Caffeic and phenolic acids from ocimum gratissimum integrated with metal–organic frameworks for advanced sensor development

The increasing demand for low-cost, sensitive, and sustainable sensing technologies, has called for the exploration of bio-derived functional materials integrated with advanced nanostructures. This study investigated the extraction of caffeic and other phenolic acids from Ocimum gratissimum (scent leaf), and their integration into metal–organic frameworks (MOFs) for the development of high-performance electrochemical sensors. Phenolic acids were extracted using solvent-based techniques, and characterized through High-Performance Liquid Chromatography (HPLC), Fourier Transform Infrared Spectroscopy (FTIR), and UV–Visible spectroscopy, achieving purity levels exceeding 90%. Three MOF systems (UiO-66, HKUST-1, and MIL-101) were synthesized through green solvothermal, and mechanochemical methods and structurally validated using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface analysis, and electron microscopy (SEM/TEM). The resulting phenolic acid–MOF hybrids were immobilized on electrode substrates, and evaluated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The hybrid sensors demonstrated a 30–45% increase in sensitivity, enhanced electron transfer kinetics, and improved stability compared to conventional phenolic-based electrodes. Detection limits for heavy metals (Pb²? and Cd²?) and food spoilage biomarkers were significantly reduced, with reproducibility maintained below 5% relative standard deviation. The integration of indigenous plant derived molecules with MOFs provides a sustainable pathway for advanced sensor development, with applications in environmental monitoring, food safety, and biomedical diagnostics. This work contributes to green nanotechnology, promotes local resource utilization, and supports Sustainable Development Goals (SDGs 3, 9, and 12).

Uchechukwu Vincent Okpala is a Professor of Physics at Chukwuemeka Odumegwu Ojukwu University, Uli, Nigeria. He obtained his Ph.D. in Physics (Solar Energy) and has extensive academic and research experience spanning solid state physics, materials science, electronics, and renewable energy. He has held several leadership roles, including Head of Department and Director of research centers, and has supervised numerous undergraduate and postgraduate projects. Prof. Okpala has published over 50 scholarly articles in reputable journals and serves as an editor and reviewer for academic publications. He is a Fellow of the Materials Science and Technology Society of Nigeria and an active member of several professional bodies.