In-situ growth of hydrogen-bonded organic framework on conductive PEDOT:PSS polymer to realize conductivity-enhanced electrochemiluminescence for fabricating ultrasensitive biosensor

Abstract

Hydrogen-bonded organic frameworks (HOFs) have gradually received research interest in the electrochemiluminescence (ECL) realm for their high porosity, large surface area, low toxicity, and remarkable biocompatibility, whereas the poor electrical conductivity of HOFs limits electrochemical excitation of ECL luminophores to cause low utilization ratio of ECL luminophores. To circumvent the problem, we prepared a conductive HOF composite (H3TATB-HOF/PEDOT:PSS) by in-situ growth of H3TATB-HOF (H3TATB = 2,4,6-tris(4-carboxyphenyl)− 1,3,5-triazine) on highly conductive poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) polymer. Satisfactorily, the ECL intensity of H3TATB-HOF/PEDOT:PSS presented a respective 14.94-time, 4.71-time, and 2.82-time improvement than those of H3TATB monomers, H3TATB aggregates, and H3TATB-HOF, which was mainly attributed to the high-conductivity PEDOT:PSS that facilitated charge transport throughout the H3TATB-HOF/PEDOT:PSS framework, enabling more H3TATB to be excited electrochemically. Considering the H3TATB-HOF/PEDOT:PSS featuring superior ECL properties, an ultrasensitive ECL biosensor for microRNA-21 assay was designed by combining H3TATB-HOF/PEDOT:PSS as an ECL beacon with a 3D DNA walker amplification strategy, exhibiting broad linear range (100 aM to 1 nM) with a low detection limit (45.7 aM). Overall, this work demonstrates that the ECL performance of HOF-based ECL materials can be significantly improved by enhancing electrical conductivity, thus providing a new idea to explore high-efficiency ECL emitters for building high-sensitivity ECL biosensors.