We report cellphone-based detection of dopamine with attomolar sensitivity in clinical samples with the use of a surface plasmon-coupled emission (SPCE) platform. To this end, silver-coated carbon nanotubes were used as spacer and cavity materials on SPCE substrates to obtain up to 100-fold fluorescence enhancements. The presence of silver on the carbon nanotubes helped to overcome fluorescence quenching arising due to π–π interactions between the carbon nanotube and rhodamine 6G. The competing adsorption of dopamine versus rhodamine 6G on graphene oxide was utilized to develop this sensing platform.