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Root rot is a highly infectious disease in traditional Chinese medicine (TCM) that spreads quickly and significantly affects the yield and quality of TCM. Therefore, there is an urgent need for accurate and convenient early warning technology to guide root rot control. The root rot of TCM is mainly caused by Fusarium fungi infecting plants. After plants have been infected with fungi, zearalenone (ZEN), fumonisin (FB), fusarium acid (FA), and other compounds will produce duo to Fusarium infects plants to promote metabolism. And the trace expression of these compounds in plants is used as root rot early warning markers (RREWM). Herein, an electrochemical immunosensor was developed for the rapid, convenient, and sensitive detection of zearalenone (ZEN), an early warning marker for Radix isatidis root rot. The immunosensor utilizes Fe3O4@g-C3N4 composite ITO electrode. Initially, the ITO conductive films were modified with Fe3O4@g-C3N4 and gold nanoparticles (AuNPs) through droplet coating and chemical deposition, respectively. Subsequently, the AuNPs were conjugated with zearalenone antibody (ZEN-Ab) to generate high affinity sulfhydryl-bound recognition elements. Under the optimized condition, the sensor demonstrates a linear wide range of 10.00 pg mL−1 to 1.20 × 104 pg mL−1 with a LOD of 3.86 pg mL−1. Additionally, the sensor showed good reproducibility and stability. This study exhibits a convenient, accurate, and low-cost method for detecting early warning markers of root rot in TCM cultivation, which was expected to provide a reliable warning technology for the early warning and prevention of diseases in the planting process of TCM. [ABSTRACT FROM AUTHOR]

A novel electrochemical immunosensor was developed for highly sensitive detection of brain-derived neurotrophic factor (BDNF), a well-known depression marker. The immunosensor was fabricated by modifying indium tin oxide-coated polyethylene terephthalate (ITO-PET) with N-doped graphene-polyaniline (NG-PANI) and gold nanoparticles (AuNPs) to enhance the conductivity and protein loading capacity. Subsequently, BDNF was immobilized onto the electrode surface via gold-sulfur bonds, followed by the attachment of biotinylated antibody (Biotin-Ab) and horseradish peroxidase-avidin (HRP-Avidin) to create the final immunosensor (HRP-Avidin–Biotin-Ab-BDNF-AuNPs/NG-PANI/ITO-PET). The proposed immunosensor exhibited a linear range of determination (0.781–400 pg/mL) with a low limit of detection (LOD) of 0.261 pg/mL (S/N = 3) and excellent reproducibility (RSD = 1.4%) and stability (92.7%, RSD = 3.1%). Additionally, the immunosensor demonstrated good anti-interference performance and good recovery (98.1–107%). To evaluate the practical utility of the immunosensor, BDNF levels were quantified in the serum of mice with depression induced by chronic unpredictable mild stress (CUMS). The results indicated that the serum BDNF levels were significantly decreased in the depression model group compared with the control group, highlighting the potential of this immunosensor for clinical detection of BDNF in depression diagnosis and treatment. [ABSTRACT FROM AUTHOR]