Zandieh Mohamad, Liu Juewen
Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Langmuir. 2020 Mar 31;36(12):3260-3267. doi: 10.1021/acs.langmuir.0c00046. Epub 2020 Mar 18.
Polydopamine (PDA) is a widely used universal coating for a broad range of materials. Interfacing PDA with various biomolecules, such as DNA, is critical for applications such as sensing, intracellular delivery, and material fabrication. Because of the negative surface charge of PDA at neutral pH, electrostatic repulsion exists between PDA and DNA. In previous studies, modified DNA or low pH was used to overcome this repulsion for DNA adsorption. More recently, divalent Ca was found to bridge DNA and PDA. Herein, we studied four transition metals (Mn, Co, Zn, and Ni) and compared their efficiencies with Ca for promoting DNA adsorption. These transition metals induced a more efficient and tighter DNA binding compared to Ca. In all these cases, the DNA phosphate backbone played a dominant role in adsorption, although DNA bases might also interact with strong binding metals such as Ni. Moreover, when the adsorption affinity was stronger, sensing was more selective to complementary DNA. Finally, aging of PDA appeared to be detrimental for DNA adsorption, which could be due to further oxidation of PDA. We showed that using Zn or Ni could considerably relieve the aging effect, while storing PDA at 4 °C could slow down aging.
聚多巴胺（PDA）是一种广泛应用于多种材料的通用涂层。将PDA与各种生物分子（如DNA）连接，对于传感、细胞内递送和材料制造等应用至关重要。由于PDA在中性pH下带负表面电荷，PDA与DNA之间存在静电排斥。在先前的研究中，使用修饰的DNA或低pH来克服这种排斥以实现DNA吸附。最近，发现二价钙可桥接DNA和PDA。在此，我们研究了四种过渡金属（锰、钴、锌和镍），并将它们与钙促进DNA吸附的效率进行了比较。与钙相比，这些过渡金属诱导了更有效且更紧密的DNA结合。在所有这些情况下，DNA磷酸骨架在吸附中起主导作用，尽管DNA碱基也可能与强结合金属（如镍）相互作用。此外，当吸附亲和力更强时，传感对互补DNA更具选择性。最后，PDA的老化似乎对DNA吸附不利，这可能是由于PDA的进一步氧化。我们表明，使用锌或镍可以大大减轻老化效应，而将PDA储存在4°C可以减缓老化。
