A Single Biosensor for Evaluating the Levels of Copper Ion and L‐Cysteine in a Live Rat Brain with Alzheimer's Disease

Abstract

AbstractCopper ion (Cu2+) and L‐cysteine (CySH) are closely correlated with physiological and pathological events of Alzheimer’s Disease (AD), however the detailed mechanism is still unclear, mainly owing to a lack of accurate analytical methods in live brains. Herein, we report a single biosensor for electrochemical ratiometric detection of Cu2+ and CySH in live rat brains with AD. N,N‐di‐(2‐picoly)ethylenediamine (DPEA) is first synthesized for specific recognition of Cu2+ to form a DPEA–Cu2+ complex. This complex shows high selectivity for CySH owing to the release of Cu2+ from the complex through CySH binding to Cu2+ center. In parallel, 5′‐MB‐GGCGCGATTTTTTTTTTTTT‐SH‐3′ (HS‐DNA‐MB, MB=Methylene Blue) is designed as an inner‐reference for providing a built‐in correction to improve the accuracy. As a result, combined with the amplified effect of Au nanoleaves, our single ratiometric biosensor can be successfully applied in real‐time detection of Cu2+ and CySH in the live rat brains with AD. To our knowledge, this is the first report on the accurate concentrations of Cu2+ and CySH in live rat brains with AD.