Bacterial cellulose (BC) is a crucial polysaccharide synthesized by some bacterial species such as Agrobacterium, Aerobacter, Achromobacter, Sarcina, Acetobacter, Rhizobium, Salmonella, and Azotobacter. Particularly, Gluconacetobacter xylinus (previously recognized as Acetobacter xylinus and then named Komagataeibacter xylinus) can produce a higher quantity of BC than other species. BC presents several remarkable features such as microporosity, high water holding capacity, good mechanical properties, and good biocompatibility. Since its discovery, BC has been used for wound dressing, drug delivery, artificial blood vessels, bone tissue engineering. Nevertheless, the wide range of applications of BC is restricted due to several issues such as the absence of antimicrobial properties, antioxidant, and conducting properties, etc. These restrictions necessitate the introduction of other functionalities into BC to widen its applications in the biomedical field. Molecular biology is applied to increase the production of BC and to regulate the performance of BC, including the successful establishment of a lambda Red and FLP/FRT-mediated site-specific recombination system in K. xylinus, and the use of the CRISPR interference (CRISPRi) system in K. xylinus to control the expression levels of galU. Additionally, BC can be simply manipulated to form its derivatives or composites with enhanced physicochemical and functional properties. Several polymers, carbon-based nanomaterials, and metal nanoparticles (NPs) have been introduced into BC by ex-situ and in-situ methods to design hybrid materials with enhanced functional properties. The results show that the composite materials showed antibacterial activities against tested Gram-positive and Gram-negative bacterial strains. In addition, a wound dressing based on BC containing ε-polylysine (ε-PL), cross-linked by a biocompatible and mussel-inspired polydopamine (PDA) for promoting infectious wound healing was designed. The resulted membranes showed strong antibacterial properties against tested bacteria by both in vitro and in vivo evaluations. The membranes also exhibited hemocompatibility and cytocompatibility by in vitro investigations. Moreover, the functionalized membranes promoted infected wound healing using Sprague–Dawley rats as a model animal. A complete wound healing was observed in the group treated with functionalized membranes, while wounds were still open for control and pure BC groups in the same duration. Histological investigations indicated that the thickness of newborn skin was greater and smoother in the groups treated with modified membranes compared to neat BC or control groups. These results revealed that the functionalized membranes have great potential as a dressing material for infected wounds in future clinical applications.
 

Bacterial cellulose; Synthesis; Structural features; Modification strategies; Biomedical applications