Poster O20 - Utilizing a Sugar Beet Production Byproduct: Development of a Polymer-Based Coating for Biomaterial Applications

Introduction: Bacterial growth and thrombus formation are common complications associated with implanted medical devices. Over the years different coatings and materials have been created to limit the effects of these complications. A promising solution is using naturally derived materials to coat medical implants. These naturally derived materials can have inherent properties, like antimicrobial activity, that make them a viable option for biomaterial coatings. These natural materials can come from different sources including plant waste. Plant waste is commonly discarded making it a relatively cheap, abundant, and accessible material. The biopolymers extracted from plant waste are renewable and are derived from low-cost sources unlike animal derived polysaccharides such as heparin. Molasses desugarized solubles (MDS) is a byproduct produced in sugar beet plants. MDS is currently used in animal feed, dust control, de-icing roads, and fertilizer; however, recent research has shown that there are biopolymers in MDS (Abadam, 2021). These biopolymers could be used to create a biomaterial coating for medical devices. Biopolymers extracted from plants are a promising material because they can contain antimicrobial properties and they are relatively cheap. This study analyzes the chemical composition and chemical/biocompatibility properties of the biopolymers isolated from MDS to determine whether they could be used in a biomaterial coating.

Materials and

Methods: The biopolymers were isolated from MDS using dialysis. A 20% (v/v) solution of MDS in deionized (DI) water was dialyzed in 4.5 L of DI water over seven days. After dialysis, 25 mL aliquots of the solution were lyophilized for two days. The isolated biopolymers were then stored at room temperature. The chemical composition and size of the biopolymers were analyzed using nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), and gel permeation chromatography (GPC). The zeta potential of the biopolymers was also determined using phase analysis light scattering. The zeta potential was used to determine the surface charge of the biopolymers. This information will be used later on when a coating will be made with the biopolymers. After the chemical composition was analyzed, further tests were conducted to determine whether the biopolymers were antimicrobial and cytotoxic. The antimicrobial properties were analyzed using Kirby-Bauer tests and growth inhibition tests in solution. The microbes tested were Escherichia coli, Pseudomonas putida, and Saccharomyces cerevisiae. The cytotoxicity of the biopolymers was analyzed using the lactate dehydrogenase (LDH) and AlamarBlue assays. For both assays human adiposed derived stem cells (ADSC) were used. Lastly, the antioxidant activity of the biopolymers was measured using a DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay. The antioxidant activity was compared to ascorbic acid as a standard.

Results, Conclusions, and Discussions: The NMR, FTIR, and XPS results showed that the biopolymers contain aromatic rings, amine groups, hydroxyl groups, and carboxyl groups. These results were consistent with the expected compounds found in MDS. The GPC results showed that there were three main sizes of biopolymers that ranged from approximately 1800 g/mol to 84000 g/mol. The zeta potential of the biopolymers was -29.98 mV. This value indicates the biopolymers have a net negative surface charge. For creating the coating, 5 or 6 layers of PEMs will be deposited with the second to last layer having a positive surface charge so the terminal layer with the biopolymers will adhere. The Kirby-Bauer and growth inhibition tests in solution showed that the biopolymers contain antifungal activity. On average, the biopolymers inhibited S. cerevisiae growth by 30%. For cytotoxicity, the LDH assay showed that the biopolymers were not cytotoxic at a concentration below 100 μg/mL. For cell viability, the AlamarBlue assay showed that the cells were still viable in a biopolymer solution below 0.5 mg/mL over eight days. Lastly, the DPPH assay showed that the biopolymers have antioxidant activity, and they have a maximum radical scavenging activity of approximately 79%. Further research will be conducted to determine if the biopolymers contain any other antimicrobial properties against different gram-negative and gram-positive bacteria. Further research with cell viability will also be conducted. As previously mentioned, the future steps for this project are to develop a polyelectrolyte multilayers (PEMs) coating with the biopolymers. Once the coating is created, XPS, Kirby-Bauer, growth inhibition in solution, LDH, AlamarBlue, and DPPH tests will be repeated to determine whether the biopolymers retain the same properties in solution or different properties on a coating. The biopolymers will also be tested to determine whether they are anti-thrombogenic.

Acknowledgements (Optional): Reference: Abadam, Vidalina. “U.S. Sugar Production.” USDA ERS - Background, U.S. DEPARTMENT
OF AGRICULTURE, 19 Oct. 2021, www.ers.usda.gov/topics/crops/sugar-andsweeteners/background/