Abstract
Selenium nanoparticles (SeNPs) are successfully synthesized through microwave heating by using Theobroma cacao L. bean shell extract as a stabilizing and capping agent. Response surface methodology is used to obtain optimal synthesis conditions. The effect of microwave power, irradiation time and amount of Na2SeO3 are evaluated on crystalline size by X-ray Diffraction (XRD) and Z-potential by Dynamic Light Scattering (DLS) using a central composite design (CCD). Optimal synthesis conditions are determined as 15.6 min, 788.6 W and 0.14 g of sodium selenite using 50 mL of Theobroma cacao L. bean shell extract. The successful biosynthesis of SeNPs is confirmed by UV-visible and Fourier Transformed Infrared (FTIR) spectroscopic analyses. The XRD pattern and Raman spectra show the presence of trigonal and amorphous synthesized SeNPs. Spherical SeNPs are observed by Transmission Electron Microscopy (TEM) with a particle size of 1–3 nm in diameter, at least one order of magnitude lower than those previously reported. The obtained SeNPs can be stable up to 55 days at 4 °C. Additionally, the SeNPs show an excellent antioxidant performance by the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and ferric reducing antioxidant power (FRAP) methods, with potential application in different sectors, such as food, medical and pharmaceutical.
Highlights
Selenium is an essential element for the operation of multiple biological processes in humans, but their concentration threshold between functionality and toxicity is very narrow [1]
Hydroxyl groups may act as capping agents by the deposition of bioactive compounds on the selenium nanoparticles (SeNPs)’ surface [8] preventing them from aggregation and, adding antioxidant capacity
The SeNPs obtained showed experimental values of 41.5 ± 1.7 nm of diameter and −28.6 ± 5.3 mV for Z-Potential, which did not differ significantly (p > 0.05) from predicted values of 40.8 ± 5.4 nm and −27.1 ± 4.4 mV, respectively. These results showed the strong correlation between the predicted and experimental data, confirming that the models were reliable for the optimization of green SeNPs synthesis through microwave heating
Summary
Selenium is an essential element for the operation of multiple biological processes in humans, but their concentration threshold between functionality and toxicity is very narrow [1]. Selenium can be present in Nature showing different polymorphic structures, either crystalline or amorphous. The crystalline forms include three allotropes of monoclinic selenium (m-Se) containing rings of Se8 with different packing to give red monoclinic forms (α, β and γ). Black trigonal selenium (t-Se) is the most stable crystalline form at room temperature [2]. The most important non-crystalline forms of selenium are the red amorphous (a-Se), black amorphous and vitreous selenium [3]. Since the late 1990s, the application of nanotechnology in different fields has received extensive attention. Selenium nanoparticles (SeNPs) have been reported to exhibit excellent bioavailability, low toxicity and strong antioxidant and antibacterial activity [8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
