Liquid crystal and gold nanoparticles applied to electrochemical immunosensor for cardiac biomarker.

A label-free electrochemical immunosensor based on the ionic liquid crystal (E)-1-decyl-4-[(4-decyloxyphenyl)diazenyl]pyridinium bromide (Br-Py) coated on a glassy carbon electrode (GCE) for the quantitative detection of myoglobin (Mb), a cardiac marker for acute myocardial infarction, is reported herein for the first time. The monoclonal anti-myoglobin antibody (ab-Mb) was covalently immobilized using glyoxal on a film of polyethyleneimine-coated gold nanoparticles (AuNP-PEI). The proposed method for Mb detection is based on voltammetric suppression of the Br-Py signal when the immunosensor was incubated with Mb antigen. The electrochemical performance of the Mb immunosensor was studied by electrochemical impedance spectroscopy, and cyclic and square-wave voltammetry. Under the optimal conditions, the proposed immunosensor shows a good linear relationship between the electrochemical inhibition response and the concentration of Mb over the range of 9.96-72.8 ng mL(-1) with a detection limit of 6.29 ng mL(-1). The results obtained indicate that the proposed immunosensor provides good sensitivity and simple operation for detecting acute myocardial infarction with Mb as a biomarker.