Grafting Vitamin B onto Lignin to Produce Highly Bioactive Materials for Wound Dressing Hydrogels

The low radical scavenging activity (RSA) and antibacterial efficiency of lignin limit its applications as a value-added bioactive material. In order to produce greener lignin-based bioactive agents, in this work, vitamin B1 (VB1) was grafted onto lignin nanoparticles (LNPs) through a simple Mannich reaction. The structure and bioactivities of LNP-VB were then studied, and the antimicrobial rates of LNP-30VB against Escherichia coli and Staphylococcus aureus reached 98 and 90%, respectively, increasing by 172 and 291% compared to that of LNPs. Meanwhile, the RSA of LNP-VB was measured by DPPH and HUVEC methods, and the RSA of LNP-30VB was enhanced from 71.9% (LNP) up to 82.4%. Therefore, the RSA and antibacterial activities of LNP-VB were simultaneously and greatly improved, and their mechanisms were also elucidated, which mainly depends on the structure evolution, such as more phenoxyl radicals and H⁺ can be dissociated from lignin phenol hydroxyl, and new forming tertiary amines will also affect the microbial physiological activity. Based on excellent bioactivities, LNP-VB was then utilized for the preparation of wound dressing hydrogels, and faster wound healing and less inflammation effects can be achieved. Meanwhile, the granulation tissue and re-epithelialization phenotype can also be observed at the edge of the wound when analyzed via H&E staining.