Biomolecule-mediated nanoparticle synthesis has recently gained the attention of researchers due to its ecofriendly and non-toxic nature. Metabolites from plant extracts represent a better alternative to chemical methods to fulfill the growing demand for non-hazardous nanoparticle synthesis routes. Selenium and its nanoparticles have an extensive range of applications. Thus, biofabrication of selenium nanoparticles can be potentially useful in various fields. This study reports a green approach to biosynthesize selenium nanoparticles (Se-np) using dried Vitis vinifera (raisin) extracts. The biosynthesized selenium nanoparticles were characterized using transmission electron microscope (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy and Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopic images revealed the spherical shape of biosynthesized selenium nanoparticles and a size range of 3-18 nm. Dynamic light scattering also confirmed the average particle size of 8.12 ± 2.5 nm with 0.212 PDI. The crystalline nature of selenium nanoparticles was confirmed by the X-ray diffraction study. Moreover, as inferred from the FTIR spectrum, the presence of highly stable lignin biopolymer on the surface of selenium nanoballs suggests a possible role as capping agent.

Quercetin is a promising chemopreventive agent against cancer that inhibits tumor progression by inducing cell cycle arrest and promoting apoptotic cell death. Recently, the Wnt/β-catenin signaling pathway has been implicated in mammary tumorigenesis, where its abnormal activation is associated with the development of breast cancer. Thus, the objective of this study was to examine the biological activities of quercetin against mammary cancer cells, and to determine whether quercetin could regulate the Wnt/β-catenin signaling pathway. Quercetin showed dose-dependent inhibition of cell growth and induced apoptosis in 4T1 cells. Treatment of 20 µM quercetin suppressed ~50% of basal TopFlash luciferase activity. Moreover, the inhibitory effect of quercetin on the Wnt/β-catenin signaling pathway was confirmed by the reduced stabilization of the β-catenin protein. Among various antagonists screened for the Wnt/β-catenin signaling pathway, the expression of DKK1, 2 and 3 was induced after treatment with 20 µM of quercetin. Stimulation with recombinant DKK1 protein, showed suppressive cell growth of mammary cancer cells instead of quercetin. When 4T1 cells were treated with recombinant Wnt3a or LiCl along with quercetin, both stimulators for the Wnt/β-catenin signaling pathway were able to restore the suppressed cell viability by quercetin. Thus, our data suggest that quercetin exerts its anticancer activity through the downregulation of Wnt/β-catenin signaling activity. These results indicate for the first time that quercetin decreases cell viability and induces apoptosis in murine mammary cancer cells, which is possibly mediated by DKK-dependent inhibition of the Wnt/β-catenin signaling pathway. In conclusion, our findings suggest that quercetin has great potential value as chemotherapeutic agent for cancer treatment, especially in breast cancer controlled by Wnt/β-catenin signaling activity.

Our data suggest that MPEG-PLA-Qu nanoparticle can have a promising clinical potential for the treatment of breast cancer.