A signal-amplification electrochemiluminescence sensor based on layer-by-layer assembly of perylene diimide derivatives for dopamine detection at low potential.

Perylene diimide derivatives (PDIs) are suitable ECL luminophore candidates with low triggering potentials and strong ECL signals for fundamental studies and practical applications. However, PDIs tend to aggregate, which affects their optical properties and limits their application in bio-imaging and bio-sensing fields. In this study, an ECL sensor is fabricated based on the layer-by-layer (LBL) assembly of N, N-bis(phosphonomethyl)-3,4,9,10-perylene diimide (PMPDI) and ZrIV ions on the surface of a mesoporous indium tin oxide (ITO) substrate. When six layers of PMPDI are immobilized on ITO, the resulting PMPDI6/ITO electrode shows maximum ECL intensity with K2S2O8 as a co-reactant in the potential range 0 to -0.5 V vs. Ag/AgCl. LBL assembly decreases the aggregation and increases the loading of PMPDI on the mesoporous ITO substrate, which stabilizes and amplifies the ECL signals. The ECL method exhibits excellent sensitivity and selectivity with good stability and reproducibility, when used to detect dopamine (DA) under optimal experimental conditions.