Electrochemical aptasensors, based on Au NPs, designed for the specific detection of antibiotic and cortisol residues

Aptasensors are highly valuable tools for detecting antibiotic residues because they combine the specificity of aptamers—synthetic single-stranded DNA or RNA molecules that can bind tightly to target antibiotics—with the sensitivity of advanced sensor technologies. Antibiotic and cortisol residues in food products, water, and the environment pose significant risks to human health, such as promoting antimicrobial resistance and causing allergic or toxic effects [1, 2].

In this study, gold nanoparticles (Au NPs) were prepared in the laboratory, starting from a solution of trihydrated gold (III) chloride solution (HAuCl4•3H2O) with a molar concentration of 0.50 mM and from a solution of sodium citrate with a molar concentration of 0.17 M, following a method adapted from the literature [3]. The synthesis was carried at about 98 °C, while the mixture was vigorously magnetically stirred at 950 rpm. The resulting Au NPs, with average diameters varying between 20 and 30 nm, were further functionalized with aptamers in order to develop electrochemical aptasensors for the specific detection of antibiotic and cortisol residues. The functionality of the modified sensors was then confirmed using a variety of characterization and testing methods, such as Dynamic Light Scattering (DLS), Ultraviolet–Visible Spectroscopy (UV-VIS), Transmission Electron Microscopy (TEM), and Energy-Dispersive X-ray Analysis (EDX).

References:

1. Sylvester Chibueze Izah, Akmaral Nurmahanova, Matthew Chidozie Ogwu, Zhexenbek Toktarbay, Zoya Umirbayeva, Kurmanbay Ussen, Laura Koibasova, Saltanat Nazarbekova, Bekzat Tynybekov, Zhanhu Guo, Public health risks associated with antibiotic residues in poultry food products, Journal of Agriculture and Food Research, 21 ( 2025) 101815, https://doi.org/10.1016/j.jafr.2025.101815;
2. Constanze Stiefel, Florian Stintzing, Endocrine-active and endocrine-disrupting compounds in food – occurrence, formation and relevance, NFS Journal, 31 (2023) 57-92, https://doi.org/10.1016/j.nfs.2023.03.004;
3. Zhenzhu Wu, Jinglun Liang, Xiaohui Ji, Wensheng Yang, Preparation of uniform Au@SiO2 particles by direct silica coating on citrate-capped Au nanoparticles, Colloids and Surfaces A: Physicochem. Eng. Aspects 392 (2011) 220– 224, https://doi.org/10.1016/j.colsurfa.2011.09.059.