Establishment of electrochemiluminescence immunoassay to detect proinsulin levels in human serum

Abstract

Objective To establish a electrochemilumineecenee immunoaasay (ECLIA) for detecting proinsulin(PI) levels in human serum. Methods PI ECLIA kit contains biotinylated monoclonal insulin-specificantibody, ruthenium labeled monoclonal C-peptide specific antibody, and streptavidin-coated microparticlea. Its method performance, such as sensitivity, specific, accuracy, was evaluated. Then, the levels of PI in clinical samples were detected by ECLIA, including 44 type 2 diabetes and 60 healthy volunteers. Results Average recovery of ECLIA was 103. 8% with a lower detection limit of 0.38 pmol/L and biologic detection limit between 0.25 pmol/L and 0.5 pmol/L, and the function sensitivity was 0.5 pmol/L. The human insulin and human C-peptide did not cross-react at 500 μU/ml recovery of ECLIA was 103.8% with a lower detection limit of 0.38 pmol/L and biologic detection limit between 0.25 pmol/L and 0.5 pmol/L, and the function sensitivity was 0.5 pmoL/L. The human insulin and human C-peptide did not cross-react at 500 μU/ml and 450 ng/ml respectively. The total coefficient of variation of the ECLIA were leas than 5.0%, and the analytical measure range (AMR) was between 2.22 and 169.68 pmol/L. There was a good correlation (r=0.967,P=0.000) between ECLIA and radio immunoassay (RIA). The 95% reference value for human proinsulin was 1.07-15.54 pmol/L. The plasma levels of PI in type 2 diabetes were significantly higher than those in control healthy group[6.72(3.61-11.92) pmol/L vs 5.72(2.65-8.74) pmol/L, Z=-2.023, P<0.05]. Conclusions The monoclonal-based ECLIA is a sensitive, specific, and rapid method and no radiocontamination. It can be used to detect hanum serum proinsulin in type 2 diabetes. Key words: Proinsulin; Electrochemistry; Luminescence; Immunoassay