Study on the Process and Reagents of Carboxyl Latex Microsphere Coupled Chitosanase 3-Like Protein 1 Antibody

A method for quantitatively measuring the content of chitosanase 3-like protein 1 (CHI3L1) in human serum, applicable to both fully automatic biochemical analyzers and specific protein analyzers, has been developed. This method can assist in diagnosing liver diseases such as cirrhosis and liver fibrosis. The method's performance was evaluated to ensure it meets clinical diagnostic requirements. Using chemical covalent coupling technology, CHI3L1 monoclonal antibodies were covalently coupled with carboxylated latex microspheres. By optimizing coupling conditions, such as the antibody-to-microsphere ratio, activator concentration, and coupling buffer solution, the antibodies were fixed and uniformly coated on the microspheres' surface. This resulted in an immunogel system with specific steric hindrance effects and antigen-binding activity. The optimal gel turbidity reagent preparation process was then selected. The method's detection limit, sensitivity, precision, recovery, linear range, clinical reportable range, biological reference interval, and interference resistance were evaluated. The results were compared with those from chemiluminescent immunoassays on fully automatic biochemical analyzers and specific protein analyzers. Using an antibody-microsphere ratio of 40μg/mg, an activator concentration of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (1-ethyl-(3-dimethylaminopropyl)carbodiimide) at 30μg/mg, and a coupling buffer of 20 mmol/L 4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid buffer, the optimal immunogelatin reagent was obtained. Performance tests showed a detection limit of 5 ng/mL, a precision of less than 3%, a linear range of up to 1200 ng/mL, and an average recovery rate of 97.3%. Hemoglobin, triglycerides, bilirubin, and rheumatoid factor in the sample did not significantly interfere with the CHI3L1 test results. The overall agreement between the reagent and chemiluminescence immunoassay on biochemical analyzers and specific protein analyzers was 93.17% and 93.65%, respectively. The linear regression equations were y1 = 0.9809x1 + 2.0764 and y2 = 0.9608x2 + 2.2587, with correlation coefficients R2 of 0.9975 and 0.9969, indicating good correlation between the reagent and chemiluminescence results on both types of instruments. The process developed in this study can serve as a preparation condition for the CHI3L1 reagent, providing a more stable and efficient method for CHI3L1 clinical testing, which is significant for the diagnosis and monitoring of related diseases. In-depth research on the coupling process provides important theoretical foundations and practical references for the development of biomarker detection reagents.