Carbon nanohorns (CNH) were synthesized by a simple conventional hydrothermal method in this study. The CNHs were prepared by the chemical oxidation from the carbonation of Nafion (catalyst) with heparin (carbon resource). The formation of CNH involved two major steps, as described followed. First, the formation of carbon nanorice (CNR) was achieved by carbonation and self-assembly of heparin inside the Nafion structure. Second, the further oxidation of CNR resulted the heterogeneous and porous micelle domains showed at the outer layer of the CNR particles. These porous domains exhibited hydrophobic carbon and resulted self-assembly of the CNR to form the structure of CNHs. The resulting CNHs aggregated into a "dahlia-like" morphology with fluorescence in a diameter of 50-200 nm. The "dahlia-like" CNH showed better fluorescence (450nm) than CNR particles because of the presence of more structural defect. These findings suggest that the hydrophilic fluorescent carbon nanohorns (HFCNHs) synthesized in this study have the potential to be used for in vitro bio-imaging.
Keywords: bio-imaging; carbon nanohorn; hydrothermal method.