J-aggregates are an attractive supramolecular structure with interesting excitation properties found in the light-harvesting antenna of green sulfur bacteria. To structurally mimic the light-harvesting antenna, we synthesize J-aggregate nanotubes with a sharp and intense absorption band (J-band) by the coassembly of lithocholic acid (LCA) and 3,3'-dipropylthiadicarbocyanine iodide (DiSC(3)(5)) in aqueous solution. We show that the J-aggregate nanotubes can be used as a supramolecular probe for the sensitive and selective detection of dopamine (DA) in phosphate buffered saline (PBS) solution with the detection limit of similar to 0.4 nM by simply observing the intensity change of the J-band due to the efficient photoinduced electron transfer from the J-aggregate nanotubes to the adsorbed DA.