Review Articles

Due to the societal appeal in carbon emission reduction and neutralization, chemical recycling of waste polyester for valuable chemicals has attracted attention in an increasing number of applications. Research on chemical recycling of polyester wastes is currently rising sharply and becoming a hot spot gradually. Many technical and fundamental questions still need to be addressed, such as harsh depolymerization conditions (high temperature, long reaction time, low yields, etc.) and techno-economy and environmental sustainability matters. The chemical recycling protocol and optimization of degradable polyester wastes are systemically investigated along with short discussions on non-degradable ones. The thermoset polyurethane and epoxy adhesives derived from depolymerized waste polyesters for contributing to wood-based structural composite materials (e.g., laminated plywood, fire retarded wood coating, and transparent wood composites) along with life-cycle assessment and techno-economic analysis are also critically evaluated and analyzed. These novel insights are expect to open a new avenue to develop wood-based structural materials via value-added chemicals from polyester waste recycling, which contribute to the sustainable society along with prompting further research and extension in forestry biomaterials and renewable natural resources.

Graphical Abstract

Chitin is the second most abundant natural polysaccharide after cellulose and consists of N-acetyl-D-glucosamine units linked by β-1,4-glycosidic bonds. In nature, chitin does not accumulate due to the synergistic action of chitinolytic enzymes. Based on their catalytic domains, chitinases are classified into glycosyl hydrolase families GH18 and GH19. They are widely produced by bacteria and filamentous fungi. Different types of chitinolytic enzymes, including endochitinases, exo-acting enzymes, and N-acetylglucosaminidases, have been reported to exhibit antimicrobial and insecticidal activities, making them valuable tools for controlling phytopathogenic fungi and insect pests. Chitin degradation generates chitooligosaccharides (COS), which possess diverse biological properties such as antimicrobial, antioxidant, anti-inflammatory, and antitumor activities, contributing to improved human health. Microbial chitinases are also applied in several industrial and environmental processes, including protoplast formation, single-cell protein production, and dye removal. Advances in recombinant expression and genetic engineering have enhanced chitinase production, stability, and catalytic efficiency. Moreover, recombinant chitinases have been successfully utilized in biocontrol strategies and in developing transgenic plants with increased resistance to phytopathogens. This review highlights the broad agricultural, industrial, and biomedical applications of chitinases and their crucial role in promoting environmental sustainability and advancing bio-based industrial processes.

Biofilm-associated infections are a major medical problem that is responsible for nearly 80% of human microbial infections. These bacterial communities are protected by a strong extracellular matrix that limits antibiotic penetration and supports persister cells and quorum-sensing–driven resistance. Biofilm development occurs in several stages and ultimately forms complex structures that block antimicrobial action. To overcome this, chemical strategies include quorum-sensing inhibitors, matrix-degrading agents, antimicrobial peptides, and photodynamic therapy. Biological approaches use bacteriophages, enzymes such as DNase, and probiotics that disrupt biofilms through competitive mechanisms. Combination therapies—such as antibiotic-phage or enzyme-antibiotic treatments—show improved effectiveness. Advanced delivery systems involving nanoparticles, liposomes, and hydrogels enhance drug penetration in biofilms, particularly in wound care. New technologies, including AI-guided drug discovery and CRISPR targeting, are advancing future anti-biofilm treatments.

Biomass densification and molding technology can compress and densify crushed materials into portable solid fuels with a certain shape and density. Such densification has the advantages of high combustion efficiency, high calorific value, environmental protection, and cleanliness. In recent years, scholars have used the finite element method and discrete element method to simulate biomass densification and molding technology, revealing the flow and deformation laws of materials in the biomass densification and molding process from different perspectives. This work has provided reference and guidance for the optimization of biomass densification and molding mechanism and molding dies. This article first reviews the basic ideas of finite element method, as well as the application of ANSYS and ABAQUS in biomass densification and molding technology. Secondly, it reviews the basic ideas of discrete element method and the application of EDEM and PFC in biomass densification and molding technology. Finally, it reviews the application of combined finite element method with discrete element method in biomass densification and molding technology. The content of the article has certain reference and guidance significance for the numerical simulation of future biomass densification and molding technology.