In situ growth of metal-organic layer on ultrathin Ti3C2Tx MXene nanosheet boosting fast electron/ion transport for electrochemiluminescence enhancement

Ultrathin metal-organic layers (MOLs) have attracted substantial attention in fabricating highly efficient electrochemiluminescence (ECL) materials due to their porous structure, small diffusion blockage, and short electron/ion-diffusion pathway, yet MOLs suffer from the inherent poor electrical conductivity that astricted the electrochemical activation, resulting in the unsatisfactory utilization ratio of ECL emitters. Herein, to address this limitation, we in situ hybridized Zr-based ultrathin MOL (Zr-TCBPE-MOL, H4TCBPE = 1,1,2,2-tetra(4-carboxylbiphenyl) ethylene) with the highly conductive Ti3C2Tx MXene nanosheet to obtain a unique 2D-2D hybrid nanocomposite (Zr-TCBPE-MOL/MXene). Benefiting from the above-mentioned attractive virtues of ultrathin MOLs and the superior conductivity of Ti3C2Tx MXene nanosheet, the resulting Zr-TCBPE-MOL/MXene nanocomposite permitted fast electron/ion transport across the whole framework of Zr-TCBPE-MOL/MXene, which efficiently boosted the electrochemical activation of TCBPE luminophores and thus improved the utilization ratio of luminophores to realize a remarkable ECL emission. Gratifyingly, we found that the ECL signal of Zr-TCBPE-MOL/MXene nanocomposite was greatly enhanced by around 4.1 times in contrast to that of pure Zr-TCBPE-MOL. On basis of the prominent ECL performance of Zr-TCBPE-MOL/MXene nanocomposite, a novel "off-on" ECL biosensor was proposed to sensitively analyze microRNA-141, which possessed a wide response range (100 aM-1 nM) and a low detection limit of 16.2 aM. Overall, this work puts forward a rational strategy to construct high-performance ECL materials and sheds new light on developing sensitive ECL sensing platforms.