Decoding the mechanism of toxicity of soft lignin nanoparticles to bacteria cells: an interplay between the nanoparticle properties and the characteristics of the cell surface

Lignin is a natural substance found in plants and wood. Recently, researchers have explored ways to change lignin into very small particles known as lignin nanoparticles. These nanoparticles have promising applications. They can be used to create food packaging that fights bacteria. They can also be used as wound dressings that help prevent infections. These particles can also be placed in materials that clean water by trapping microbes. However, how these nanoparticles enter and affect bacterial cells is not well understood. This project will investigate how changing the particle properties (size, charge and others) affect their ability to kill bacteria in water. The research team will explore the effectiveness of these lignin nanoparticles in fighting different types of bacteria. The team will identify how the design of the lignin nanoparticles and the specific types of bacteria they target can influence their antibacterial strength. By understanding what helps lignin nanoparticles bind to and impact bacteria, the team will improve the performance of the particles. The team will use microscopes to examine the tiny pores of bacteria cells to understand how size affects the ability of the lignin nanoparticles to move through pores and enter the bacteria. The team will also explore how the stickiness of both bacteria and the lignin nanoparticles impact particle-bacteria connections. Lastly, the team will investigate how the electric charges of bacterial cells and lignin nanoparticles change the ability of these nanoparticles to kill bacteria. The project also includes educational programs aimed at helping students understand the importance of using natural plant-based materials in daily use. The team will create a minicourse and offer hands-on laboratory experience for both college and high school students. Students will learn both the basic concepts of lignin nanoparticles and participate in practical experiments stemming from this research. The educational activities will encourage students to think critically about how natural materials, microbiology, and engineering all play a role in the overall quality of human life. The team is committed to inspiring students to see how using more natural materials can improve well-being and support the national economy. Advancing the development of lignin nanoparticles with tailored antimicrobial properties will require a comprehensive understanding of the interplay between cell surface characteristics and the chemical and morphological features of lignin nanoparticles. The overarching objective of this project is to elucidate the critical factors determining the toxicity of lignin nanoparticles to microorganisms. The research will assess how cell characteristics, including hydrophobicity, surface charge, and cell envelope topography, influence particle-cell interactions. Concurrently, the research team will evaluate the extent to which the size, hydrophobicity, and surface charge of the lignin nanoparticles modulate their antimicrobial properties. This dual approach will provide mechanistic insights into the toxicity of lignin nanoparticles and enable the rational design of nanoparticles with targeted antimicrobial activity, addressing a significant knowledge gap in lignin-based nanomaterials research. The project team will: (1) utilize advanced imaging techniques to characterize the presence and dimensions of pores in the cell walls of Gram-positive and Gram-negative bacteria, and determine how lignin nanoparticles of varying sizes traverse these structures to access the intracellular environment, thereby clarifying the role of cell topology and the size of the lignin nanoparticles in toxicity mechanisms; (2) investigate the influence of hydrophobicity in both bacterial cells and lignin nanoparticles on the toxicity, studying the intensity of cell-particle adhesion through hydrophobic interactions; (3) examine the impact of cell surface and particle charges on the antimicrobial a NSF Award ID: 2553277 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Andreia Fonseca de Faria | Institution: University of Florida, GAINESVILLE, FL | Award Amount: $401,267 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2553277 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2553277.html