Abstract
Polythionine (PTH) is an electroactive compound known for its excellent electron transfer capacity. It has stable and redox centers in its structure, and it can also be generated by electropolymerization of thionine (TH). Due to its properties, it has been used in a large number of applications, including the construction of electrochemical biosensors. In this work, PTH is explored for its ability to generate electrons, which allows it to act as an electrochemical probe in a biosensor that detects CA 19-9 on two different substrates, carbon and gold, using differential pulse voltammetry (DPV) as a reading technique in phosphate buffer (PhB). The analytical features of the resulting electrodes are given, showing linear ranges from 0.010 to 10 U/mL. The Raman spectra of PTH films on gold (substrates or nanostars) and carbon (substrates) are also presented and discussed as a potential use for SERS readings as complementary information to electrochemical data.
Highlights
Received: 29 December 2021The use of conventional electrodes has evolved through several designs and one of the most used is based on chemically modified electrodes (CMEs)
It has been proposed that the tion potential should not be less than +0.9 V, because the potential of the electrode should oxidation potential should not be less than +0.9 V, because the potential of the electrode be greater than the potential in which the oxidation of TH is occurring [14]
A new molecularly imprinted polymers (MIPs) material for cancer antigen 19-9 (CA 19-9) was presented for electrochemical reading of this cancer biomarker
Summary
The use of conventional electrodes has evolved through several designs and one of the most used is based on chemically modified electrodes (CMEs). PTH-modified electrodes have been prepared in a simple way by cyclic voltammetry (CV) having a solution of TH under a potential sweep in the range from −0.4 to +0.4 V [10]; the specific potential range of interest depends on the electrical features of the receptor substrate. They may be obtained by chronoamperometry, in which a constant oxidation potential is applied for a given time [11]. Ferreira et al conducted electrochemical characterization studies of PTH films produced by different scanning speeds and variations in the number of potential cycles They concluded that the electroactivity and stability of the resulting PTH are pH-dependent. The resulting structure of PTH was evaluated using Raman spectroscopy, along with a control material prepared in the absence of CA 19-9 and gold nanostars modified with TH
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