Surface Science of DNA Adsorption onto Citrate-Capped Gold Nanoparticles
Surface Science of DNA Adsorption onto Citrate-Capped Gold Nanoparticles
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DOI：
10.1021/la205036p
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发表时间：
2012-02-28
期刊：
影响因子：
3.9
通讯作者：
Liu, Juewen
中科院分区：
文献类型：
--
作者：
Zhang, Xu;Servos, Mark R.;Liu, Juewen
单链DNA可以被柠檬酸盐覆盖的金纳米颗粒（AuNP）吸附，从而增加AuNP的稳定性，这形成了许多生化和分析应用的基础，但这种吸附反应的基本相互作用仍不清楚。在这项研究中，我们测量了DNA吸附动力学，容量和等温线，表明吸附过程是由静电力。DNA链之间以及DNA和AuNP之间的电荷排斥可以通过添加盐、降低pH或通过使用不带电荷的肽核酸（PNA）来降低。获得了Langmuir吸附等温线，表明存在DNA从AuNP的吸附和解吸。虽然增加盐浓度有利于DNA吸附，但由于DNA压实，脱附速率也在较高的盐中增强。DNA吸附能力由DNA寡聚体长度、DNA浓度和盐决定。以前的研究表明，短的DNA寡聚体的吸附更快的金纳米粒子，我们发现，一旦吸附，较长的DNA是更有效地保护金纳米粒子从聚集。使用低pH缓冲液和高酒精浓度也有利于DNA吸附。提出了一个基于金纳米粒子静电排斥的模型来合理化DNA吸附/脱附行为。
Single-stranded DNA can be adsorbed by citrate capped gold nanoparticles (AuNPs), resulting in increased AuNP stability, which forms the basis of a number of biochemical and analytical applications, but the fundamental interaction of this adsorption reaction remains unclear. In this study, we measured DNA adsorption kinetics, capacity, and isotherms, demonstrating that the adsorption process is governed by electrostatic forces. The charge repulsion among DNA strands and between DNA and AuNPs can be reduced by adding salt, reducing pH or by using noncharged peptide nucleic acid (PNA). Langmuir adsorption isotherms are obtained, indicating the presence of both adsorption and desorption of DNA from AuNPs. While increasing salt concentration facilitates DNA adsorption, the desorption rate is also enhanced in higher salt due to DNA compaction. DNA adsorption capacity is determined by DNA oligomer length, DNA concentration, and salt. Previous studies indicated faster adsorption of short DNA oligomers by AuNPs, we find that once adsorbed, longer DNAs are much more effective in protecting AuNPs from aggregation. DNA adsorption is also facilitated by using low pH buffers and high alcohol concentrations. A model based on electrostatic repulsion on AuNPs is proposed to rationalize the DNA adsorption/desorption behavior.