Detection of K-Ras oncogene using magnetic beads-quantum dots in microfluidic chip.

Recently quantum dots (QDs) have been extensively used in the field of biotechnology. QDs have merits of wide selection of emission wavelength and exceptional stability against photo bleaching over conventional organic fluorophores and are used in cell imaging, biomarker, and fluorescence resonance energy transfer (FRET) sensor. Magnetic beads have been used as solid support in microfluidic devices to trace bio-molecules. In this study, Polydimethylsiloxane (PDMS) based microfluidic chips were prepared for the detection of K-Ras oncogene by using QDs-DNA conjugate. K-Ras oncogene can be detected by fluorescence quenching in microfluidic chip. Carboxylated CdSe/ZnS QDs (emission wavelength: 605 nm) could bind to magnetic beads of polystyrene/divinyl benzene via EDC/NHS crosslinking reaction. The fluorescence from QDs could be quenched by intercalating dye (thiazol orange dimers: TOTO-3) after hybridization with target DNA and probe DNA in the channel of microfluidic chip. The fluorescence intensity change of QDs after hybridization in microfluidic chip has been studied.