Physics and Astronomy, Faculty of Physical Sciences and Engineering, University of Southampton, Southampton SO171BJ, United Kingdom.
College of Engineering and Technology, American University of the Middle East, Kuwait City, 15453, Kuwait.
Bioconjug Chem. 2022 Jan 19;33(1):219-225. doi: 10.1021/acs.bioconjchem.1c00540. Epub 2022 Jan 9.
Nanoparticles coated with oligonucleotides, also termed spherical nucleic acids (SNAs), are at the forefront of scientific research and have been applied and for sensing, gene regulation, and drug delivery. They demonstrate unique properties stemming from the three-dimensional shell of oligonucleotides and present high cellular uptake. However, their resistance to enzymatic degradation is highly dependent on their physicochemical characteristics. In particular, the oligonucleotide loading of SNAs has been determined to be a critical parameter in SNA design. In order to ensure the successful function of SNAs, the degree of oligonucleotide loading has to be quantitatively determined to confirm that a dense oligonucleotide shell has been achieved. However, this can be time-consuming and may lead to multiple syntheses being required to achieve the necessary degree of surface functionalization. In this work we show how this limitation can be overcome by introducing an oligonucleotide modification. By replacing the phosphodiester bond on the oligonucleotide backbone with a phosphorothioate bond, SNAs even with a low DNA loading showed remarkable stability in the presence of nucleases. Furthermore, these chemically modified SNAs exhibited high selectivity and specificity toward the detection of mRNA .
寡核苷酸修饰的纳米颗粒，也称为球形核酸（SNAs），处于科学研究的前沿，已应用于传感、基因调控和药物传递等领域。它们具有独特的性质，源于寡核苷酸的三维壳，并具有高细胞摄取率。然而，它们对酶降解的抗性高度依赖于它们的物理化学特性。特别是，SNAs 的寡核苷酸负载已被确定为 SNA 设计的关键参数。为了确保 SNAs 的成功功能，必须定量确定寡核苷酸的负载程度，以确认已实现密集的寡核苷酸壳。然而，这可能很耗时，并且可能需要多次合成才能达到必要的表面功能化程度。在这项工作中，我们展示了如何通过引入寡核苷酸修饰来克服这一限制。通过用硫代磷酸酯键替代寡核苷酸主链上的磷酸二酯键，即使 DNA 负载低的 SNAs 在存在核酸酶的情况下也表现出显著的稳定性。此外，这些化学修饰的 SNAs 对 mRNA 的检测表现出高选择性和特异性。
