Vitiello Giuseppe, Zanfardino Anna, Tammaro Olimpia, Di Napoli Michela, Caso Maria Federica, Pezzella Alessandro, Varcamonti Mario, Silvestri Brigida, D'Errico Gerardino, Costantini Aniello, Luciani Giuseppina
Department of Chemical, Materials and Production Engineering, University of Naples Federico II p.le V. Tecchio 80 80125 Naples Italy
CSGI, Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase Via della Lastruccia 3 50019 Florence Italy.
RSC Adv. 2018 Aug 7;8(50):28275-28283. doi: 10.1039/c8ra04315a.
Intrinsic biocide efficacy of eumelanins can be markedly enhanced through a templated formation in the presence of a TiO-sol, leading to hybrid TiO-melanin nanostructures. However, mechanisms and processes behind biocide activity still remain poorly understood. This paper discloses the fundamental mechanism of action of these systems providing mechanistic information on their peculiar interaction with strains. To this purpose biocide characterization is combined with Electron Paramagnetic Resonance (EPR) spectroscopy to investigate radical species produced by the hybrids as well as their interactions with Gram(-) external bacterial membranes. Experimental results indicate that TiO mediated eumelanin polymerization leads to a peculiar mechanism of action of hybrid nanostructures, whose strong interactions with bacterial membranes enhance the action of reactive oxygen species (ROS) produced by eumelanin degradation itself, also concurring with the final biocide action. These findings provide strategic information for the development of eumelanin-based systems with enhanced activity against drug-resistant strains.
通过在二氧化钛溶胶存在下的模板化形成，真黑素的固有杀生物剂功效可得到显著增强，从而形成二氧化钛 - 黑色素混合纳米结构。然而，杀生物剂活性背后的机制和过程仍知之甚少。本文揭示了这些系统的基本作用机制，提供了关于它们与菌株特殊相互作用的机制信息。为此，将杀生物剂表征与电子顺磁共振（EPR）光谱相结合，以研究杂化物产生的自由基种类及其与革兰氏阴性菌外膜的相互作用。实验结果表明，二氧化钛介导的真黑素聚合导致混合纳米结构产生特殊的作用机制，其与细菌膜的强烈相互作用增强了真黑素自身降解产生的活性氧（ROS）的作用，这也与最终的杀生物剂作用协同。这些发现为开发对耐药菌株具有增强活性的基于真黑素的系统提供了战略信息。
