Journal of Colloid and Interface Science ( IF 9.4 ) Pub Date : 2022-05-22 , DOI: 10.1016/j.jcis.2022.05.123 Rita Argenziano 1 , Maria Laura Alfieri 1 , Youri Arntz 2 , Rachele Castaldo 3 , Davide Liberti 1 , Daria Maria Monti 1 , Gennaro Gentile 3 , Lucia Panzella 1 , Orlando Crescenzi 1 , Vincent Ball 2 , Alessandra Napolitano 1 , Marco d'Ischia 1
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Hypothesis
The possibility to use hexamethylenediamine (HMDA) to impart film forming ability to natural polymers including eumelanins and plant polyphenols endowed with biological activity and functional properties has been recently explored with the aim to broaden the potential of polydopamine (PDA)-based films overcoming their inherent limitations. 5,6-dihydroxyindole-2-carboxylic acid, its methyl ester (MeDHICA) and eumelanins thereof were shown to exhibit potent reducing activity.
Experiments
MeDHICA and HMDA were reacted in aqueous buffer, pH 9.0 in the presence of different substrates to assess the film forming ability. The effect of different reaction parameters (pH, diamine chain length) on film formation was investigated. Voltammetric and AFM /SEM methods were applied for analysis of the film redox activity and morphology. HPLC, MALDI-MS and 1HNMR were used for chemical characterization. The film reducing activity was evaluated in comparison with PDA by chemical assays and using UV stressed human immortalized keratinocytes (HaCat) cells model.
Findings
Regular and homogeneous yellowish films were obtained with moderately hydrophobic properties. Film deposition was optimal at pH 9, and specifically induced by HMDA. The film consisted of HMDA and monomeric MeDHICA accompanied by dimers/small oligomers, but no detectable MeDHICA/HMDA covalent conjugation products. Spontaneous assembly of self-organized networks held together mainly by electrostatic interactions of MeDHICA in the anion form and HMDA as the dication is proposed as film deposition mechanism. The film displayed potent reducing properties and exerted significant protective effects from oxidative stress on HaCaT.
中文翻译：
氧化还原活性薄膜的非共价小分子伙伴关系：超越聚多巴胺技术
假设
最近探索了使用六亚甲基二胺 (HMDA) 赋予具有生物活性和功能特性的天然聚合物（包括真黑素和植物多酚）成膜能力的可能性，旨在拓宽基于聚多巴胺 (PDA) 的薄膜克服其固有的潜力限制。5,6-二羟基吲哚-2-羧酸、其甲酯 (MeDHICA) 及其真黑素显示出有效的还原活性。
实验
MeDHICA 和 HMDA 在不同底物存在下在 pH 9.0 的水性缓冲液中反应，以评估成膜能力。研究了不同反应参数（pH、二胺链长）对成膜的影响。伏安法和 AFM / SEM 方法用于分析薄膜的氧化还原活性和形态。HPLC、MALDI-MS和1 HNMR用于化学表征。通过化学测定和使用紫外线应激的人永生化角质形成细胞 (HaCat) 细胞模型，与 PDA 相比，评估了膜还原活性。
发现
获得了具有适度疏水性的规则和均匀的黄色薄膜。薄膜沉积在 pH 9 时是最佳的，并且特别是由 HMDA 诱导的。该薄膜由 HMDA 和单体 MeDHICA 组成，并伴有二聚体/小寡聚体，但没有可检测到的 MeDHICA/HMDA 共价结合产物。自组织网络的自发组装主要通过阴离子形式的 MeDHICA 和作为双阳离子的 HMDA 的静电相互作用被提出作为薄膜沉积机制。该薄膜显示出有效的还原特性，并对 HaCaT 的氧化应激产生显着的保护作用。
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