Construction, characterization, and bioactive evaluation of nano-selenium stabilized by green tea nano-aggregates

Natural bioactive compounds have been widely used as templets in the stabilization and functional improvement of nano-selenium (SeNPs) in recent years. Herein, green tea nano-aggregates, bioactive colloidal particles spontaneously assembled by tea polyphenols, proteins, and carbohydrates in tea infusions, were introduced as a novel templet for the green synthesis of SeNPs via the ascorbic acid-sodium selenite (Na2SeO3) redox reaction. Primarily, hydrodynamic diameter and Zeta potential of SeNPs produced under different conditions were analyzed by dynamic light scattering and laser Doppler velocimetry. Accordingly, the ratio between ascorbic acid and Na2SeO3 of 8:1 (mmol: mmol) with 500 mg/L of green tea nano-aggregates at 40 °C for 1 h was controlled for SeNPs preparation. On this basis, red, zero-valent, amorphous and spherical SeNPs of 50 nm in diameter with high electrostatic stability (−41.5 mV) were successfully constructed and characterized via transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. SeNPs exhibited stronger inhibition on the proliferation of carcinoma cells HCT 116 and MDA-MB-231 compared with Na2SeO3. This work provides an innovative strategy for the green synthesis of SeNPs and advances our basic knowledge about the interactions between SeNPs and templets.