Nanostructured Ox-MWCNT-PPy-Au electrochemical sensor for ultralow detection of retrorsine and evaluation of its cytotoxic effects on liver cells.

Abstract

This study presents the development of a novel retrorsine (RTS)-imprinted sensor utilizing oxidized multi-walled carbon nanotubes (Ox-MWCNTs), polypyrrole (PPy), and gold nanoparticles (AuNPs), employing square wave voltammetry for the sensitive and selective detection of RTS which causes oxidative-stress and DNA damage. The fabricated Ox-MWCNT-PPy-AuNP sensor demonstrated a surface-area of (0.218 cm²) is 4.25 times larger than a bare glassy carbon electrode, with a low charge transfer resistance (10.9 Ω), enhancing electron transfer kinetics. The sensor showed excellent sensitivity in detecting retrorsine, with a limit of detection of 0.035 nM in synthetic matrices and -0.030 nM in HepaRG cell culture medium. Toxicity assays in HepaRG cells revealed dose-dependent oxidative-stress, with glutathione levels decreasing from 23.08 ± 0.21 µmol/10⁹ to 21.21 ± 0.02 µmol/10⁹ at 35 µM retrorsine. Concurrently, GSSG levels increased from 1.32 ± 0.26 µmol/10⁹ to 2.22 ± 0.02 µmol/10⁹. DNA-damage assessed via comet assay, showed significant increases in tail-moment (2.53 µm) and tail-migration (16.13 µm). Oxidative DNA-damage, indicated by 8-OHdG levels, increased significantly from 0.29 ± 0.02 ng.mL^- (control) to 0.47 ± 0.07 ng.mL^- at 35 µM retrorsine. These findings demonstrate the sensor's effectiveness for retrorsine detection and its applicability in toxicological studies. The integration of nanomaterial engineering and molecular imprinting provides a highly sensitive, selective, and eco-friendly solution for monitoring toxic agents and assessing their biological impacts.