Preparation of tailored lignin nanospheres with specific size and tunable structure by self-assembly of lignin from corn straw

As an environmentally friendly materials, lignin nanoparticles, especially the lignin nanospheres with controlled size or morphology, have shown great potentials in many areas. However, the lignin nanosphere with tailored structure was rarely reported to be prepared from lignin in raw lignocellulose. In this study, a protocol to produce lignin nanoparticles with tailored size and morphology directly from corn stover was investigated. Lignin was extracted from raw biomass with tetrahydrofuran (THF) as solvent, and then dialyzed in water. The fractionated lignin showed high hydrophobicity and dissolvability in organic solvent and was the ideal precursor to prepare nano-sphere, and the chemical modification of lignin was omitted. The smooth surface, non-porous structured and regular shaped spheres were formed through dialysis, which suggested that the dialysis time, dialysis temperature and the initial dosage of lignin were the factors effecting the morphology of lignin-nanosphere. By adjusting the factors, the morphology of lignin nano-spheres were able to be tailored with specific size and tunable structure, such as hollow nanosphere with 458-615 nm particle size, and solid nanosphere sized in 250-350 nm, 350-450 nm, 450-600 nm, 600-700 nm, 600-800 nm, 700-955 nm respectively. Moreover, the lignin nano-spheres with tailored structure showed different UV-blocking ability and bacterial culture capacity, which provided a promising development of lignin-based nanomaterials with raw biomass as the feedstock.