Rapid and sensitive homogenous detection of the Ibaraki virus non-structural protein using magnetic modulation biosensing system

Magnetic modulation biosensing (MMB) system rapidly and homogeneously detected coding sequences of the nonstructural Ibaraki virus protein 3 (NS3) complementary DNA (cDNA). A novel fluorescent resonance energy transfer (FRET)-based probe discriminated the target DNA from the control. When the target sequence is detected, the FRETbased probe is cleaved using Taq-polymerase activity and upon excitation with a laser beam fluorescent light is produced. The biotinylated probes are attached to streptavidin-coupled superparamagnetic beads and are maneuvered into oscillatory motion by applying an alternating magnetic field gradient. The beads are condensed into the detection area and their movement in and out of an orthogonal laser beam produces a periodic fluorescent signal that is demodulated using synchronous detection. Condensation of the beads from the entire volume increases the signal while modulation separates the signal from the background noise of the non-magnetized solution. 1.9 picomolar of the Ibaraki virus NS3 cDNA was detected in homogeneous solution within 18 minutes without separation or washing steps. In this paper we will review the magnetic modulation system and present its capability in specific DNA sequences detection.