A facile ratiometric electrochemical sensing platform with in-situ electropolymerized thionine on effective sensing of 5-hydroxytryptamine

The ratiometric electrochemical sensors have been highly explored to minimize system errors and environmental interference. However, it is extremely desirable on the development of an effective ratiometric electrochemical sensor in a facile approach without the complicated assembly process. In this work, an effective internal reference probe was coupled based on the polymerized thionine (pTh) via a one-step electrodeposition method. The ratiometric electrochemical sensing platform was applied for 5-hydroxytryptamine (5-HT) detection, where the internal reference probe, Th, presented the robust redox signal and can be clearly distinguished from the oxidation signal of 5-HT. The proposed pTh modified GCE presented the outstanding electrochemical performance on sensing 5-HT in a wide concentration range with a detection limit of 8.4 nΜ. Further, the fabricated sensor was efficiently employed for the detection of 5-HT in various human serum samples and the obtained results were consistent with the reported range in serum samples. This work offers the great possibility on the fabrication of efficient ratiometric sensors in a facile approach and presents great application prospects in clinical diagnosis.