为G > A > T > C，并且四个核碱基与（10，0）的结合比与（5，5）SWCNT的结合略强0.1-0.5 kcal/mol。水溶液中的交叉堆积与气相中的交叉堆积不同：对于（10，0）SWCNT，A > G > T > C;对于（5，5）SWCNT，G > A > T > C。有人建议，核碱基分散单壁碳纳米管的能力取决于相对强度（Δ Δ E-bin（溶胶））的自堆积和交叉堆积与单壁碳纳米管在水溶液中。在四种研究的核碱基中，胸腺嘧啶（T）表现出最高的Δ Δ E-bin（sol），这可以很好地解释T比C和A更有效地官能化SWCNT的实验发现。
Self-stacking of four DNA bases, adenine (A), cytosine (C), guanine (G) and thymine (T), and their cross-stacking with (5,5) as well as (10,0) single walled carbon nanotubes (SWCNTs) were extensively investigated with a novel hybrid DFT method, MPWB1 K/cc-pVDZ. The binding energies were further corrected with MP2/6-311++G(d,p) method in both gas phase and aqueous solution, where the solvent effects were included with conductor-like polarized continuum model (CPCM) model and UAHF radii. The strongest self-stacking of G and A takes displaced antiparallel configuration, but undisplaced or "eclipsed" antiparallel configuration is the most stable for C and T. In gas phase the self-stacking of nucleobases decreases in the sequence G > A > C > T. while because of quite different solvent effects their self-stacking in aqueous solution exhibits a distinct sequence A > G > T > C. For a given base, cross-stacking is stronger than self-stacking in both gas phase and aqueous solution. Binding energy for cross-stacking in gas phase varies as G > A > T > C for both (10,0) and (5,5) SWCNTs, and the binding of four nucleobases to (10,0) is slightly stronger than to (5,5) SWCNT by a range of 0.1-0.5 kcal/mol. The cross-stacking in aqueous solution varies differently from that gas phase: A > G > T > C for (10,0) SWCNT and G > A > T > C for (5,5) SWCNT. It is suggested that the ability of nucleobases to disperse SWCNT depends on relative strength (Delta Delta E-bin(sol)) of self-stacking and cross-stacking with SWCNT in aqueous solution. Of the four investigated nucleobases thymine (T) exhibits the highest Delta Delta E-bin(sol), which can well explain the experimental finding that T more efficiently functionalizes SWCNT than C and A.