Archaea-Inspired Switchable Nanochannels for On-Demand Lithium Detection by pH Activation

With the rapid development of the lithium ion battery industry, emerging lithium (Li) enrichment in nature has attracted ever-growing attention due to the biotoxicity of high Li levels. To date, fast lithium ion (Li⁺) detection remains urgent but is limited by the selectivity, sensitivity, and stability of conventional technologies based on passive response processes. In nature, archaeal plasma membrane ion exchangers (NCLX_Mj) exhibit Li⁺-gated multi/monovalent ion transport behavior, activated by different stimuli. Inspired by NCLX_Mj, we design a pH-controlled biomimetic Li⁺-responsive solid-state nanochannel system for on-demand Li⁺ detection using 2-(2-hydroxyphenyl)benzoxazole (HPBO) units as Li⁺ recognition groups. Pristine HPBO is not reactive to Li⁺, whereas negatively charged HPBO enables specific Li⁺ coordination under alkaline conditions to decrease the ion exchange capacity of nanochannels. On-demand Li⁺ detection is achieved by monitoring the decline in currents, thereby ensuring precise and stable Li⁺ recognition (>0.1 mM) in the toxic range of Li⁺ concentration (>1.5 mM) for human beings. This work provides a new approach to constructing Li⁺ detection nanodevices and has potential for applications of Li-related industries and medical services.