Development of a myoglobin impedimetric immunosensor based on mixed self-assembled monolayer onto gold

Immunosensors rely on antibody-antigen binding with a range of possible detection methodologies. In this study, electrochemical impedance spectroscopy was used to monitor the sensor surface assembly and recognition of the analyte (myoglobin). Myoglobin is rapidly released into the circulatory system after an acute myocardial infarction and rapidly rising levels make it the first biochemical marker of myocardial damage. The immunosensor fabrication steps comprised the steps of (a) formation of mixed self-assembled monolayers (mSAM) on gold electrodes using a mixture of biotinyl-phospholipid and mercaptohexadecanoic acid; (b) neutravidin functionalisation and (c) attachment of biotinyl anti-myoglobin antibodies. A range of analyte concentration (10(-12)_ 10(-6) M) was successfully detected in phosphate buffered saline and in serum concentration ranging from 10% (v/v) to 100% (v/v) serum. Quartz crystal microbalance and atomic force microscopy studies were carried out to study each step of fabrication to elucidate binding characteristics and surface topography.