Work

Dual-sensing θ-nanopipette enabling simultaneous and quantitative profiling of mitochondrial Zn2 + and Ca2+ at the single-cell level

Year: 2026

Type: article

Abstract: Metal ions homeostasis in mitochondria is tightly linked to cellular physiology and ischemic pathogenesis. Zn 2+ and Ca 2+ are two pivotal metal ions highly enriched in mitochondria, and their abnormal accumulation contributes to ischemic mitochondrial dysfunction and cell death. However, existing strategies struggle to track correlated Zn 2+ /Ca 2+ fluctuations in living mitochondria under ischemic‑mimicking conditions, which hinders direct observation of their coupled responses in a cellular model of cerebral ischemia. Herein, we develop a dual-sensing θ-nanopipette for label-free, simultaneous, and quantitative detection of mitochondrial Zn 2+ and Ca 2+ at the single-cell level. The θ-nanopipette integrates two independent channels: Channel Ⅰ employs Zn 2+ -specific aptamers and ionic current rectification (ICR) for Zn 2+ sensing with a detection limit of 10 pM, while channel Ⅱ utilizes a Ca 2+ -selective membrane for potentiometric detection of Ca 2+ down to 0.1 μM. This biosensor exhibits high selectivity, minimal invasiveness, and excellent stability for intracellular measurements. Using this platform, we reveal an approximate 8.5-fold overload of mitochondrial Zn 2+ and 10.5-fold overload of Ca 2+ in ischemic U87 cells. Furthermore, we achieve accurate monitoring of the ion changes during nimodipine intervention. This work provides a powerful subcellular electrochemical tool for dissecting metal ion networks in mitochondria, holding great potential for drug evaluation and disease mechanism studies.

Source: Sensors and Actuators B Chemical

DOI: 10.1016/j.snb.2026.140916