Growing Bacterial Cellulose-Based Sustainable Functional Bulk Nanocomposites by Biosynthesis: Recent Advances and Perspectives

In recent years, with the continuous development of nanomaterials and composite preparation methods, nanocomposites are playing an increasingly important role as structural materials or functional materials due to their outstanding properties. As an important part of nanocomposites, polymer-based nanocomposites have attracted the interest of researchers, whose preparation methods have been significantly expanded with the rapid development of polymer chemistry and physics. At present, nanomaterials can be combined with the polymer matrix to form various nanocomposite materials in multiple ways, ranging from simple blending to complex processes combining surface modification and in situ polymerization. However, these polymer-based nanocomposites are still limited by their incompatibility of structural strength and functionality and unsustainability of the preparation processes. As a new type of polymer-based materials, the polymers synthesized by microorganisms, especially bacterial cellulose (BC) produced by bacteria such as Gluconacetobacter xylinus, have great potential to overcome the above-mentioned problems. On the one hand, BC has a fine nanoscale three-dimensional (3D) network with extremely high strength. The continuous nanoscale 3D network means that the nanomaterials composited with BC can be interspersed in a 3D network, effectively exerting their functionality without compromising the strength of the composites. On the other hand, the process of microbial production of BC is completed under normal pressure and temperature without using toxic reagents and solvents, which gives it a huge advantage in terms of sustainability over traditional polymer synthesis. Unfortunately, the high-density 3D nanoscale network of BC is too tight to allow the entry of nanomaterials in a homogeneous way, which brings great difficulties to the composite process of BC and nanomaterials. Challenging this problem, a new in situ composite preparation strategy called aerosol-assisted biosynthesis (AABS) strategy has been proposed as a solution. This strategy cleverly combines the deposition of nanomaterial-contained aerosol and microbial synthesis of BC, leading to uniform dispersion of various nanomaterials in the BC network and the formation of nanocomposites. In this Account, we review the development history of composite preparation methods and discuss its trend from the perspective of matching of its critical factors in dimensions of space and time. From the view of the spatiotemporal overlap of the factors, we analyze how this AABS strategy combines the BC synthesis process and the composite formation in the dimensions of space and time, resulting in the universality, tunability, designability, scalability, sustainability, and other advantages of the AABS strategy. Furthermore, we look forward to the future where AABS-based composite preparation systems can be combined with artificial intelligence and automation systems to realize fully automatic and sustainable biointelligent fabrication.