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An artist's impression of light-sensitive cells encapsulated in an implanted gel (Image: Harvard Bio-Optics Lab)
Light can now be used to heal diabetes in mice. By implanting a transparent gel that contains genetically modified light-sensitive cells, researchers have demonstrated a new type of implant that could one day be used to treat disease and monitor toxins in people.

"Light is a great tool to interface with biological systems, but there is a fundamental problem. It gets scattered when it hits tissue, and at depths much thinner than our skin," says lead author Myunghwan Choi of Harvard Medical School in Boston.