Disclosed herein is a particle comprising a magnetic material and a carbon layer on the outer surface of the magnetic material. The carbon layer may comprise graphite, such as Graphite from the University of Idaho Thermolyzed Asphalt Reaction (GUITAR). The particle may further comprise a single stranded nucleic acid moiety, such as single stranded DNA or single stranded RNA, conjugated to the carbon layer. The disclosed particles are useful as nucleic acid sensors, PCR reagents, and in nucleic acid synthesis applications.