Garlic capped silver nanoparticles for rapid detection of cholesterol

A fluorescent biosensor based on garlic (Allium sativum L.) capped Ag nanoparticles (G-Ag NPs) has been synthesized for cholesterol detection. Pristine Ag NPs and G-Ag NPs were synthesized through the chemical reduction process. The effect of different capping agents such as 3-aminopropyltriethoxysilane (APTS), glutathione, 8-hydroxyquinoline, garlic/APTS, garlic/glutathione, and garlic/8-hydroxyquinoline on Ag NPs was evaluated. These NPs were characterized using Fourier transform infrared (FTIR), energy-dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), X-Ray diffraction (XRD), UV-visible spectra, and Zeta potential. The HRTEM micrographs illustrated that Ag NPs with particles size ranging from 2.98 to 14.34 nm were aggregated. G-Ag NPs images showed uniformly distributed spherical particles with particles size from 4.52 to 12.8 nm. The reduction in the plasmonic bands of Ag NPs and G-Ag NPs occurred by 96.4% and 11.7%, respectively after 12 months. The developed sensor for cholesterol based on the fluorescence enhancement had a linear response in a concentration range of 0.4-5.17 mM with a sensitivity of 4.36 Mm^-1 and a limit of detection of 0.186 mM. The high selectivity toward cholesterol in presence of different interferes such as glucose, cysteine, glycine, urea, sucrose, nickel, and copper, and their mixture was evaluated. The applicability of this developed sensor for real serum samples was detected with a recovery percentage from 99.1 to 101.3%. Repeatability and reproducibility experiments displayed relative standard deviations (RSD) of 0.88% and 0.62%, respectively.