Persulfate-mediated dual-emitting conjugated polymers for electrochemiluminescence ratio analysis of SARS-CoV-2 RdRp gene

Polymers have attracted attention as luminophores due to their excellent electrochemiluminescence (ECL) properties. However, the current research and application of polymers mainly focus on anode emission, and ECL efficiency is not high enough, thus showing a limited application. This work exploited the persulfate-mediated dual-emission characteristics of poly[2,5-dioctyl-1,4-phenylene] polymer nanoparticles (PDP PNPs). The two ECL emissions were collected synchronously at − 2.0 V and + 1.0 V with persulfate (S2O82-) as cathodic coreactant and 3-(dibutylamino) propylamine (TDBA) as anodic coreactant, respectively. Interestingly, S2O82- can simultaneously mediate the double emissions, significantly enhancing both cathode emission and anode emission. The dual-emission mechanism was explored carefully and enhancement mechanism of cathodic coreactant S2O82- to anodic emission was hypothesized to be attributed to SO4∙− radicals, which was produced from S2O82- during cathodic potential scanning and oxidized PDP PNPs to generate more cation radical, thus enhancing anodic emission of PDP PNPs. Moreover, the black hole quencher-2 (BHQ2) was exploited as dual-function moderator to quench dual emissions of PDP PNPs synchronously. PDP PNPs coupled with BHQ2 to build ECL ratiometric system for detecting SARS-CoV-2 RdRp gene and its limit of detection was 25.1 aM. Persulfate-mediated double emissions provided a new way to improve the efficiency of ECL emission from polymers and expand their application. The clever integration of dual-emitting PDP PNPs and dual-regulating BHQ2 created a promising single-luminophore-based ratiometric ECL platform, developed an attractive ECL method for detecting SARS-CoV-2 RdRp gene.