An Electrochemical Biosensor for Cardiac Troponin I Based on Electrocatalytic Activity Suppression of MIL-101 (Fe) by Immunoreaction

The metal-organic framework material of MIL-101 (Fe) with H2O2 mimicking enzyme activity was synthesized by a typical hydrothermal method. MIL-101(Fe) and cardiac troponin I antibody (anti-cTnI) were then successively immobilized on the surface of glassy carbon electrode that was pre-modified with amino-modified graphene (NH2-GR) through the covalent bonding. Thus, a novel MIL-101(Fe) /NH2-GR-based electrochemical sensing interface for cTnI was constructed. Electrochemical experiments showed that the immunoreaction between anti-cTnI and target cTnI on the sensing interface significantly suppressed the electrocatalytic activity of electrode-confined MIL-101(Fe) to H2O2, realizing the label-free analysis of cTnI. Under the optimal conditions, the catalytic current difference (Delta I) and the negative logarithm of the cTnI concentration (- lgC(cTnI)) showed a good linear relationship in the concentration range of 10 fg/mL-0.1 mu g/mL, and the detection limit was 3.1 fg/mL (S/N = 3). The constructed sensor was applicable for detection of cTnI in actual human serum samples, and the recoveries were 96.0% - 103.0%. The sensor exhibited good selectivity and reproducibility.

Automated summary

A novel electrochemical sensor based on MIL-101(Fe) /NH2-GR was successfully constructed for label-free detection of cTnI with a good linear range and low detection limit. The sensor showed good selectivity and reproducibility, and was applicable for detection of cTnI in human serum samples with high recoveries.