Mass-amplifying electrochemiluminescence film (MAEF) for visual detection of dopamine in aqueous media
Bright and metal-free mass-amplifying electrochemiluminescence film (MAEF) performed in aqueous media were reported for the first time. Systematic study demonstrates that film substrates play a remarkable influence on their electrochemiluminescence (ECL) performance. Gold substrates promote ECL reactions and subsequent radiative decay process simultaneously, affording an unconventional ECL enhancement by 507-fold. Such gold-enhanced MAEF is opposite to ECL systems reported, in which use of gold electrodes normally results in decreased ECL intensity due to passivation of gold surface by oxide formation. More importantly, ECL intensity of MAEF is linearly amplified through facilely regulating luminogen loading. Morphological analysis reveals that the film consists of grass-like nanowires with a diameter of 57 nm, which facilitates electrical communication among the luminogen, electrode, and supporting electrolyte, giving rise to the mass-amplifyig ECL. The bright ECL of the solid film in aqueous media can be readily observed by the naked eye, entirely different from the visible ECL systems reported, in which ruthenium complex disolved/dispersed in solutions is used as luminogens. The film is further utilized to detect dopamine (DA), an important biomolecule related to nervous diseases, in aqueous media with a low detection limit of 3.3×10-16 M. Furthermore, a facile method based on grayscale analysis of ECL images (GAEI) of the film is developed for visual and ultrasensitive DA detection in aqueous media.