Faculty of Chemistry, University of Warsaw, 1 Pasteur St., 02-093 Warsaw, Poland.
Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland.
Molecules. 2021 Jul 13;26(14):4246. doi: 10.3390/molecules26144246.
Layers formed from single-stranded DNA on nanostructured plasmonic metals can be applied as "working elements" in surface-enhanced Raman scattering (SERS) sensors used to sensitively and accurately identify specific DNA fragments in various biological samples (for example, in samples of blood). Therefore, the proper formation of the desired DNA layers on SERS substrates is of great practical importance, and many research groups are working to improve the process in forming such structures. In this work, we propose two modifications of a standard method used for depositing DNA with an attached linking thiol moiety on certain SERS-active structures; the modifications yield DNA layers that generate a stronger SERS signal. We propose: (i) freezing the sample when forming DNA layers on the nanoparticles, and (ii) when forming DNA layers on SERS-active macroscopic silver substrates, using -substituted alkanethiols with very short alkane chains (such as cysteamine or mercaptopropionic acid) to backfill the empty spaces on the metal surface unoccupied by DNA. When 6-mercapto-1-hexanol is used to fill the unoccupied places on a silver surface (as in experiments on standard gold substrates), a quick detachment of chemisorbed DNA from the silver surface is observed. Whereas, using -substituted alkanethiols with a shorter alkane chain makes it possible to easily form mixed DNA/backfilling thiol monolayers. Probably, the significantly lower desorption rate of the thiolated DNA induced by alkanethiols with shorter chains is due to the lower stabilization energy in monolayers formed from such compounds.
在纳米结构等离激元金属上形成的单链 DNA 层可用作表面增强拉曼散射 (SERS) 传感器中的“工作元件”，用于在各种生物样品（例如血液样品）中灵敏且准确地识别特定的 DNA 片段。因此，在 SERS 衬底上正确形成所需的 DNA 层具有重要的实际意义，许多研究小组正在努力改进形成此类结构的过程。在这项工作中，我们提出了两种改进标准方法的方法，用于将带有附着的硫醇部分的 DNA 沉积在某些 SERS 活性结构上；这两种修饰方法都能产生更强的 SERS 信号。我们提出：（i）在纳米粒子上形成 DNA 层时冻结样品，以及（ii）在 SERS 活性宏观银衬底上形成 DNA 层时，使用带有非常短的烷烃链的 -取代烷硫醇（例如半胱胺或巯基丙酸）来填充金属表面上未被 DNA 占据的空位。当使用 6-巯基-1-己醇填充银表面上的空位（如在标准金衬底上的实验中）时，观察到化学吸附的 DNA 从银表面快速脱附。相比之下，使用带有较短烷烃链的 -取代烷硫醇更容易形成混合 DNA/填充硫醇单层。可能是由于形成这些化合物的单层的稳定能较低，导致具有较短链的烷硫醇诱导的硫代 DNA 的解吸率显著降低。
