It’s not often that chemists find a quick, simple and cheap method for making things using widely available ingredients, but researchers have done just that: They’ve created elegant little capsules and coatings in water simply by mixing iron and a compound from plants called tannic acid. The soft coatings form on their own around whatever else is in the water — glass beads, bacteria, gold nanoparticles and more. Just changing the solution’s pH can prompts the coatings to disassemble.
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The coatings’ ingredients are considered safe — tannic acid is found in wine, while iron is an important element for living things. That means the capsules might help in delivering drugs in the body or find use in cosmetics or foods, says bioengineer Gregory Payne of the University of Maryland in College Park.