Waste from nut used in herbal teas can be made into hydrogel with many medical uses, UChicago scientists find

CBS News

21-03-2025

A gelatinous substance that would otherwise be waste from a nut often used to make herbal tea can be made into a hydrogel with all different biomedical uses,
University of Chicago researchers recently discovered.
In research published last month, UChicago scientists created a hydrogel out of husks from the malva nut. In traditional Chinese medicine, the malva nut, or
Pang Da Hai
(胖大海) belongs to the "cool herbs that transform phlegm and stop cough" category of medicinal flora,
according to Me & Qi.
The tea made from malva nuts is used as a remedy for a sore throat, much like ginger or lemon tea might be, UChicago researchers said. A small dried nut is placed in hot water, and a tea with a sweet and smooth quality results.
But the U of C researchers were not looking at the nuts themselves, but the gelatinous substance husks — which swell into a gelatinous substance that would typically be thrown away after making the tea.
"Originally, it's an oval shape one centimeter in width. Once you soak it in the water, it will expand about eight times in volume and 20 times by weight, turning into a gelatinous mass, like a jelly," Changxu Sun, a Ph.D. student at the University of Chicago Pritzker School of Engineering, said in a news release. "After you drink the beverage, you're left the jelly as a waste. People usually throw that out."
But Sun and UChicago Chemistry Professor Bozhi Tian realized the substance was a natural hydrogel — a viscous, water-based substance that has a variety of health care uses.
The U of C noted that hydrogels are used in wound care — and are more effective at fighting infection and promoting healing beyond a mere bandage. They are also used in drug delivery systems, pacemakers and other implanted bioelectronics, tissue repair, and ECG and EKG readings, the university said.
However, turning malva nuts into a natural hydrogel didn't just involve making some tea and then scooping out the gel that would otherwise have been tossed.
Researchers put the malva nuts in a blender and pulverized them first, then ran them through a centrifuge to separate out the soft hydrocolloid substance from the organic polymers, or lingins, from which their shells are made, the U of C said.
The researchers freeze-dried the hydrocolloid solution, resulting in a dehydrated "pure malva nut polysaccharide," the U of C said.
If that polysaccharide is rehydrated — UChicago compared the process to a dry sponge regaining its shape under a faucet — a hydrogel results.
Having produced the malva nut hydrogel, the UChicago researchers began to test it out for uses such as wound care and biomonitoring, the university said.
"We found it demonstrated superior performance and qualities compared to commercial ECG patches," Sun said in the release, "and then we also applied to the tissue surface in vivo, demonstrating great recording of biosignals."
Sun told the university he hopes the newly discovered hydrogel could be a useful and cheaper option for medical applications around the world — particularly low-income countries in Southeast Asia where the malva tree grows, the U of C said.
The research was published
"Sustainable Conversion of Husk into Viscoelastic Hydrogels for Value-Added Biomedical Applications,"
was published back on Feb. 17 in the journal Matter.