Functional nanostructures in analytical chemistry: new insights into the optical and electrochemical sensing of animal hormones in food, environmental and biological samples

Hormones, which are complex biomolecules, play a vital role in various biochemical pathways and the growth of animals. Hormones, both natural and synthetic, are widely used in agriculture and dairy farms; however, they pose serious health risks. They are responsible for major changes in living organisms related to reproductive health, stress control, pigmentation, glucose metabolism, etc. The quantity of hormones in living bodies is quite low, and thus efficient techniques for their detection are required. However, conventional analytical strategies for the detection of animal hormones exhibit some limitations, such as being time-consuming, expensive, frequently inaccurate, and challenging to use. In this review, we present a detailed classification of animal hormones and a brief description of different sample preparations from food matrices for hormone assays. As summarized in this review, nanostructured material-based optical (colorimetric and fluorescence) and electrochemical sensors have become promising miniaturized analytical tools for the selective and sensitive detection of animal hormones in food samples. Furthermore, we provide an overview on the integration of various nanomaterials (carbon nanostructures, metal nanoclusters, metal nanoparticles, metal-organic frameworks, and quantum dots) with UV-visible, fluorescence, and electrochemical analytical methods for the identification of various animal hormones in food samples with minimized sample volume and preparation. Nanomaterial integrated analytical techniques for the detection of animal hormones.