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Novel Magnetic Single-Walled Carbon Nanotubes/Methylene Blue Composite Amperometric Biosensor for DNA Determination

Abstract A single-walled carbon nanotube (SWNT)/nano-Fe3O4/methylene blue (MB) magnetic composite was developed to fabricate the DNA biosensor. The magnetic SWNTs/nano-Fe3O4 and SWNTs/nano-Fe3O4/MB composites were prepared by chemical coprecipitation and adsorption, respectively. The morphology, infrared, and magnetic properties of different composites were characterized. The behavior of MB adsorbed in the composite matrix as indicator for the detection of DNA was studied via MB reductive current changes between after and before combination with DNA. Owing to the high electrical conduction of SWNTs and superparamagnetism of Fe3O4 nanoparticles, the biosensor exhibited simple operation, high sensitivity, and easy renewal. The biosensor was successfully applied to detect the hybridization of DNA.