Location: Sustainable Biofuels and Co-products Research
Project Number: 8072-41000-110-004-I
Project Type: Interagency Reimbursable Agreement
Start Date: Sep 1, 2021
End Date: Aug 31, 2025
Objective:
Throughout history, human beings have been threatened by various plagues, epidemics and other contagious diseases. In fact, even now the current COVID-19 situation is causing a worldwide pandemic. For bacteria and viruses, direct contact is a major route for the spread of infectious diseases. These infectious agents can be effectively dispersed simply through touch. While there are many products that kill bacteria, most need to be constantly reapplied to surfaces and many have a caustic nature. The proposed project focuses on engineering advanced antimicrobial bio-polymers with excellent stability and reusability properties from plant-based non-edible oil and agricultural-based waste oil feedstocks, which is designed to respond to the NIFA Program Area Bioprocessing and Bioengineering (Priority Code A1531) with focus on these two specific priorities: 1. Engineer new or improved products and processes that make use of materials from agricultural origin (including, but are not limited to, bioplastics and bio-composites. 2. Advance or expand utilization of waste and byproducts generated in agricultural and food systems.
Objectives and Specific Tasks:
Objective 1. Development of two novel thermosetting antimicrobial bio-polymers, bio-epoxies and bio-polyurethanes.
• Task 1. For the epoxy bio-polymer development, this task has considered three sub-tasks: improve the economics, improve the functionality, and engineer epoxy bio-polymers.
• Task 2. For the bio-polyurethane development, this task has considered two sub-tasks: design new ionic polyols (Part B) and formulate these polyols (Part B) to antimicrobial polyurethane coatings.
Objective 2. Evaluation of the thermosetting bio-polymers antimicrobial properties.
• Task 1. Study antimicrobial properties.
• Task 2. Study bio-polymer leaching and reusability.
Objective 3. Study of the structure-property relationship of antimicrobial bio-polymer coatings.
• Task 1. Balance the relationship between antimicrobial activity and performance.
• Task 2. Evaluate the mechanical properties for coatings applications.
Objective 4. Investigation of the biodegradability and cytotoxicity of the bio-polymer coatings.
• Task 1. Study biodegradability properties.
• Task 2. Study cytotoxicity, this task has considered two sub-tasks: design multi-assay approaches to predict key receptor affinities and toxicity assessments using multi-factor screening tools.
Approach:
Objective 1 focuses on the development of new economically viable and environmentally friendly antimicrobial thermosetting bio-polymers derived from non-edible oils. Thermosetting polymers such as epoxy resins and polyurethanes are widely used in coatings, paints, floorings and adhesives. They often have favorable mechanical properties with high thermal and chemical resistance. However, many of the reported antimicrobial polymers have been prepared from costly starting materials, and some are cytotoxic or water soluble and therefore not suitable for antimicrobial coatings. The tasks proposed in this objective will tackle these issues.
A variety of non-edible bio-oils including waste oils will be used to build upon and optimize the ARS patented arylation zeolite catalytic branching process to make a family of cost effective phenolic-branched chain fatty acid (PBC-FA) monomers. These monomers will be used in the development of the two antimicrobial thermosetting bio-polymers (bio-epoxies and bio-polyurethanes). For the bio-epoxy materials, the monomers will be converted to a PBC-FA-amide amine curing agent through an amidation process followed by curing of the epoxy resins to generate the bio-epoxies. As for the bio-polyurethane products, the PBC-FA monomers will be converted to polyols which will then be formulated with a variety of commercially available isocyanates to create the desired bio-polyurethanes.
Objective 2 focuses on evaluating the antimicrobial properties of the designed bio-polymers against both Gram-positive and Gram-negative bacteria. It is well-known that when a bacterium approaches a cationic solid substrate (e.g., bio-polymer), the positive charges on the substrate can replace the cations in the cell membrane. This in turn can lead to a release of the mobile cations, which destabilize the cell’s outer membrane, increase permeability, and cause cell death. Since our bio-polymers are designed to have sufficient cations on their surfaces to kill bacteria, performing the antimicrobial tests will demonstrate that our bio-polymers contain these important functionalities.
Objective 3 focuses on the structure-property relationship between the antimicrobial activity and performance of the bio-polymers. Understanding this relationship will help improve the value of our bio-polymers in both coating and surface applications. These tests will be performed by formulating these three aspects of the PBC-FA monomers: cation numbers, molecular weights and hydrophilicity. The results will reveal the water-resistance and mechanical performance of our bio-polymers and correlate those valuable properties to the bioactive behavior of the various structural variants. The mechanical properties of the bio-polymers will then be tested to obtain the materials’ tensile strength, modulus and elongation breaking points, which will indicate the durable and reliable property of the products.
Objective 4 focuses on the biodegradability and cytotoxicity studies of the most promising bio-polymers. Standard test methods and protocols will be applied to the bio-polymers to establish and quantify the biodegradability and cytotoxicity of the new coatings.
