Department of Chemistry and Waterloo Institute for Nanotechnology, University Of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Langmuir. 2012 Oct 9;28(40):14330-7. doi: 10.1021/la302799s. Epub 2012 Sep 28.
Understanding the interface between DNA and nanomaterials is crucial for rational design and optimization of biosensors and drug delivery systems. For detection and delivery into cells, where high concentrations of cellular proteins are present, another layer of complexity is added. In this context, we employ polyethylene glycol (PEG) as a model polymer to mimic the excluded volume effect of cellular proteins and to test its effects on DNA adsorption and hybridization on gold nanoparticles (AuNPs) and graphene oxide (GO), both of which show great promise for designing intracellular biosensors and drug delivery systems. We show that PEG 20000 (e.g., 4%) accelerates DNA hybridization to DNA-functionalized AuNPs by 50-100%, but this enhanced hybridization kinetics has not been observed with free DNA. Therefore, this rate enhancement is attributed to the surface blocking effect by PEG instead of the macromolecular crowding effect. On the other hand, DNA adsorption on citrate-capped AuNP surfaces is impeded even in the presence of a trace level (i.e., parts per billion) of PEG, confirming PEG competes with DNA for surface binding sites. Additional insights have been obtained by studying the adsorption of a thiolated DNA and a peptide nucleic acid. In these cases, the steric effects of PEG to impede adsorption are observed. Similar observations have also been made with GO. Therefore, PEG may be used as an effective blocking agent for both hydrophilic AuNP and for GO that also contains hydrophobic domains.
理解 DNA 和纳米材料之间的界面对于合理设计生物传感器和药物输送系统至关重要。对于检测和输送到细胞中，由于存在高浓度的细胞蛋白，因此又增加了另一层复杂性。在这种情况下，我们使用聚乙二醇（PEG）作为模型聚合物来模拟细胞蛋白的排除体积效应，并测试其对金纳米粒子（AuNPs）和氧化石墨烯（GO）上 DNA 吸附和杂交的影响，这两者都为设计细胞内生物传感器和药物输送系统提供了很大的希望。我们表明，PEG 20000（例如 4％）可将 DNA 与 DNA 功能化的 AuNP 的杂交加速 50-100％，但这种增强的杂交动力学并未在游离 DNA 中观察到。因此，这种速率增强归因于 PEG 的表面阻塞效应而不是大分子拥挤效应。另一方面，即使存在痕量（即十亿分之几）PEG，柠檬酸封端的 AuNP 表面上的 DNA 吸附也受到阻碍，这证实了 PEG 与 DNA 竞争表面结合位点。通过研究巯基化 DNA 和肽核酸的吸附，我们获得了更多的见解。在这些情况下，观察到 PEG 的空间位阻效应对吸附的阻碍。在 GO 中也观察到了类似的观察结果。因此，PEG 可用作亲水 AuNP 和同时包含疏水域的 GO 的有效封闭剂。
