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Author ORCID Identifier
https://orcid.org/0000-0001-8742-3249
AccessType
Open Access Dissertation
Document Type
dissertation
Degree Name
Doctor of Philosophy (PhD)
Degree Program
Chemical Engineering
Year Degree Awarded
2024
Month Degree Awarded
February
First Advisor
Jessica D. Schiffman
Second Advisor
Lauren B. Andrews
Third Advisor
Jungwoo Lee
Fourth Advisor
D. Julian McClements
Subject Categories
Chemical Engineering
Abstract
Bacteria play a pivotal role in daily life from digesting nutrients to degrading pollutants in the environment. To exploit the benefits that living bacteria have to offer, encapsulation systems are needed that keep bacteria alive and deliver them to specific environments. Nanofibers composed of the biopolymer alginate would be beneficial for the encapsulation and on-demand release of probiotic bacteria due to the high surface area to volume ratio of the nanofibers and the pH-dependent behavior of alginate. Additionally, flexible and porous nanofiber mats are compatible with a variety of biomedical technologies. In my dissertation, I have developed probiotic-loaded, alginate-based nanofiber mats and demonstrated their use in two biomedical applications. Electrospinning of alginate into polymer nanofibers is challenging due to the high viscosity, surface tension, and conductivity of the charged polymer in aqueous solutions; these challenges were overcome using a biocompatible carrier polymer, polyethylene oxide, and an FDA-approved surfactant, polysorbate 80. The nanofibers were crosslinked using calcium ions to create water-stable, biocompatible nanofibers. While previous literature has demonstrated the use of ethanol-based crosslinking systems, aqueous and glycerol-based calcium chloride crosslinking systems were established in this work to create chemically resilient, alginate nanofibers for bacterial encapsulation. A probiotic, Lactococcus lactis, was encapsulated within the alginate-based nanofibers using a coaxial electrospinning setup to achieve a high bacteria loading (>109 colony forming units/g of electrospun mat). Encapsulated bacteria remained viable after crosslinking in the aqueous and glycerol-based systems whereas they were completely deactivated by the ethanol-based system. The encapsulated bacteria in these crosslinked alginate fibers were able to inhibit the growth of pathogenic Staphylococcus aureus, which is ideal for wound dressing applications. For the delivery of probiotics into the gut, antacid was formulated into the fibers to reduce acidic insult toward the encapsulated probiotics in a simulated stomach phase. The nanofibers also showed targeted release of viable bacteria past the stomach into the intestines. Overall, this dissertation provides important insights into the electrospinning of gut probiotics within alginate nanofibers for biomedical applications, while also laying the groundwork for other biomedical and environmental applications where delivery of beneficial living bacteria is needed.
DOI
https://doi.org/10.7275/36199022
Recommended Citation
Diep, Emily, "Electrospinning living bacteria into alginate-based nanofibers for biomedical applications" (2024). Doctoral Dissertations. 3043.
https://doi.org/10.7275/36199022
https://scholarworks.umass.edu/dissertations_2/3043
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.