“…Although protein-based AQP4-IgG ELISA is easy to use, allows large-scale analysis, and can potentially be automated, having the potential to solve the criticisms of CBA, the sensitivity of ELISA can be affected by the expression, purification, and preservation strategy of the membrane protein AQP4. ,,, Specifically, surfactants are required to maintain the solubility of AQP4 for antigen and antibody interactions, but these compounds cannot prevent the aggregation of the membrane protein AQP4 during measurements, which accounts for the main reason for the low sensitivity of ELISA. , To address these issues, researchers have been focusing on the development of ELISA with extracellular loop peptides of AQP4 as substrates . However, synthetic peptides are short, rigid, and incapable of forming the tertiary structure with antigenicity, resulting in low sensitivity of peptide-based assays, which so far are not a valid alternative to CBA. ,, …”