The textile industry’s linear model of production and reliance upon nonrenewable resources to manufacture synthetic fibers, dyes, and finishing agents make it one of the most polluting industries globally, responsible for 1.2 billion tons of CO₂ emissions per year, 20% of wastewater, and 35% of marine microplastic pollution. Similarly, medical textiles fabricated as wound dressing or replacement grafts utilize petroleum-derived polymers processed with harsh solvents, not only limiting their biocompatibility and scalability, but also creating environmental concern at industrial volumes.
To mitigate these negative environmental and health impacts, new biofabrication strategies are required to design functional biomaterials that not only meet performance criteria for medical or non-medical application, but also support a sustainable circular economy. Inspired by the complex bottom-up assembly and regenerative potential of nature, the objective of this thesis is to harness biofabrication and in particular, microbial biosynthesis of nanofibril cellulose for the development of non-medical and medical textiles. Specifically, this thesis aims to improve our understanding of the microbial cellulose fabrication process and establish a controlled microbial cellulose modular engineering platform. By controlling biosynthesis and applying sustainability considerations to polymer processing strategies, we can regulate bacterial response and control resultant material properties for the engineered nanocellulose, targeting performance goals relevant for the textile industry. For medical applications, a controlled purification strategy will be explored for the development of a functional and biocompatible matrix.
To this end, both biofabrication and post-processing strategies were assessed for the synthesis of microbial cellulose biotextiles that meet low toxicity and environmental impact criteria. The biofabrication of microbial cellulose with Gluconacetobacter xylinus was first evaluated by determining the effects of carbon source and concentration on bacterial response and emergent biomaterial properties. While glucose, fructose, sucrose, mannitol, and xylitol all supported microbial growth, differences observed in cellulose production rate, and mechanical properties revealed unique opportunities to regulate material properties through biosynthesis.
Post-synthesis processing offers another level of control in achieving desired material properties. Both green chemistry and bioinspired processes were developed using plant-derived lecithin, green plasticizers (sorbitol and glycerol), and tannin-iron complexation to control elastic and viscoelastic properties of the microbial cellulose. It was demonstrated that these methods altered chemical crosslinking and stabilized mechanical properties, in which lecithin and tannin-iron complex imbued biomaterials with flame retardant and anti-bacterial properties, respectively. Life cycle analyses were performed to ensure transparency in considerations of climate and health impact of carbon source for biofabrication, crosslinkers and plasticizers for scaled up functionality.
After developing and optimizing the purification protocol, the biocompatibility of microbial cellulose scaffolds was evaluated through in vitro culture with human monocyte-like cells (THP-1) and also with human ligament fibroblasts. It was observed that microbial cellulose did not stimulate a pro-inflammatory response from naïve macrophages, and the matrix supported fibroblast viability and growth over two weeks of culture. In comparison to biocompatible synthetic PLGA:PCL unaligned microfiber scaffolds, microbial cellulose stimulated comparable macrophage cytokine secretion, albeit the matrix maintained lower cell attachment.
Collectively, this thesis has elucidated critical synthesis and biofabrication criteria that dictate the performance properties of microbial cellulose for: 1) regenerative, multi-functional biotextiles; and 2) biocompatible scaffold supporting in-vitro eukaryotic cell viability and basal-inflammatory response. These approaches are innovative as this work represents the first attempt to systematically understand how to leverage biofabrication to engineer multifunctional microbial cellulose with tailorable nano-, micro-, and macro- scale properties. Beyond biotextile development, this material platform and optimized green processing strategies demonstrate the potential of engineering regenerative materials for a circular material economy across various industries.
| Identifer | oai:union.ndltd.org:columbia.edu/oai:academiccommons.columbia.edu:10.7916/bgdr-aj41 |
| Date | January 2023 |
| Creators | Antrobus, Romare |
| Source Sets | Columbia University |
| Language | English |
| Detected Language | English |
| Type | Theses |
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