Metal ion-mediated potential-resolved ratiometric electrochemiluminescence bioassay for efficient determination of miR-133a in early diagnosis of acute myocardial infarction.

Potential-resolved electrochemiluminescence (PRECL)-based strategies utilizing novel nanoluminophores have become a re-search hotspot in analytical sciences in virtue of the superior versatility, specificity and sensitivity they offer to bioassays. In this work, a novel PRECL nanoluminophore graphitic carbon nitrides (g-C₃N₄) functionalized by N-(aminobutyl)-N-(ethylisoluminol) (ABEI) (g-C₃N₄/ABEI) was developed, exhibiting two potential-resolved ECL emissions in the presence of H₂O₂/K₂S₂O₈ as coreactants with the peak potentials at +1.2 and -1.6 V, respectively. It was found that Hg²⁺ could simultane-ously decrease the ABEI electrochemiluminescence (ECL) intensity while increasing the intensity of g-C₃N₄ on the contrary. Using Hg²⁺ as the ECL signal moderator based on specific interactions between Hg²⁺ and thymine-thymine pairs, conjoined with the synthesized g-C₃N₄/ABEI/Hg²⁺ nanohybrids with outstanding PRECL properties as the sensing interface, a label-free and all-in-one ratiometric ECL bioassay combined with rolling circle amplification (RCA) strategy was designed for the detection of miR-133a as a biomarker in early diagnosis of acute myocardial infarction (AMI). The proposed bioassay provided a quantita-tive readout proportional to the target miR-133a concentrations in the range of 0.1 fM to 1.0 pM with a detection limit of 48.0 aM. Owing to its inherent merits for effective amplification of the ECL signals ratio and a simple one-step assembly proce-dure, the proposed bioassay demonstrated excellent analytical performance with remarkable sensitivity, specificity and low measurement deviations, manifesting its potential application in early AMI diagnosis.