Department of Chemical Sciences, University of Naples "Federico II" , Via Cintia 4, I-80126 Naples, Italy.
INM - Leibniz Institute for New Materials , Campus D2 2, 66123 Saarbrücken, Germany.
Langmuir. 2017 Mar 7;33(9):2096-2102. doi: 10.1021/acs.langmuir.6b04079. Epub 2017 Feb 17.
The exploitation of easily accessible and nontoxic natural catechol compounds for surface functionalization and coating is attracting growing interest for biomedical applications. We report herein the deposition on different substrates of chemically stable thin films by autoxidation of 1 mM caffeic acid (CA) solutions at pH 9 in the presence of equimolar amounts of hexamethylenediamine (HMDA). UV-visible, mass spectrometric, and solid state C and N NMR analysis indicated covalent incorporation of the amine during CA polymerization to produce insoluble trioxybenzacridinium scaffolds decorated with carboxyl and amine functionalities. Similar coatings are obtained by replacing CA with 4-methylcatechol (MC) in the presence of HMDA. No significant film deposition was detected in the absence of HMDA nor by replacing it with shorter chain ethylenediamine, or with monoamines. The CA/HMDA-based films resisted oxidative and reductive treatments, displayed efficient Fe(II) and Cu(II) binding capacity and organic dyes adsorption, and provided an excellent cytocompatible platform for growing embryonic stem cells. These results pointed to HMDA as an efficient cross-linking mediator of film deposition from natural catechols for surface functionalization and coatings.
从易于获取且无毒的天然儿茶素化合物中提取的物质，可用于表面功能化和涂层，这一特性使其在生物医学领域的应用受到了越来越多的关注。本文报道了在 pH 值为 9 的条件下，通过 1 mM 没食子酸（CA）溶液的自氧化作用，在等摩尔量的六亚甲基二胺（HMDA）存在下，在不同基底上沉积化学稳定性良好的薄膜的方法。紫外可见光谱、质谱、固态 C 和 N NMR 分析表明，在 CA 聚合过程中，胺通过共价键合掺入，生成带有羧基和胺基官能团的不溶性三氧苯并吖啶酮支架。在 HMDA 存在下，用 4-甲基儿茶酚（MC）代替 CA 也可以得到类似的涂层。在没有 HMDA 存在的情况下，或者用短链乙二胺或单胺代替 HMDA，都不会检测到明显的薄膜沉积。基于 CA/HMDA 的薄膜能抵抗氧化和还原处理，具有高效的 Fe(II)和 Cu(II)结合能力和有机染料吸附能力，为胚胎干细胞的生长提供了一个极好的细胞相容性平台。这些结果表明，HMDA 是一种有效的交联介导物质，可用于从天然儿茶素中提取物质，以实现表面功能化和涂层。
