Graphdiyne oxide enhances the stability of solid contact-based ionselective electrodes for excellent in vivo analysis

Quantitively and stably tracking ion dynamics in the living brain of animals is essential to understanding many physiological and pathological processes. Solid-state ion-selective electrodes (ISEs) are powerful tools for monitoring the dynamic change of ions at physiological concentration range; however, the unintentional accumulation of an aqueous layer at the ion selective membrane/ solid contact interface compromises the electrode potential stability, limiting its in vivo application. Here, using manganese dioxide (MnO2) and potassium ISE (K+-ISE) as model solid contact and ISEs, we demonstrate for the first time that graphdiyne oxide (GDYO) can enhance the potential stability of solid contact-based ISEs. Our results suggest that the intrinsic structural and hydrophobic features of GDYO, plays a key role in impeding and stabilizing the formation of water layer. With GDYO-MnO2 acting as the solid contact, the K+-ISE displays an excellent short-term potential stability and maintains great selectivity, achieving reliable K+ sensing at the animal level. The GDYO-based strategy is generalizable to different ISEs and does not require complicated processing steps, paving an exciting opportunity for in vivo ion recognition and sensing.