Responses of label-free metallothionein sensor immobilized with thiolated antibody

Metallothionein (MT) is a low molecular weight metalloprotein that is induced by extraneously introduced heavy metals to the blood and organs of living organisms and is generally regarded as a useful biomarker of possible heavy metal contamination. In this study, a polyclonal anti-rabbit MT antibody was manufactured using a high-purity MT antigen and exploited as the biological component to develop a label-free quartz crystal microbalance immunosensor via the thiolation with sulfosuccinimidyl 6-[3-(2-pyridyldithio)propionamido]hexanoate. When measured at each step of antibody immobilization by the batchwise operation using a dip cell, the biggest sensor response was obtained in the case of the whole course of immobilization, which indicated that the immobilization procedure of this study was effective and the obtained sensor signal was the output of the corresponding immune reaction. When determined for MT at two antibody dilutions for immobilization, concentration-dependent sensor responses were more conspicuous at the antibody dilution of 1:5 and the limit of detection of 20 ng/mL was observed.

► A label-free quartz crystal microbalance immunosensor chip was produced exploiting a home-made anti-MT antibody via the antibody thiolation with sulfosuccinimidyl 6-[3-(2-pyridyldithio)propionamido]hexanoate.
► When measured at each step of antibody immobilization, the biggest sensor response was obtained in the case of the whole course of immobilization.
► The concentration-dependent sensor responses were more conspicuous at the antibody dilution of 1:5 compared to that of 1:2.
► At this condition, the limit of detection for MT, a biomarker protein for heavy metals, was 20 ng/mL.