Implantable electrode-based in vivo electrochemical sensing research has consistently played a pivotal role in driving advancements in analytical methods within the field of neurochemical research. The intricacies of brain structures and the real-time nature of various physiological activities impose rigorous demands on analytical approaches. High specificity, elevated sensitivity, robust interference resistance, and favorable biocompatibility are essential prerequisites for in situ analysis in living systems. With the development of novel functional materials and advancements in electrochemical research methodologies, there has been significant progress in the field of in vivo electrochemical analysis employing implantable electrodes. Nonetheless, this field continues to encounter a series of challenges. This article reviews the current applications of implantable electrodes, such as enzyme-modified electrodes, aptamer-modified electrodes, ion-selective electrodes, liquid-liquid interface-based electrodes, and ion current rectifying electrodes in the field of in vivo electrochemical sensing, as well as the major progress in the research of their key properties such as biocompatibility and sensitivity. The intention is to offer valuable insights for future research in precision detection within the intricate environment of the brain.

Although nanozyme has become an emerging area of research attracting extensive attention recently, the activity and specificity of currently reported nanozymes are generally lower than those of natural enzymes. Developing highly active and specific nanozymes is therefore extremely necessary and also remains a great challenge. Superoxide dismutase (SOD) catalyzes the disproportionation of cytotoxic O₂^·− into hydrogen peroxide and oxygen, and plays an important role in reducing human oxidative stress. In this work, we prepare Cu single-atom catalysts (Cu/GO SACs, GO = graphene oxide) through a simple and low-cost strategy at room temperature using Cu foam and graphene oxide. Cu/GO SACs can maintain excellent catalytic activity under harsh environment. Compared with the natural enzyme, SOD-like Cu/GO SAC nanozyme has higher catalytic activity and meanwhile, it does not possess the common properties of other mimic enzymes often existing in nanomaterials. Based on the excellent SOD-like enzyme activity of Cu/GO SACs, it successfully eliminates the active oxygen in cigarette smoke. This work not only provides a new idea for the design and synthesis of nanozymes with excellent SOD mimetic properties, but also is promising in the treatment of lung injury and inflammatory diseases related to free radical production.