Dielectrophoretic formation of cell-particle complexes based on immunoreaction

We applied a rapid and simple fabrication method of the island pattern of particles and cells to discriminating cells with specific surface antigen. The Upper interdigitated microband array (IDA) electrode was mounted on the lower substrate with the same design to fabricate a microfluidic-channel device for dielectrophoretic manipulation. Grid formation of electrodes was fabricated by rotating the upper template IDA by 90° relative to the lower IDA. A suspension of particles modified with anti-CD33 antibody or/and HL60 cells was introduced into the channel. AC electric signal (typically 20 V peak-to-peak, 100 kHz) was then applied to the bands on the upper and lower IDA, resulting in the formation of island patterns at the intersections with low electric fields. The accumulated particles and cells were fixed to produce the complexes through the immunoreactions between the antibody immobilized on the particle and CD33 on the cell surface. The complexes were only produced by the corresponded pair of antigen-antibody. It is noted that the time required for single sensing is as short as 6 min in the presented procedure. Furthermore, the present method for a novel cell binding assay does not require pretreatment such as target labeling or washing of unbound cells.