Multiple lines of evidence show that cancer stem cells inside solid tumors start and maintain tumor growth. These cells stay dormant even after anti-cancer drugs are used to treat the tumor. Different flavonoids might help protect against cancer by messing up pathways that are linked to cancer stem cells. Flavonoids like quercetin are used in many medicine ways. By acting as an antioxidant and an anti-inflammatory, quercetin can stop the growth of cancer stem cells. It can also control many molecular processes that are linked to the growth of cancer. As a chemical plan, it can be used in combinatorial synthesis. It is possible to find molecular targets. Figuring out exactly which molecules quercetin targets could help scientists make more precise molecules that only go after those shared spots. Synergistic effect: Now that we know more about how quercetin works at the molecular level, we can look into how it might work with other substances to help avoid cancer. The goal of this study was to make nanoparticles that contain quercetin so that they can be used in specific drug delivery systems. Then, several cancer stem cell types were used to test these nanoparticles.