Levels of neurotransmitters in the brain can indicate neurodegenerative disorders such as Alzheimer’s disease. However, the blood-brain barrier (BBB) prevents efficient delivery to the brain of aptamer-based fluorescent sensors. Researchers used brain-cell derived exosomes to package ATP-responsive aptamer sensors for easier transfer across the BBB in mouse models of Alzheimer’s disease, enabling improved brain imaging. The team suggests that with further development technology could help advance Alzheimer’s disease diagnosis and treatment.