## 1 Introduction  
In recent years, biomass materials have garnered increasing amounts of attention due to their excellent biocompatibility, high biodegradability, easy modification, low cost, and high sustainability [1, 2]. With the development of nanotechnology and biotechnology, these naturally abundant and easily regenerated materials, which include cellulose, hemicellulose, polysaccharides, proteins, peptides, and other kinds of biopolymers, have exhibited many advantages for a diverse range of applications [3, 4, 5].  
In modern biomass utilization, biomass materials have come to be considered good candidates for solving problems related to the use of renewable and sustainable energy sources [6, 7]. Biomass gasification can effectively convert solid fuels into gases, thereby representing a method for reducing the consumption of global fossil fuels [8]. In addition, biomass can be used as a high-quality carbon source to produce carbon-based nanomaterials, such as graphene, carbon nanotubes, carbon nanofibers, and carbon dots, which can be further utilized for energy storage and electrochemical catalytic applications [9, 10, 11] due to the highly specific surface area in biomass material, as well as its abundant active sites and adjustable dimensions from 0D to 3D. Biomass materials can also be processed to create various functional bionanomaterials. Due to their unique biomimetic properties, biomass exhibits high potential for the biomimetic synthesis of various metal and metal oxide nanomaterials [12, 13]. Moreover, biomineralization based on biomass materials promotes the application of formed bionanomaterials in bone and dental tissue engineering [14, 15].  
In addition, it is easy to carry out the structural design and functional regulation of biomass materials for advanced applications. With the help of self-assembly, electrospinning, vacuum filtering, freeze drying, 3D printing, and other techniques, biomass materials can be constructed into structure-tailorable materials from nanofibers to nanofilms, membranes, hydrogels, and aerogels [16, 17, 18, 19], in which the porous frameworks constructed provide the space for these materials to be incorporated within other nanomaterials, such as polymers, nanoparticles, quantum dots, nanotubes, and 2D materials, making it possible to achieve functional regulation of biomass materials. It has been reported that the incorporation of biomass materials with natural rubbers or other polymers reinforced the structure and properties of polymer materials [20, 21], demonstrating promising application in chemical engineering and industrial fields. Through structural and functional modulation, the biomass-hybrid materials presented improved biological, chemical, and physical properties, facilitating their application in energy storage, adsorption and filtration, antimicrobial surfaces, biomedical engineering, sensors/biosensors, and wearable devices [22, 23].  
The aim of this Special Issue, therefore, was to compile contributions that focus on (but are not limited to) biomass use in materials science and nanotechnology in order to present recent advances in the synthesis, functionalization, hybridization, and application of biomass materials.