Magnetophoretic Transport Line System for Rapid On-ChipAttomole Protein Detection.

A lab-on-a-chip traveling wave magnetophoresisapproach for sensitiveand rapid protein detection is reported. In this method, a chip-basedmagnetic microarray comprising lines of micrometer-sized thin filmmagnetic elements was used to control the movement of magnetic beads(MBs). The MBs and the chip were functionalized, forming a sandwich-typeassay. The MBs were transported across a detection area, and the presenceof target molecules resulted in the immobilization of MBs within thisarea. Target quantification was accomplished by MB counting in thedetection area using an optical microscope. In order to demonstratethe versatility of the microarray, biotinylated antiavidin was selectedas the target protein. In this case, avidin-functionalized MBs andan avidin-functionalized detection area were used. With a total assaytime of 1 to 1.5 h (depending on the labeling approach used), a limitof detection in the attomole range was achieved. Compared to on-chipsurface plasmon resonance biodetection systems, our method has a largerdynamic range and is about a factor of 500 times more sensitive. Furthermore,our MB transportation system can operate in any chip-based biosensorplatform, thereby significantly improving traditional biosensors. [ABSTRACT FROM AUTHOR]