The Future of New Materials: A Synthetic Biology Perspective

The development of new materials marks the progress of human civilization. Different eras of human development, from the Stone, Bronze, and Iron Ages to the Steam, Electrical, and Information Ages, have all been defined by transformations in materials. A significant breakthrough in modern materials development was the invention and production of plastics. However, while pervasive plastic products have brought convenience to daily life, they have also imposed an immense burden on the ecological environment.

To mitigate ecological pressure, the development of low-carbon, eco-friendly, and sustainable alternatives has become the prevailing trend in contemporary materials science. Certain biomass materials found in nature (e.g., wood, silk, cotton) possess numerous superior characteristics, including high mechanical strength, programmability, multifunctionality, hierarchical structures, and dynamic features such as self-growth and self-repair. Consequently, products directly processed from these natural biological components currently hold a dominant position among sustainable materials. However, many functional biological components are available in limited quantities in nature (for instance, only 1 gram of adhesive byssal protein can be harvested from 10,000 California blue mussels). Furthermore, the purification processes for these materials are often costly and unsustainable. As a result, designing microbial heterologous fermentation using genetic engineering techniques is progressively becoming the predominant production method for such biological functional components.

Cells serve as natural factories for synthesizing biomolecules. Billions of years of natural selection and evolution have endowed cells with capabilities such as environmental responsiveness, specific molecule synthesis, and environmental adaptation. During cellular material production, environmental signals (e.g., small molecule compounds, mechanical forces, light) are captured by intracellular receptors. Following information processing by intracellular sensing pathways (including signal amplification, information storage, or signal transduction), these processes effectively link external information flow with intracellular metabolism and genetics.

Based on the outcomes of cellular signal processing, cells can accordingly express enzymes to synthesize, secrete, modify, or degrade specific biological components (such as proteins, polysaccharides, and lipids) (as illustrated below).

Synthetic biology is an engineering discipline that employs genetic manipulation tools to program and modify the behavior and function of living organisms, as well as to create novel life forms. The advancements in synthetic biology present new opportunities for the discovery, design, and production of novel materials. For instance, modifying living organisms through synthetic biology techniques can endow synthetic materials with customized functions and properties.

The involvement of living systems imbues "living materials" with intriguing properties, such as dynamic characteristics like environmental responsiveness, self-repair, and self-regeneration. Moreover, the programmability of living systems enables precise modulation of material properties through the design of complex genetic circuits. The exploration within materials synthetic biology can be broadly categorized into three areas:

(1) Designing and engineering chassis cells for the efficient heterologous expression of natural biological components;
(2) Rationally integrating diverse material modules through a "bottom-up" approach to design functionally tunable biomimetic materials;
(3) Leveraging genetic circuits to regulate the in situ synthesis of specific functional components within chassis cells, thereby developing "living" materials endowed with life-like characteristics.