Lignin is the most abundant aromatic compound found in nature. The rich functional groups of lignin are responsible for its antibacterial, antioxidant, anti-ultraviolet, and biocompatible properties. As modified lignin has a higher molecular weight, water solubility, and better surface activity, it is a good candidate for the construction of new biological materials. Lignin-based hydrogels are a type of functional materials with broad application prospects in the biomedical field. This review aimed to introduce the biological properties of lignin and the application of lignin-based hydrogels in the biological field.

Lignin, the second most abundant bio-renewable polymer in the world after cellulose, is widely used in industrial production. In recent years, nanoparticles have attracted increasing attention due to their excellent properties. Therefore, the preparation of lignin nanoparticles to obtain value-added products is an effective way to utilize their potential completely. This article describes the preparation methods of micro/nanosized lignin with different sizes and shapes, and provides a detailed introduction to their applications in biomedicine.