Potassium ion (K⁺) is widely involved in several physiopathological processes, and its abnormal changes are closely related to the occurrence of brain diseases of cerebral ischemia. In vivo acquirement of K⁺ variation is significant to understand the roles of K⁺ playing in brain functions. A microelectrode based on single-stranded DNA aptamers was developed for highly selective detection of K⁺ in brain, in which the aptamer probes were designed to contain an aptamer part for specific recognition of K⁺, an alkynyl group used for stable confinement of aptamer probe on the gold surface, and an electrochemical redox active ferrocene group to generate current response signal. The response range of the microelectrodes could be rationally tuned by varying the chain length of the aptamer probe. The optimized electrode, LAC, displayed high selectivity for in vivo detection of K⁺, and suitable linear range from 10 μmol·L^–1–10 mmol·L^–1, which could fulfill the requirement of K⁺ detection in brain. Eventually, the microelectrodes were successfully applied for the detection of K⁺ in the living mouse brains followed by hypoxic.

As an important neurotransmitter, the detection of dopamine (DA) is of great significance for the diagnosis and treatment of neurological diseases. In this study, WO₃-SnO₂ nanoflake arrays were synthesized on fluorine-doped tin oxide (FTO) by hydrothermal synthesis and pulse electrodeposition, revealing significant surface-enhanced Raman scattering (SERS) activity with an enhancement factor (EF) reaching 4.79 × 10⁷. The obvious EF was mainly ascribed to the charge transfer between WO₃-SnO₂ and methylene blue (MB) based on chemical mechanism (CM) and the molecular resonance effect. With the competitive adsorption of DA and absorbed MB, we prepared a SERS and electrochemical (EC) dual-mode detection platform of DA based on the WO₃-SnO₂ nanoflake arrays. The linear range (LR) was 5.00–1.75 × 10³ nmol/L, and the detection limits (LODs) were as low as 1.50 and 0.80 nmol/L by SERS and EC respectively. Besides, the developed detection platform can shield the interference of many neurotransmitters similar to DA, showing good selectivity and excellent stability. In general, the SERS-EC dual-mode detection platform can be well applied to the detection of DA in cell lysate, demonstrating great potential in diagnosis of neurodegenerative diseases.

Designing electrochemical interfaces for in vivo analysis of neurochemicals with high selectivity and long-term stability is vital for monitoring dynamic variation and dissecting the complex mechanisms of pathogenesis in living animals. This review focuses on the development of electrochemical interfaces based on rational design of molecular probes for in vivo measurement with high selectivity and high stability from three aspects: (1) Specific recognition probes were rationally designed and created to remarkably improve the selectivity of in vivo analysis in a complicated brain environment. (2) The Au-C≡C functionalized surface was developed to remarkably enhance the stability of molecular assembly, and employed for real-time mapping and accurate quantification in the brains. (3) Combined with the Au-C≡C functionalized molecular probe, the new type anti-biofouling microfiber array was established to achieve long-term and real-time monitoring dynamic changes in the brain. At last, some perspectives are highlighted in the further development of the efficient electrochemical interfaces for in vivo detection in the brain.