Real-time Tracking and Sensing of Cu+ and Cu2+ with a Single SERS Probe in the Live Brain: Toward Understanding Why Copper Ions Were Increased upon Ischemia.

The imbalance of Cu+ and Cu2+ in the brain is closely related to neurodegenerative diseases. However, it still lacks of effective analytical methods for simultaneously determining the concentrations of Cu+ and Cu2+ . Herein, we created a novel SERS probe (CuSP) to real-time track and accurately quantify extracellular concentrations of Cu+ and Cu2+ in the live brain. The present CuSP probe demonstrated specific ability for recognition of Cu+ and Cu2+ in a dual-recognition mode. Then, a microarray consisting of 8 CuSP probes with high tempo-spatial resolution and good accuracy was constructed for tracking and simultaneously biosensing of Cu+ and Cu2+ in the cerebral cortex of living brain. Using our powerful tool, it was found that that the concentrations of Cu2+ and Cu+ were increased by ≈4.26 and ≈1.80 times upon ischemia, respectively. Three routes were first discovered for understanding the mechanisms of the increased concentrations of Cu+ and Cu2+ during ischemia.