Multifunctional substrate of label-free electrochemical immunosensor for ultrasensitive detection of cytokeratins antigen 21-1

Abstract

Poly(thionine)-Au, a novel multifunctional substrate with excellent redox signal, enzyme-like activity, and easy antibody immobilisation, was synthesised using HAuCl4 as the oxidising agent and thionine as the monomer. The prepared poly(thionine)-Au composite exhibited an admirable electrochemical redox signal at −0.15 V and excellent H2O2 catalytic ability. In addition, gold nanoparticles in this composite were found to directly immobilise antibodies and further improve conductivity. In addition, a label-free electrochemical immunosensor was developed using poly(thionine)-Au as the sensing substrate for ultrasensitive detection of cytokeratin antigen 21-1 (CYFRA 21-1), an immunoassay found in human serum. The prepared immunosensor showed a wide liner range from 100 ng mL−1 to 10 fg mL−1 and an ultralow detection limit of 4.6 fg mL−1 (the ratio of signal to noise (S/N) = 3). Additionally, this method was used to analyse human serum samples and yielded results consistency with those of ELISA, implying its potential application in clinical research. The poly(thionine)-Au composite can be easily extended to other polymer-based nanocomposites, which is significant for other electrochemical immunoassays.

Molecularly Imprinted Poly(thionine)-Based Electrochemical Sensing Platform for Fast and Selective Ultratrace Determination of Patulin

“…It could be obviously seen that in the synthesized nanomaterial, PtNPs were homogeneously distributed on the surface of the NGE, leading to more roughness and wrinkles, which greatly improved the electroactive surface (Figure B). After conjunction with MIP through electropolymerization, the thionine-PtNP-NGE was covered by a dense membrane with flexural nanostrips (Figure C), proving the successful synthesis of the poly­(thionine) (MIP) film through the –NH– bridge . The structure of the NGE, thionine-PtNP-NGE and MIP/thionine-PtNP-NGE were also characterized by SEM (Figure S1, Supporting Information, SI).…”

Nano-modified screen-printed electrode-based electrochemical immunosensors for oral cancer biomarker detection in undiluted human serum and saliva samples

“…19 Wang et al (2017) used a novel nanocomposite of multifunctional poly(thionine)-Au and found a wide detection limit of 4.6 fg mL −1 . 20 Pachauri et al (2018) reported cerium oxide nano-cubes (ncCeO 2 ) with a reduced graphene oxide (RGO)-nanocomposite and found a detection limit of 0.625 pg mL −1 . 21 One newly reported novel biomarker, TP-53, is also targeted for OC detection.…”

A probe-free electrochemical immunosensor for methyl jasmonate based on a Cu-MOF–carboxylated graphene oxide platform

“…This kind of sensor usually requires redox probes in the electrolyte solutions to generate amperometric signal that is proportional to the formed antigen/antibody complexes. 10 However, one of the main disadvantages of this method is time consuming and labor intensive. 11 Recently, redox probe-free platforms have been developed for immunosensors.…”