Microfluidic Immunoassay System for Rapid Detection and Semi-Quantitative Determination of a Potential Serum Biomarker Mesothelin.

Mesothelin (MSLN) is considered as a potential serological tumor biomarker for early diagnosis of pancreatic cancer. Nevertheless, low sensibility, high reagent consumption, and time costs of traditional detection methods limit their utility in clinical disease diagnoses. Here, we combined the immunoassay technique with microfluidic chips to develop a microfluidic immunoassay system (MIAS) that can be used for rapid semi-quantitative detection of serum MSLN levels. The MIAS was composed of 12 uniform structures, including 12 inlets, 12 reaction chambers, and one outlet allowing measurement of four samples with three repeats, simultaneously. A unique microarray cylinder was located at the end of each reaction chamber where immunoassay was performed to trap microspheres. A feasible interception efficiency (∼80%) was attained, with microspheres filling the reaction column. It has been demonstrated that fluorescence intensity is proportional to the MSLN concentration on the MIAS (R2 = 0.95). Subsequently, 16 clinical serum samples collected from Changhai Hospital, Shanghai were selected from eight patients with pancreatic cancers, four with pancreatitis, and four with other digestive system diseases (2 gastric cancer, 1 bile duct stricture, and 1 bile duct stones). MSLN levels for these samples were detected via MIAS. The results showed a significant correlation between MIAS and traditional enzyme-linked immunosorbent assay (ELISA), with the correlation coefficient, 0.93. The detection limit of MSLN fluorescence intensity and concentration was ∼6 a.u. and ∼20 pg/mL, respectively. The entire duration of analysis by MIAS decreased to ∼40 min compared to 2 h by ELISA. Statistical analysis of MIAS data revealed that MSLN was overexpressed in pancreatic cancer than in the others (P value = 0.0014). Moreover, the diagnostic accuracies of MSLN detected by MIAS and CA19-9 detected by ELISA in hospitals were 87.5 and 81.3%, respectively. MSLN is helpful for the early diagnosis of pancreatic cancer and other diseases, and it had a significant ability to discriminate between pancreatic and nonpancreatic cancers (P value = 0.0159). The results from this study show that MIAS has the potential to become a new serological tumor marker detection platform for rapid detection and semi-quantitative determination of MSLN and would have broad applications in early clinical diagnosis.