Some medicines are more effective when they are delivered at the site where they are needed and when they are needed. Think about taking an aspirin but it works only when you have a headache. Scientists from 
have developed a biodegradable material with nanometer-scale gold particles that help release medicines embedded in the material. When you shine an infrared light on the material, the gold particles heat up the biodegradable material and release the medicine. Near infrared-wavelength light is used because it can penetrate a lot deeper into the body than regular visible light. These biodegradable materials might be implanted into the body and then release important medicines on demand
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