CAREER: Structure-Function Analysis of PEG-Lipid Shedding for Rational Design of Targeted Nanoparticles

NON-TECHNICAL SUMMARY: Materials shape nearly every modern technology, from electronics to energy to biotechnology. One exciting class of materials used in biotechnology includes nanoparticles, which are extremely small building blocks that scientists can design to move through complex environments and perform specific tasks. By carefully changing their surfaces, nanoparticles can be programmed to recognize and deliver cargo to certain types of cells in the body, much like a mail carrier delivers packages to specific addresses. However, current materials designs do not reliably maintain this targeting ability, limiting what these technologies can achieve. A major reason for this challenge lies at the surface of the material itself. To make nanoparticles recognize specific cells, scientists stick targeting molecules to the surface using soft, flexible linkers. These linkers are essential to many nanoparticle designs, but they are not stable. When nanoparticles enter real-world environments such as the human body, these linkers can detach from the surface. As a result, the carefully engineered surface of the material changes, and the nanoparticle no longer functions as intended. Despite the widespread use of nanoparticles in biotechnology, scientists still do not understand what controls this process. This project seeks to answer a fundamental materials science question: How does molecular structure control the stability of soft, dynamic material surfaces? By building nanoparticles with precisely defined surface components and tracking how those components move and detach over time, this research will uncover clear rules that connect chemical structure to material behavior. These design rules will help scientists create nanoparticles with surfaces that remain stable and functional in complex environments, advancing the fields of biotechnology and materials engineering while supporting future technologies that rely on stable nanoscale materials. The project also includes an education program focused on inspiring and training the next generation of materials scientists and engineers. Through partnerships with Chicago-area community colleges, students will have the opportunity to participate in hands-on research, mentoring, and scientific programming. These activities are designed to build a strong workforce equipped to tackle future challenges in materials research. TECHNICAL SUMMARY: This research investigates the molecular mechanisms that govern the stability of nanomaterial surfaces, with a focus on polyethylene glycol-lipids, or PEG-lipids. Actively targeted nanoparticles often rely on PEG-lipids to anchor ligands such as antibody fragments, yet PEG-lipid desorption under physiological conditions leads to loss of surface functionality and diminished targeting performance. The central hypothesis is that PEG-lipid chemical structure dictates shedding behavior and downstream biological function. Polymeric nanoparticles provide a unique platform to test this hypothesis because PEG-lipids are not required for particle stability, enabling PEG-lipid shedding to be decoupled from nanoparticle disassembly and degradation. The research integrates custom nanomaterial synthesis with quantitative fluorescence imaging and in vitro assays across three thrusts. First, a library of fluorescent PEG-lipids with systematic variation in lipid tail number, tail length, saturation, and linkage chemistry is evaluated on polymersomes and micelles using FRET, FRAP, and TIRF microscopy to define structure-function relationships governing surface stability and shedding. Second, the influence of PEG-lipid structure on nanoparticle biodistribution and trafficking is quantified at cellular and subcellular scales using flow cytometry and confocal microscopy. Third, the functional consequences of PEG-lipid shedding are evaluated using T cell-targeted nanoparticles displaying antibody fragments attached either through PEG-lipids or by covalent linkage NSF Award ID: 2541599 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT,01003031DB NSF RESEARCH & RELATED ACTIVIT,01002930DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Lisa Volpatti | Institution: Northwestern University at Chicago, EVANSTON, IL | Award Amount: $439,364 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2541599 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2541599.html