Klosterman Luke, Bettinger Christopher J
Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
Int J Mol Sci. 2016 Dec 22;18(1):14. doi: 10.3390/ijms18010014.
The facile preparation of conformal polydopamine (PDA) films on broad classes of materials has prompted extensive research into a wide variety of potential applications for PDA. The constituent molecular species in PDA exhibit diverse chemical moieties, and therefore highly variable properties of PDA-based devices may evolve with post-processing conditions. Here we report the use of redox-inactive cations for oxidative post-processing of deposited PDA films. PDA films incubated in alkaline CaCl₂ solutions exhibit accelerated oxidative evolution in a dose-dependent manner. PDA films incubated in CaCl₂ solutions exhibit 53% of the oxidative charge transfer compared to pristine PDA films. Carboxylic acid groups generated from the oxidation process lower the isoelectric point of PDA films from pH = 4.0 ± 0.2 to pH = 3.1 ± 0.3. PDA films exposed to CaCl₂ solutions during post-processing also enhance Fe/Fe chelation compared to pristine PDA films. These data illustrate that the molecular heterogeneity and non-equilibrium character of as-deposited PDA films afford control over the final composition by choosing post-processing conditions, but also demands forethought into how the performance of PDA-incorporated devices may change over time in salt solutions.
在多种材料上轻松制备保形聚多巴胺（PDA）薄膜，这促使人们对PDA的各种潜在应用展开了广泛研究。PDA中的组成分子种类具有多样的化学基团，因此基于PDA的器件的性质可能会随着后处理条件的变化而发生很大改变。在此，我们报道了使用氧化还原惰性阳离子对沉积的PDA薄膜进行氧化后处理。在碱性CaCl₂溶液中孵育的PDA薄膜呈现出剂量依赖性的加速氧化演变。与原始PDA薄膜相比，在CaCl₂溶液中孵育的PDA薄膜表现出53%的氧化电荷转移。氧化过程中产生的羧酸基团将PDA薄膜的等电点从pH = 4.0 ± 0.2降低至pH = 3.1 ± 0.3。与原始PDA薄膜相比，后处理过程中暴露于CaCl₂溶液的PDA薄膜也增强了Fe/Fe螯合作用。这些数据表明，沉积的PDA薄膜的分子异质性和非平衡特性使得通过选择后处理条件能够控制最终组成，但同时也需要预先考虑掺入PDA的器件在盐溶液中的性能会如何随时间变化。
