SUPRAMOLECULAR AGGREGATION-DRIVEN COLORIMETRIC DETECTION OF TETRAHYDROCANNABINOL USING Β-CYCLODEXTRIN-FUNCTIONALIZED SILVER NANOPARTICLES

Abstract

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. 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 linear response in the 0–35 μM THC range with a calculated limit of detection (LOD) of 8.8 μM and a limit of quantification (LOQ) of 26.8 μM. 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. The synthesized nanoprobes were further characterized using FTIR and UV-Vis spectroscopy, corroborating successful surface modification and inclusion complexation.