Experimental and Theoretical Study of Madder-Associated Dyestuffs on Silk: Adsorption of Kinetics, Thermodynamics and Molecular Docking

ABSTRACT

In this work, dyed samples were self-prepared from two methods including madder dyeing and mordant dyeing by madder combined with Al³⁺ at different temperatures, and their kinetics and isothermal adsorption were both discussed. Weber–Morris diffusion model and Freundlich model were found to be more suitable in dyeing for kinetics and thermodynamics. Through SEM, FTIR and fastness tests, the dyeing performances were displayed and the possible structure between madder dyes and the complex with Al³⁺ were illustrated. By molecular docking, madder dyes showed combination with glutamic acid predominantly. After introducing metal ion, the shortage of hydrogen bonds length was observed. It was initially employed to elucidate the potential binding modes between dyes and proteinaceous fibers. Overall, through experimental dyeing and curve fitting, this study provided insights into the dyeing mechanism of madder-associated dyestuffs on silk. Moreover, molecular docking elucidated the dyeing mechanism further, highlighting that the presence of metal ion enhances the firmness of the staining. The elucidation of dyeing mechanism not only provided valuable theoretical support for color restoration but also shed light on the practically modify of methods in obtaining ideal color. These results could serve as inspiration for conservators to maintain the vibrancy and longevity of dyed silks.

摘要

本工作采用茜草染色和茜草与Al³⁺在不同温度下进行媒染剂染色两种方法制备了染色样品，并对其动力学和等温吸附进行了讨论. Weber-Morris扩散模型和Freundlich模型在动力学和热力学方面更适合染色. 通过SEM、FTIR和牢度测试，展示了茜草染料的染色性能，并说明了茜草与Al³⁺配合物之间可能的结构. 通过分子对接，茜草染料主要与谷氨酸结合. 引入金属离子后，观察到氢键长度不足. 它最初用于阐明染料和蛋白质纤维之间的潜在结合模式. 总之，通过实验染色和曲线拟合，本研究深入了解了茜草类染料在丝绸上的染色机理. 此外，分子对接进一步阐明了染色机制，强调了金属离子的存在增强了染色的牢固性. 对染色机理的阐明，不仅为色彩恢复提供了宝贵的理论支持，而且也为实际改进获得理想色彩的方法提供了参考. 这些结果可以为保护人员保持染色丝绸的活力和寿命提供启发.

KEYWORDS:

• Madder-associated dyes
• madder dyeing
• mordant dyeing
• kinetics
• thermodynamics
• molecular docking

关键词:

• 马德尔缔合染料
• 马德尔染色
• 丝光染色
• 动力学
• 热力学
• 分子对接

Acknowledgments

The authors thanked the Research Centre of Analysis and Test of East China University of Science and Technology for help on data and characterization.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Y.J. Guo and W.Q. Zhang conceived the conceptualization. W.Q. Zhang provided all the resources. Y.J. Guo conducted the dyes extraction, dyeing process and color differences measuring and characterize of SEM. Y.J. Guo conducted the molecular docking dependently. Y.J. Guo and X.D. Zhou interpreted the data. Y.J. Guo and X.D. Zhou drew all figures. Y.J. Guo wrote the original draft. M.Q. Wu, L.F. Zhang, X.Y. Luo as well as W.Q. Zhang co-wrote the paper in review and editing. All authors had given approval to the final version of the manuscript.

Additional information

Funding

This work was supported by the Ministry of Science and Technology of the People’s Republic of China under [Grant number: 2020YFC1522501].