Herein, a ternary electrochemiluminescence (ECL) sensing platform with high luminous efficiency was established for ultrasensitive bioanalysis of the microRNA-21 (miR-21) from
cancer cell based on
N-(aminobutyl)-N-(ethylisoluminol) (
ABEI) as ECL emitter, dissolved O2 as coreactant, and
silver bismuth oxide nanocrystals (Ag3BiO3 NCs) as coreaction accelerator. Specifically, a novel coreaction accelerator Ag3BiO3 NCs was introduced into the
ABEI/dissolved O2 system to form an ECL ternary system, which could promote the reduction of dissolved O2 to generate great deal of
superoxide anion radical (O2•-), reacting with the
ABEI to dramatically enhance the ECL performance. Simultaneously, a small amount of target miR-21 could trigger a one-step
DNA self-assembly to form the
DNA nanonet for embedding abundance
ABEI with the assistance of
doxorubicin hydrochloride (Dox), realizing the high-intense ECL response. Furthermore, owing to the thin-layer and porous structure, the obtained
DNA nanonet could shorten the electron-transfer path of the ternary ECL system to reduce the energy loss, further improving the sensitivity of the sensing platform. As expected, the developed ECL sensing platform of miR-21 detection manifested prominent sensitivity with a low detection limit of 7.1 aM in the concentration of miR-21 range from 10 aM to 100 pM. Satisfactorily, the proposed sensing platform was triumphantly applied to detect
miRNA in
tumor cell lysates. Consequently, the designed strategy broadened the application of
ABEI in
biological analysis and hewed out a new path to establish the ECL ternary system with high luminous efficiency.