Posted by This study presents a novel, facile approach for the colorimetric detection of tetrahydrocannabinol (THC) using β-cyclodextrin functionalized silver nanoparticles (β-CD-AgNPs), offering a rapid and label-free sensing method with visual interpretability. Tetrahydrocannabinol (THC) is the principal psychoactive compound in cannabis, playing a crucial role in its therapeutic use as well as raising concerns about its potential for abuse. β-CD-AgNPs were synthesized via a green chemical reduction method, employing silver nitrate as the precursor and β-cyclodextrin as a dual-role stabilizing and functionalizing agent. Upon interaction with THC, a noticeable color shift from yellow to blue-green was observed, corresponding to nanoparticle aggregation and a red shift in localized surface plasmon resonance (LSPR). The system exhibited a concentration-dependent optical response across the 0–35 μM THC range, with a statistically linear region between 10 and 35 μM. The calculated limit of detection (LOD) and limit of quantification (LOQ) were 0.022 μM and 0.066 μM, respectively. Dynamic Light Scattering (DLS) and Zeta Potential (ZP) analyses were employed to evidence size augmentation (from 53.7 to 3143.6 nm) and decreasing colloidal stability (from −37.4 to −5.1 mV), respectively, with increasing THC concentrations. These physicochemical transformations validated THC-induced nanoparticle aggregation as the key sensing mechanism. Specificity studies using potential interferents such as CBN, CBD, limonene, Fe(III), and quercetin confirmed the probe’s high selectivity for THC, while EDTA addition helped suppress ionic interferences. Notably, the method was extended to paper-based sensing using filter strips, enhancing field applicability.
Junaid Iqbal, Maria Kanwal, Abu Bakar Siddique, Khaled Fahmy Fawy, Muhammad Sher, Umar Nishan, Muhammad Fayyaz ur Rehman, Muhammad Azhar Abbas, Arshad Ali, Azhar Abbas (2025) β-Cyclodextrin-functionalized silver nanoparticles as a visual probe for selective tetrahydrocannabinol detection via host–guest induced plasmonic shifts. Microchemical Journal 219, 116177. https://doi.org/10.1016/j.microc.2025.116177