Abstract
OBJECTIVE: Abnormal serum matrix metalloproteinase-9 (MMP-9) levels are closely related to the occurrence and development of many diseases. This study aimed to establish a fluorescence immunochromatography (FIC) method using the lanthanide fluorescent element europium(III) (Eu(3+)) for the quantitative measurement of MMP-9 in serum. DESIGN & METHODS: The FIC method for quantifying MMP-9 was optimized and established, and the FIC test strips (FICTS) were assembled and subsequently evaluated for sensitivity, specificity and precision. Furthermore, the reference interval and clinical sensitivity/specificity were estimated using clinical healthy/positive serum samples, and a commercial ELISA was used for comparison. RESULTS: We successfully established an FIC method and prepared FICTS. The analytical sensitivity of the FICTS was 0.92 ng/mL, with a linearity range of 0-1000 ng/mL. The cross-reactivity of the 7 common serum interferents was less than 1.56%. All recoveries of the intra-array and inter-array samples ranged from 102.50% to 110.99%, and all CVs were less than 5%. The reference interval of the FICTS was >161.15 ng/mL. The clinical sensitivity was 96.00%, and the specificity was 97.5%. The results of 270 clinical serum samples were highly coincident with the clinical diagnostic results. Pearson correlation analysis and Bland‒Altman plots indicated that the FICTS and commercial ELISA results were consistent with the quantitative MMP-9 concentration. CONCLUSIONS: The designed FIC method and test strips may be suitable for point-of-care quantitative measurement of MMP-9, which provides a new method for screening for atherosclerosis, xerophthalmia, etc.