 Nanotechnology has shown promise for its applications in agriculture, including increasing the content of bioactive compounds in crops such as tomatoes. This research found that the foliar application of copper nanoparticles, CUNPs, at various concentrations resulted in higher levels of vitamin C, lycopene, and antioxidants in the fruits. Additionally, the CUNPs decreased the activity of certain enzymes involved in oxidative stress, suggesting that they may be useful in protecting plants from environmental stresses. This article was authored by L. C. Rubisila Lopez-Vargas, Hortensia Hortagortis, Gregorio Cadenas Pliego, and others.