A SERS Optophysiological Probe for the Real‐Time Mapping and Simultaneous Determination of the Carbonate Concentration and pH Value in a Live Mouse Brain

Abstract To have a profound understanding of the physiological and pathological processes in a brain, both chemical and electrical signals need to be recorded, but this is still very challenging. Herein, micrometer‐ to nanometer‐sized SERS optophysiological probes were created to determine both the CO 3 2− concentration and the pH in live brains and neurons because both species play important roles in regulating the acid–base balance in the brain. A ratiometric SERS microarray of eight microprobes with tip sizes of 5 μm was established and used for the first time for real‐time mapping and simultaneous quantification of CO 3 2− and pH in a live brain. We found that both the CO 3 2− concentration and the pH value dramatically decreased under ischemic conditions. The present SERS technique can be combined with electrophysiology without cross‐talk to record both electrical and chemical signals in brains. To deepen our understanding of the mechanism of ischemia on the single‐cell level, a SERS nanoprobe with a tip size of 200 nm was developed for use in a single neuron.