Carbon nanospheres for fluorescent biomolecular detection

In this article, we demonstrate the facile preparation of carbon nanospheres on a large scale by treating graphite with chlorosulfonic acid and their use as very effective quenchers for highly sensitive and selective nucleic acid and thrombin detection. The detection is accomplished by two steps: (1) a carbon nanosphere (CNS) adsorbs and quenches the fluorescence of a dye-labeled single-stranded DNA (ssDNA) probe; (2) in the presence of a target, the biomolecular mutual interaction suppresses fluorescence quenching, which makes the ssDNA detach from the CNS surface, leading to recovery of the dye fluorescence.