Microplastic pollution has become a critical global issue driven by our pervasive use of nondegradable microplastic materials in everyday life. These harmful plastics are found nearly everywhere on Earth, stemming from the degradation of tires, clothing, and plastic packaging.
Another key contributor to microplastics is the tiny plastic beads often included in cleansers, cosmetics, and various beauty products.
One promising solution to tackle this problem is to replace nondegradable plastics with degradable materials that have properties amendable for targeted applications.
In a groundbreaking effort, MIT researchers have created a new class of biodegradable materials that could replace the plastic beads now used in beauty products. These new polymers decompose into benign substances like sugars and amino acids.
Beyond their use in cosmetics, these biodegradable particles have the potential for additional applications. For instance, in a recent study, researchers demonstrated that these particles could effectively encapsulate nutrients like vitamin A. Fortifying foods with encapsulated vitamin A and other nutrients could assist the estimated 2 billion individuals globally who face nutritional deficiencies.
In 2019, Jaklenec and Robert Langer, an MIT Institute Professor and member of the Koch Institute, the senior authors of the paper, and their team introduced a polymer that encapsulated essential nutrients like vitamin A, showing that iron-fortified bread made with this polymer increased iron levels in consumers. However, the European Union classified this polymer, BMC, as a microplastic and enforced a ban in 2023.
In response, the Bill and Melinda Gates Foundation asked MIT researchers to develop a sustainable alternative. Led by Zhang, researchers turned to biodegradable poly(beta-amino esters), which break down into harmless sugars and amino acids. Modifying the material’s building blocks enhanced properties such as hydrophobicity and pH sensitivity. They created five candidate materials and identified one that efficiently dissolves in acidic environments like the stomach.
The team successfully encapsulated vitamins A, D, E, and C, as well as zinc and iron, which remained stable after boiling for two hours. After six months of high-temperature and high-humidity storage, over 50% of the nutrients remained intact.
To test their food fortification potential, the researchers added the particles to bouillon cubes, a staple in many African countries. They confirmed that the nutrients stayed intact after boiling for two hours. Jaklenec noted that bouillon presents a great opportunity to enhance nutrition for billions of people in sub-Saharan Africa. Safety tests on cultured human intestinal cells revealed no damage at doses relevant for food fortification, indicating the particles’ safety for consumption.
To explore the particles’ ability to replace traditional microbeads in cleansers, the researchers combined the particles with soap foam. They discovered that this mixture could remove permanent markers and waterproof eyeliner from the skin much more effectively than soap alone.
Additionally, soap mixed with the new microplastic proved to be more effective than a cleanser containing polyethylene microbeads. The researchers also discovered that these new biodegradable particles were better at absorbing potentially toxic elements, such as heavy metals.
“We wanted to use this as a first step to demonstrate how it’s possible to develop a new class of materials, to expand from existing material categories, and then to apply it to different applications,” said Linzixuan (Rhoda) Zhang, the papers’s lead author.
Thanks to a grant from Estée Lauder, the researchers are currently focused on further testing the microbeads as a cleanser and exploring additional uses, with plans to initiate a small human trial later this year. They are also in the process of collecting safety data that could support an application for GRAS (generally recognized as safe) status from the U.S. Food and Drug Administration, and they intend to conduct a clinical trial on foods enhanced with the particles.
The researchers aim for their findings to contribute to a significant decrease in the release of microplastics into the environment resulting from health and beauty products.
“This is just one small part of the broader microplastics issue, but as a society, we’re beginning to acknowledge the seriousness of the problem. This work offers a step forward in addressing it,” Jaklenec says. “Polymers are incredibly useful and essential in countless applications in our daily lives, but they come with downsides. This is an example of how we can reduce some of those negative aspects.”
Journal reference:
- Linzixuan Zhang, Ruiqing Xiao, Tianyi Jin, Xinyan Pan, Katharina A. Fransen, Shahad K. Alsaiari, Alicia Lau, Ruizhe He, Jooli Han, Benjamin J. Pedretti, Jing Ying Yeo, Xin Yang, Bradley D. Olsen, Alfredo Alexander-Katz, Zachary P. Smith, Robert Langer & Ana Jaklenec. Degradable poly(β-amino ester) microparticles for cleansing products and food fortification. Nature Chemical Engineering, 2024; DOI: 10.1038/s44286-024-00151-0
