A researcher group led by Prof. ZHU Jin at the Ningbo Institute of Materials Technology and Engineering of the Chinese Academy of Sciences, in cooperation with Prof. CHEN Jing at NIMTE and researchers at Tsinghua University, has proposed a facile method to prepare antibacterial lignin-based polyurethane/silver (Ag) composite foam which facilitates wound healing as wound dressings.

Results of the study have been published in Biomacromolecules.  

Antibacterial wound dressing is a critical to excessive exudate absorption and wound infection prevention, thus promoting tissue repair. As an effective strategy to prepare high-performance antibacterial wound dressings, the incorporation of polyurethane materials within wound dressings has drawn great attention internationally. However, the dependence on petroleum resources, lack of antibacterial activity, and complex preparation process of traditional polyurethane foams have restricted their efficacy in biomedical applications. 

By virtue of a simple one-step foaming and in situ reduction method, the researchers prepared lignin-based polyurethane foam as new biomass wound dressings, with a small amount of silver nanoparticles (i.e., Ag NPs) loaded on the skeleton of the composite foam. 

During the preparation of polyurethane, the natural compound lignin with metal-reducing ability was applied as a reducing agent to reduce silver ions to Ag NPs in situ.  

With an open porous structure, the developed antibacterial lignin-based polyurethane/Ag composite foam showed enhanced thermal, mechanical and antibacterial properties, as it almost completely (99%) inhibited the growth of Escherichia coli within one hour and Staphylococcus aureus within four hours, respectively.  

In addition, evaluations in an animal model of mice indicated the prepared foam dressing effectively promoted new tissue generation and collagen deposition in full-thickness skin wounds, thereby facilitating wound healing. 

This study provides insights into the development of biological antibacterial polyurethane dressings. The developed high-performance antibacterial lignin-based composite foam shows great potential for mass production and clinical application.  

This work was financially supported by the National Key Research and Development Program of China, the OCE Project #29983 (Canada), the National Natural Science Foundation of China, etc. 

The synthesis and application of lignin-based polyurethane/Ag composite foams. (Image by NIMTE)