Development of a Graphite Based Molecularly Imprinted Polymer Electrode for the Detection of Thymoquinone in Black Cumin: A Machine Learning-Assisted Approach

Abstract

Thymoquinone (TQ), a key bioactive compound in black cumin (Nigella sativa), is renowned for its therapeutic benefits, including anti-arthritic and immune-enhancing properties. Despite its importance, efficient methods for the sensitive and selective detection of TQ in black cumin remain underexplored. This study introduces a thymoquinone-imprinted graphite-based (TQIP/G) electrode as an innovative and cost-effective solution for the qualitative and quantitative assessment of TQ. The study emphasizes the sensitive and selective detection of TQ using a TQ-imprinted polymer material. The surface morphology and spectrographic properties of both the TQ-imprinted polymer and a non-imprinted polymer were extensively analyzed. A three-electrode system was employed for electrochemical evaluations through differential pulse voltammetry (DPV) and cyclic voltammetry (CV), revealing outstanding analytical performance. The TQIP/G electrode demonstrated a broad linear detection range (0.5 µM–100 µM), high sensitivity (0.11 A/M), excellent selectivity (57.09%), and impressive repeatability (RSD 3.23%) and reproducibility (RSD 3.56%). The electrode also exhibited exceptional stability and achieved a low limit of detection (LOD) of 0.03 µM. Additionally, a convolutional neural network (CNN) model was employed to analyze DPV responses from real samples, providing excellent correlation with reference RP-HPLC data and achieving an average error rate within ±0.005%. This demonstrates the reliability of the TQIP/G electrode as an efficient and accurate alternative to costly and time-consuming HPLC methods for determining TQ. The proposed sensor is poised to revolutionize the quality control of black cumin and other agricultural products by combining precision, scalability, and affordability.

Keywords: Black cumin, imprinted polymer, reverse phase high-performance liquid chromatography, thymoquinone, voltammetry