Fabrication of a polypyrrole-functionalized biogenic Mg(OH)2@MgO immunosensor, synthesized using Graptopetalum paraguayense leaf extract, for selective and efficient impedimetric detection of cholecalciferol (Vit-D3)†

Vitamin D has gained significant global attention for its potential to prevent chronic conditions such as cancer, Parkinson's, Alzheimer's, cardiovascular disease, and osteoporosis. However, there are still no convenient techniques for interpreting the concentration Vit-D₃ in humans for diagnosis and monitoring. In this study, a B–Mg(OH)₂/MgO/PPy nanocomposite was hydrothermally synthesized using fresh leaves of the traditional Chinese medicinal plant Graptopetalum paraguyense, and confirmed by optoelectronic techniques. It is possible that this sustainable, chip-based, cost-efficient and cost-sensitive impedance biosensor can be used to quantify vitamin D3 concentration in humans. In this process, a sustainable BSA/Ab Vit-D/B–Mg(OH)₂@MgO/PPy NCs/ITO biosensor was fabricated that has neutral linker properties for immobilization of the antibody of Vit-D. The electrochemical performance of the biosensor was studied by EIS with linearity in the ΔR_ct value over the wide range of 1–200 nM with a limit of detection (LoD) of (0.026 nM) and sensitivity of 1.40 Ω nM⁻¹ cm⁻². This ultrasensitive biosensor has excellent stability, reusability, a fast response time, and precise selectivity. Further validation of fabricated biosensors of Vit-D₃ was undertaken in real serum and spiked serum samples for a diagnostic approach. Therefore, the proposed sustainable, cost-effective, and sensitive biosensor shows promise for point-of-care diagnosis of vitamin-D-related diseases.