RESUMEN
The synthesis and bottom-up assembly of nanocellulose by microbes offers unique advantages to tune and meet key design criteria-rapid renewability, low toxicity, scalability, performance, and degradability-for multi-functional, circular economy textiles. However, development of green processing methods that meet these criteria remains a major research challenge. Here, we harness microbial biofabrication of nanocellulose and draw inspiration from ancient textile techniques to engineer sustainable biotextiles with a circular life cycle. The unique molecular self-organization of microbial nanocellulose (MC) combined with bio-phosphorylation with a lecithin treatment yields a compostable material with superior mechanical and flame-retardant properties. Specifically, treatment of MC with a lecithin-phosphocholine emulsion makes sites available to modulate cellulose cross-linking through hydroxyl, phosphate and methylene groups, increasing the interaction between cellulose chains. The resultant bioleather exhibits enhanced tensile strength and high ductility. Bio-phosphorylation with lecithin also redirects the combustion pathway from levoglucosan production towards the formation of foaming char as an insulating oxygen barrier, for outstanding flame retardance. Controlled color modulation is demonstrated with natural dyes. Life cycle impact assessment reveals that MC bioleather has up to an order of magnitude lower carbon footprint than conventional textiles, and a thousandfold reduction in the carcinogenic impact of leather production. Eliminating the use of hazardous substances, these high performance materials disrupt linear production models and strategically eliminate its toxicity and negative climate impacts, with widespread application in fashion, interiors and construction. Importantly, the biotextile approach developed in this study demonstrates the potential of biofabrication coupled with green chemistry for a circular materials economy.
RESUMEN
Green manufacturing has emerged across industries, propelled by a growing awareness of the negative environmental and health impacts associated with traditional practices. In the biomaterials industry, electrospinning is a ubiquitous fabrication method for producing nano- to micro-scale fibrous meshes that resemble native tissues, but this process traditionally utilizes solvents that are environmentally hazardous and pose a significant barrier to industrial scale-up and clinical translation. Applying sustainability principles to biomaterial production, we have developed a 'green electrospinning' process by systematically testing biologically benign solvents (U.S. Food and Drug Administration Q3C Class 3), and have identified acetic acid as a green solvent that exhibits low ecological impact (global warming potential (GWP) = 1.40 CO2eq. kg/L) and supports a stable electrospinning jet under routine fabrication conditions. By tuning electrospinning parameters, such as needle-plate distance and flow rate, we updated the fabrication of widely utilized biomedical polymers (e.g. poly-α-hydroxyesters, collagen), polymer blends, polymer-ceramic composites, and growth factor delivery systems. Resulting 'green' fibers and composites are comparable to traditional meshes in terms of composition, chemistry, architecture, mechanical properties, and biocompatibility. Interestingly, material properties of green synthetic fibers are more biomimetic than those of traditionally electrospun fibers, doubling in ductility (91.86 ± 35.65 vs. 45 ± 15.07%,n= 10,p< 0.05) without compromising yield strength (1.32 ± 0.26 vs. 1.38 ± 0.32 MPa) or ultimate tensile strength (2.49 ± 0.55 vs. 2.36 ± 0.45 MPa). Most importantly, green electrospinning proves advantageous for biofabrication, rendering a greater protection of growth factors during fiber formation (72.30 ± 1.94 vs. 62.87 ± 2.49% alpha helical content,n= 3,p< 0.05) and recapitulating native ECM mechanics in the fabrication of biopolymer-based meshes (16.57 ± 3.92% ductility, 33.38 ± 30.26 MPa elastic modulus, 1.30 ± 0.19 MPa yield strength, and 2.13 ± 0.36 MPa ultimate tensile strength,n= 10). The eco-conscious approach demonstrated here represents a paradigm shift in biofabrication, and will accelerate the translation of scalable biomaterials and biomimetic scaffolds for tissue engineering and regenerative medicine.