An implantable micro imaging device for molecular imaging in a brain of freely-moving mouse

We have developed an implantable micro imaging device that can observe specific molecules such as neuropsin in the deep brain of a freely-moving mouse with minimal invasiveness. A chemical substance, 4-methylcoumaryl-7-amide (MCA), which reacts with neuropsin and changes to fluorophore, 7-amino-4-methyl coumarin (AMC), is injected by a specially designed cannula employed with the device. The implanted sensor can measure spatio-temporal dynamics of neuropisn through fluorescence of AMC, which is accompanied by specific behavior in artificially induced epilepsy. The damage induced by the implantation of the device has been investigated. Four weeks after the implantation, no connective tissues are observed at the implanted locations and imaging was successfully conducted. Immuno-staining of the brain after the implantation reveals that the damage area is limited in less than 100 μm from the sensor surface.