Potential applications of graphene in nanoelectronics and composites have been actively pursued. However, the biological applications of graphene remain largely unexplored. Graphene is a single atom sheet of sp2 bonded carbon atoms in a closely packed honeycomb structure. It is one of the most attractive nanostructured materials, with physical, chemical and biological applications. Graphene combines surface stability with high corrosion resistance and biotolerance, which are ideal features for medical applications, such as the construction of biosensors, biomaterials, and medical implants.
For several decades, the field of point-of-care biosensing has been dominated by lateral-flow chromatographic strips, which has been based on the continuous transport of sample fluid through a porous medium driven by capillary forces. And fluorescent labeling-based platforms are normally used despite many methods are available to detect the biomolecules. However these lateral-flow and fluorescent labeling technologies cannot be served all of the needs of point-of-care fields. The pores prevent the movement of particles and biomaterials because the particles and biomaterials adhere inside the pores. And the effective labeling steps instead of fluorescent labeling are required to produce a portable biosensors providing a simple, accurate, stable, and inexpensive platform for patient diagnosis. Magnetoelectronics has attracted an attention for development of biosensor because magnetoresistive(MR) detection using magnetic particles has shown high sensitivity, and inexpensive device. Magnetic nanoparticles(MNPs) have found wide-ranging applications such as magnetic resonance imaging(MRI) contrast agents, magnetic separation, targeted drug delivery, and biological sensing agents. And the nanomagnetic labels for biosensing have several potential advantages. Because the nanomagnetic labels are not affected by reagent chemistry or a light source. Furthermore, magnetic fields are not screened by obstacles such as aqueous reagents or biomaterials, and easy transfer of magnetic particles by external magnetic field.
Recently, there have been many studies of cell proliferation and differentiation on carbon materials. The proliferation and differentiation of cells largely depends on the physical, chemical and mechanical properties of the surface on which they are cultured.
In this work, we demonstrate the DNA sensor, which detect the specifically sequenced DNA by using the giant magnetoresistance(GMR) sensor and a graphene sheet instead of the conventionally used fluorescent labeling and lateral-flow chromatographic strips. The detection of DNA relies on the sensing of hybridization between probe DNA and its complementary target DNA. The MNPs were used as a label on target DNA. The commercially available γ-Fe2O3 nanoparticles have been modified with functional organic molecules having carboxyl group to be labeled target DNA. The graphene sheet was functionalized with fluorine to passivate from the physical adsorption of probe DNA or MNPs-labeled target DNA. And graphene sheet was partially oxygenated with micro-size. We immobilized probe DNA on the oxygenated graphene sheet and hybridized with MNPs-labeled complementary or noncomplementary target DNA. And the detection of complementary DNA was evaluated by the giantmagnetorsistance(GMR) sensor.
We evaporated gold to fabricate metal electrode on graphene sheet. And we seed the SH-SY5Y cell between two gold electrodes and apply electrical stimulation on two electrodes at graphene sheet. The morphology, proliferation, and differentiation of SH-SY5Y cell are affected by electrical stimulation on the graphene sheet. We can control the morphology, proliferation, and differentiation of cells using electrical stimulation, artificially.