Adsorption of Adenine, Cytosine, Thymine, and Uracil on Sulfide-Modified Montmorillonite: FT-IR, Mossbauer and EPR Spectroscopy and X-Ray Diffractometry Studies
Adsorption of Adenine, Cytosine, Thymine, and Uracil on Sulfide-Modified Montmorillonite: FT-IR, Mossbauer and EPR Spectroscopy and X-Ray Diffractometry Studies
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DOI：
10.1007/s11084-011-9244-3
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发表时间：
2011-10-01
影响因子：
2
通讯作者：
Zaia, Dimas A. M.
中科院分区：
文献类型：
--
作者：
Carneiro, Cristine E. A.;Berndt, Graciele;Zaia, Dimas A. M.
在ph值为2.00和7.00的条件下，采用不同的技术研究了核酸碱基与粘土的相互作用和吸附。穆斯堡尔光谱和EPR光谱以及x射线衍射显示，本工作最重要的发现是核酸碱基渗透到粘土层间，将Fe2+氧化为Fe3+，因此，这种相互作用不能看作是简单的物理吸附。对于这两种ph，核酸碱基在粘土上的吸附顺序为：腺嘌呤近似于胞嘧啶b>胸腺嘧啶b>尿嘧啶。随着ph的降低，腺嘌呤和胞嘧啶在粘土上的吸附量增加。对于未改变的蒙脱土，这一结果可以解释为带正电的腺嘌呤/胞嘧啶与带负电的粘土之间的静电力。然而，对于Na2S修饰的蒙脱土，可能范德华力也起重要作用，因为腺嘌呤/胞嘧啶和粘土都带正电。红外光谱显示，核酸碱基与粘土的相互作用主要是通过NH+或NH2+基团进行的。x射线衍射图显示，吸附在粘土上的核酸碱基分布在层间表面、边缘位置和外表面官能团（铝醇、硅醇）中。EPR谱图显示，近似于2的线g强度增加可能是由于核酸碱基将Fe2+氧化为Fe3+，而g=4.1线强度增加可能是由于Fe3+与核酸碱基的相互作用。穆斯堡尔光谱显示，由于核酸碱基与Fe2+的反应，粘土的Fe2+双重态面积明显减小。
In the present work the interactions of nucleic acid bases with and adsorption on clays were studied at two pHs (2.00, 7.00) using different techniques. As shown by Mossbauer and EPR spectroscopies and X-ray diffractometry, the most important finding of this work is that nucleic acid bases penetrate into the interlayer of the clays and oxidize Fe2+ to Fe3+, thus, this interaction cannot be regarded as a simple physical adsorption. For the two pHs the order of the adsorption of nucleic acid bases on the clays was: adenine approximate to cytosine>thymine>uracil. The adsorption of adenine and cytosine on clays increased with decreasing of the pH. For unaltered montmorillonite this result could be explained by electrostatic forces between adenine/cytosine positively charged and clay negatively charged. However for montmorillonite modified with Na2S, probably van der Waals forces also play an important role since both adenine/cytosine and clay were positively charged. FT-IR spectra showed that the interaction between nucleic acid bases and clays was through NH+ or NH2+ groups. X-ray diffractograms showed that nucleic acid bases adsorbed on clays were distributed into the interlayer surface, edge sites and external surface functional groups (aluminol, silanol) EPR spectra showed that the intensity of the line g approximate to 2 increased probably because the oxidation of Fe2+ to Fe3+ by nucleic acid bases and intensity of the line g=4.1 increased due to the interaction of Fe3+ with nucleic acid bases. Mossbauer spectra showed a large decreased on the Fe2+ doublet area of the clays due to the reaction of nucleic acid bases with Fe2+.