Peptide Sequence Modulating the Analytical Performance of Electrogenerated Chemiluminescence Peptide-Based Biosensors...

Electrogenerated chemiluminescence (ECL) methods have been widely used in clinical diagnosis. Although ECL peptide-based biosensors continue to grow with good sensitivity and signal flexibility, little emphasis has been placed on the effect of the peptide sequence on ECL sensitivity. We herein studied the nuanced effects of different peptide sequences on the analytical performance of ECL peptide-based biosensors for matrix metalloproteinase 2 (MMP-2) assay, in which [(pbz)₂Ir(DMSO)Cl] (pbz = 3-(2-pyridyl)benzoic acid) was used as the ECL emitter while a specific peptide was used as the molecular recognition element. [(pbz)₂Ir(DMSO)Cl] was labeled onto the peptide by a coordination-based site-specific labeling strategy to form the ECL probe. It was found that the incorporation of one histidine (H) or two H at the terminal of the peptide resulted in a significant increase in ECL signal and a negligible effect on the cleavage ability of the ECL probe while the incorporation of H at the middle of the peptide caused a slight increase of ECL signal and a significant inhibitory effect on the cleavage ability of the ECL probe. One type of ECL peptide-based biosensor was fabricated for the determination of MMP-2 at gold nanoparticle-modified glassy carbon electrode. MMP-2 can be detected with a detection limit of 0.9 ng/mL, and it can be applied to detect MMP-2 in serum samples and cell secretions. This work provides some information for the synthesis of efficient ECL probe and for the design of ECL peptide-based biosensors, which are promising in clinical diagnosis.