Heterocyclic nitrogen-regulated perylene diimide for co-reactant-free self-enhanced electrochemical sensing of carcinoembryonic antigen.

Abstract

Perylene diimide derivatives (PDIs) have become ideal probe materials for optimizing the analytical performance of biosensors for their unique optoelectronic response, excellent chemical stability and precisely tunable molecular structures. Traditional PDIs detection systems rely on co-reactant (K2S2O8) for signal amplification, limiting their applicability in biocompatibility and operational simplicity. This study adopted a donor-π-acceptor (D-π-A) structure-oriented molecular design strategy to synthesize three functionalized PDIs bearing six-membered diazine heterocyclic groups (PZ-PDI, PD-PDI and PM-PDI). Electrochemical tests showed that all three compounds produced current responses in the absence of co-reactant, with PZ-PDI exhibiting the highest current response. Further mechanistic studies reveal that the PZ-PDI electrode reaction is centered on the pyrazine-perylene diimide and relies on multiple synergistic interactions between the nitrogen-containing heterocycle and the perylene core, achieving efficient and stable self-enhanced current signal output without co-reactants. A co-reactant-free electrochemical immunosensor was further constructed by using AuNPs/PZ-PDI as the signal probe for the detection of the tumor marker carcinoembryonic antigen (CEA). The performance evaluation results showed that the immunosensor had an extensive linear detection range (10 fg·mL- 1-50 ng·mL- 1), and a low detection limit (1.14 fg·mL- 1). For the detection of clinical serum samples, there is no significant difference between the immunosensor's detection results and the clinically established chemiluminescence method. This strategy offers a new insight into the early screening and dynamic monitoring of CEA.

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