Biomass-derived nitrogen-doped carbon quantum dot-embedded electrospun PVA/PVP seed coatings for the electrochemical monitoring of germination and stress responses in Vigna mungo.

In this study, a nanoengineered seed coating formulation composed of polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP) and biomass-derived carbon quantum dots synthesized from orange peels (OP-CQDs) was developed. Nitrogen-doped fluorescent OP-CQDs were prepared via a green microwave-assisted route and systematically characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) and Raman spectroscopies, high-resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FESEM), and zeta potential analysis. The OP-CQDs exhibited a narrow size distribution with an average diameter of 4.63 nm, excellent aqueous dispersibility, high photostability and a fluorescence quantum yield of 52.46%. The OP-CQDs were incorporated into electrospun PVA/PVP membranes to form functional seed coatings, and their structure-property relationships were correlated with germination performance, stress response and electrochemical behaviour during nutrient uptake in Vigna mungo. Seed viability and early seedling development were evaluated using conventional growth metrics and electrochemical techniques, including potentiostatic electrochemical impedance spectroscopy (PEIS) and cyclic voltammetry (CV). Among the formulations investigated, the optimized coating, S5 (40 wt% OP-CQDs), exhibited an enhanced germination rate, seedling vigor and biomass accumulation. Comprehensive physicochemical analysis of the OP-CQD-embedded electrospun membranes was performed using XRD, FESEM, FT-IR spectroscopy, and UV light observation. Electrochemical studies revealed that the OP-CQD concentration governed charge transfer resistance and ion diffusion behaviour, thereby modulating nutrient uptake kinetics and stress responses during germination. This work demonstrates a multifunctional, biomass-derived CQD-based electrospun coating that integrates controlled nutrient delivery with real-time electrochemical sensing, offering a sustainable material platform for next-generation smart agricultural interfaces.