Multidimensional Unraveling Insights from an Enzyme-Nanozyme Cascade-Based Electrochemical Biosensor for Screening Microplastic Neurotoxicity.

Accurate quantification of biomarkers is crucial for evaluating the neurotoxicity of pollutants. Traditional detection methods, albeit important, are limited by single analytical indicators and time-consuming procedures, which lead to distorted detection results for biomarkers with high metabolic rates. Herein, a multiplexed electrochemical sensing array was designed based on nanozyme capsules; this metal-porphyrin-structured covalent-organic framework embedded with enzymes simultaneously detected H2O2, acetylcholine (ACh), and glucose (Glu). The nanozyme capsule not only exhibits peroxidase-like activity for the sensitive detection of H2O2 but also serves as a carrier to encapsulate enzymes within its cavities, forming a cascade catalytic system for the specific recognition of ACh or Glu. This sensor features a broad detection range, low detection limits, and a strong anti-interference capability. More importantly, it can rapidly quantify three easily degradable biomarkers in neuronal lysates within 3 min without pretreatment. With the sensor, we multidimensionally assessed and differentiated the effects of different microplastics (MPs) based on the ability of neurons to produce ACh and H2O2 as well as their glucose uptake capacity. Furthermore, it is found that MPs induce stronger neurotoxic effects under hyperglycemia. This study not only provides an effective tool for determining multiple easily degradable biomarkers but also offers technical support for assessing the health risks of pollutants.