Electrochemical activation and renewal of pyrrole nitrogen sites in porphyrin-based conjugated polymer for simultaneous determination of uric acid and adrenaline

Abstract In this work, 5,10,15,20-tetrakis(4-ethynylphenyl) porphyrin-based conjugated polymer (P-TP) functionalized reduced graphene oxide (rGO), a renewable electrochemical sensor (P-TP/rGO), has been fabricated for the simultaneous determination of adrenaline (AD) and uric acid (UA). Herein, P-TP as a large π-conjugated aromatic system could not only provide more appropriate recognition sites, but also increase the adsorption degree of phenol and aniline via π-π interaction. Additionally, the involvement of alkyne bond within P-TP network could help improve the electron transfer efficiency in P-TP/rGO sensor due to its electron-adsorbing effect. Most importantly, activation of pyrrole N in porphyrin center by electrochemical reduction produces more catalytic sites and leads to higher electrochemical performance. The electrochemical results show that increasing the content of activated pyrrole N leads to higher catalytic activity, which suggesting that the activated pyrrole N can be responsible for the oxidation of AD and UA. Thus, our designed electrochemical sensor exhibits a sensitive response to AD and UA, with detection limits of 4.56 and 3.01 nM, respectively. Specially, after hundreds of successive determinations, the P-TP/rGO sensor can be renewed by a simple electrochemical reduction and maintain the satisfying repeatability, and reproducibility. This work also provides a helpful insight into effective activation and continuous renewing of porphyrin-based conjugated polymer in electrochemical bioanalysis.