An electrochemical molecularly imprinted sensor based on dual polysaccharide-functionalized conducting polymer hydrogel for ultrasensitive detection of gibberellin.

Gibberellin A3 (GA3) is a pivotal phytohormone that modulates diverse aspects of plant growth, and is extensively applied in agricultural practices. It may harm animal physiology and pose potential carcinogenic risks, raising human health concerns. Developing a reliable GA3 detection method is critical for safeguarding public health and ensuring food safety. However, existing methods still lack sufficient rapid and sensitive detection capabilities. In this study, an electrochemical sensor was developed based on a molecularly imprinted hydrogel, integrating the conductive properties of conducting polymer hydrogels with the selective recognition capabilities of molecularly imprinted polymers. The conductive composite (CDs/PANI) was fabricated using carbon dots (CDs) and polyaniline (PANI) as precursors via electrochemical chronopotentiometry, which significantly improved the sensor's conductivity and electroactive surface area. Meanwhile, a three-dimensional hydrogel matrix was constructed from chitosan and sodium alginate using glutaraldehyde as a crosslinking agent. Based on this architecture, a molecularly imprinted electrochemical sensor was developed for the ultrasensitive and specific detection of GA3 in soil. The maximum relative standard deviation (RSD) of the measured GA3 values in spiked samples was 4.6%, with the consistency between electrochemical impedance spectroscopy (EIS) and chronocoulometry (CC) ranging from 94.1% to 106.2%. Target analyte was quantitatively analyzed by EIS and CC with a linear response range of 10-15 to 10-7 M. The detection limits were 0.334 fM (EIS) and 0.315 fM (CC), respectively. By integrating molecular imprinting technology with a conductive hydrogel matrix, the proposed sensor demonstrates high selectivity, excellent sensitivity, and robust anti-interference performance in biologically relevant matrices.