Autoimmune diseases, cancers, and viral infections pose significant global health threats, characterized by chronic pathology, unregulated cellular proliferation, and rapid transmission, respectively, requiring urgent early warning and treatment strategies. Antibodies, primarily classified into autoantibodies and therapeutic antibodies based on their clinical roles, provide essential information and show considerable value in the precise diagnosis and treatment of these serious diseases. Among the technologies utilized in bioanalysis, electrochemical biosensors, with their unique advantages of rapid response, high sensitivity, miniaturization, cost-effectiveness and user-friendly operation, have been developed as a trending technology for precise diagnostic and therapeutic drug monitoring. This review systematically summarizes the relationships and roles of clinically relevant antibodies in autoimmune diseases, cancers, and viral infections, while detailing the composition, strategies, development, and application trends of relevant electrochemical biosensors. Furthermore, it highlights the remaining challenges and opportunities for the advancement and prospects of electrochemical sensors in the context of clinically relevant antibodies.

The dynamic tracking of antibody‒drug conjugates (ADCs) in serum is crucial. However, a versatile bioanalytical platform is lacking due to serious matrix interferences, the heterogeneity and complex biotransformation of ADCs, and the recognition deficiencies of traditional affinity technologies. To overcome this, a multiepitope recognition technology (MERT) was developed by simultaneously immobilizing CDR and non-CDR ligands onto MOF@AuNPs. MERT's excellent specificity, ultrahigh ligand density, and potential synergistic recognition ability enable it to target the different key regions of ADCs to overcome the deficiencies of traditional technologies. The binding capacity of MERT for antibodies is ten to hundred times higher than that of the mono-epitope or Fc-specific affinity technologies. Since MERT can efficiently capture target ADCs from serum, a novel bioanalytical platform based on MERT and RPLC‒QTOF-MS has been developed to monitor the dynamic changes of ADCs in serum, including the fast changes of drug-to-antibody ratio from 3.67 to 0.22, the loss of payloads (maytansinol), and the unexpected hydrolysis of the succinimide ring of the linker, which will contribute to clarify the fate of ADCs and provide a theoretical basis for future design. In summary, the MERT-based versatile platform will open a new avenue for in-depth studies of ADCs in biological fluids.

Tea is a widely consumed beverage and has many important physiological properties and potential health benefits. In this study, a novel method based on supercritical fluid chromatography coupled with mass spectrometry (SFC-MS) was developed to simultaneously determine 11 amino acids in different types of tea (green teas, Oolong tea, black tea and Pu-erh tea). The separation conditions for the analysis of the selected amino acids including the column type, temperature and backpressure as well as the type of additive, were carefully optimized. The best separation of the 11 amino acids was obtained by adding water (5％, v/v) and trifluoroacetic acid (0.4％, v/v) to the organic modifier (methanol). Finally, the developed SFC-MS method was fully validated and successfully applied to the determination of these amino acids in six different tea samples. Good linearity (r ! 0.993), precision (RSDs 2.99％), accuracy (91.95％e107.09％) as well as good sample stability were observed. The limits of detection ranged from 1.42 to 14.69 ng/mL, while the limits of quantification were between 4.53 and 47.0 ng/mL. The results indicate that the contents of the 11 amino acids in the six different tea samples are greatly influenced by the degree of fermentation. The proposed SFC-MS method shows a great potential for further investi-gation of tea varieties.