On the sun-soaked beaches of Miami, sunscreen is a daily ritual. Just a few miles away at the University of Miami, chemical, environmental, and materials engineering Ph.D. student Casey Posner is researching how to make that protection safer and more sustainable.
Working under the mentorship of Samiul Amin, professor of practice at the College of Engineering, Posner is developing sunscreen formulations in the Soft Matter Product Design Lab that blend eco-friendly innovation with rigorous medical standards. She believes sunscreen is a public health tool and wants to rethink how new formulations can protect people and the planet.
"I really love chemistry and figuring out how things work," she said. "That's why I want to put out a more accurate narrative of how these products work and protect people. It's a public health issue."
At the center of her formulations are biosurfactants, biofermented ingredients that can replace synthetic emulsifiers. These materials are biodegradable, often derived from food waste, and ethically sourced, making them especially appealing at a time when consumers are demanding more sustainable products. Creating them, however, is expensive, which has kept many companies from fully embracing the technology. Still, Posner wants to prove their worth.
"I'm part of the generation where sustainability is important," she said. "But natural isn't always better. For example, snake venom is natural, but it's a poison. We need to find the right ingredients and formulations that work well for both the human body and the environment."
Posner's dual focus is what sets her research apart. Partnering with Delia Shelton of the Department of Biology, she is using zebrafish to test ecotoxicity because their genome is highly similar to humans. This allows her to assess safety while also evaluating how sunscreen behaves in water systems, where its ingredients have come under fire for their role in ocean acidification. She also is collaborating with researchers at the Miller School of Medicine to test skin health and SPF effectiveness under Food and Drug Administration guidelines.
Unlike most studies that focus only on specific ingredients, Posner is examining finished products to better understand ingredient interactions and how the different components work together. Her goal is to enhance efficacy through deep mechanistic understanding and formulation process engineering to create a framework, which she calls a "toolbox," that manufacturers and brands can use to design the next generation of sunscreens.
There is already significant interest in her work. Later this month, she will present her findings at the Sunscreen Symposium hosted by the Society of Cosmetic Chemists, where industry leaders will gather to discuss the future of sun care. Her research also extends beyond sunscreen. The same bio-based techniques could transform industries including food, paints and coatings, and agricultural pesticides.
For Posner, though, the heart of the research remains the same.
"These are products being designed to help and protect people," she said. "I want to make something that can improve someone's life."
