Electrochemical detection of secreted alkaline phosphatase (SEAP) from transformed hela cells using a lab-on-a-chip device based on target concentration and local redox-cycling

This paper reports a lab-on-a-chip device having 256 individually addressable multi-detection points for high throughput single cell analysis. The chip is based on local redox-cycling and basically comprises 4 layers one on another. In order to fabricate individually addressable sensor points, two sets of microelectrode bands (row and column) were placed orthogonally to make 256 cross points where the sensor points are located. The chip device was then used to detect secreted proteins from single cells. First, the bottom surface of each detection point was modified with antibodies for the protein of interest and then single cells were captured in microwells at sensor points. The cells were incubated 4 h to secrete enough proteins to be immobilized. After which the cells were removed and the signal from the immobilized proteins were detected and amplified using redox cycling by setting the potential of electrodes to appropriate values. The results indicated that the secreted proteins were successfully detected using the chip device, which could be used for reporter gene assay and detection of some naturally secreted proteins.