Walnut leaf extract-based green synthesis of selenium nanoparticles via microwave irradiation and their characteristics assessment

Kosar Sheikhlou,Yahya Najian,Sima Sabouri,Somaiyeh Allahyari,Hoda Jafarizadeh-Malmiri

doi:10.1515/opag-2020-0024

Kosar Sheikhlou, Yahya Najian + Show 3 more

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https://doi.org/10.1515/opag-2020-0024

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Abstract

Abstract Selenium nanoparticles (Se NPs) have predominant characteristics compared to that in their bulk usage due to their high surface-to-volume ratio. The walnut (Juglans regia L.) leaf extract containing different bioactive compounds that act as reductant and stabilizing agents has been used for the green synthesis of the Se NPs. Influences of two synthetic variables, namely, the amount of selenium salt solution ranging from 15 to 25 mL and the amount of walnut leaf extract ranging from 1 to 5 mL, on broad emission peak (λ max) and absorbance of colloidal solutions having Se NPs were evaluated via the response surface methodology. Obtained results indicated that using microwave radiation (800 W for 4 min) and 5 mL of walnut leaf extract and 15 mL of selenium salt solution, Se NPs with λ max, absorbance, particle size, polydispersity index, and zeta potential values of 375 nm, 3.65% absorbance unit (a.u.), 208 nm, 0.206, and −24.7 mV were synthesized, which had high bactericidal activity toward Escherichia coli and Staphylococcus aureus. The transmission electron microscopy analysis also indicated that spherical and monodispersed Se NPs with a mean particle size of 150 nm were formed using the walnut leaf extract.

Highlights

Selenium, a nonmetal trace element, has gained more attention in pharmaceuticals and medicine areas due to its unique properties such as lower toxicity, higher antioxidant activity, anticarcinogenic, muscle functioning, antimicrobial activities, and progressive effect on thyroid metabolism (Fardsadegh et al 2019)
The walnut (Juglans regia L.) leaf extract containing different bioactive compounds that act as reductant and stabilizing agents has been used for the green synthesis of the selenium nanoparticles (Se NPs)
The hydroxyl groups play a main role in the reduction of selenium ions to their elements. This functional group could be found in the structure of polyphenol compounds and flavonoids, which were detected in the walnut extract by Eshghi et al (2018). They found that proteins and enzymes existed in the walnut leaf extract by observing the amide group (1637.48 cm−1), as shown in Figure 1, that was related to these biomolecules

Summary

Introduction

A nonmetal trace element, has gained more attention in pharmaceuticals and medicine areas due to its unique properties such as lower toxicity, higher antioxidant activity, anticarcinogenic, muscle functioning, antimicrobial activities, and progressive effect on thyroid metabolism (Fardsadegh et al 2019). Selenium in nanoscale has predominant characteristics compared to that in its bulk usage. These distinctive properties are related to the high surface-tovolume ratio and surface energy of the selenium nanoparticles (Se NPs) (Prasad et al 2013). Natural existed bioreductants and stabilizers in the plans, such as carbohydrates, alkaloids, proteins and enzymes, phenolic acids, flavonoids and polyphenols have key roles in the synthesis of NPs (Mohammadlou et al 2016; Eshghi et al 2018). Compared to the physicochemical synthesis methods to fabricate inorganic NPs, green processes are time consuming, which can be fixed by fast heating methods such as hydrothermal and microwave radiation (Torabfam and Jafarizadeh-Malmiri 2017; Ghanbari et al 2018). Moving of the metal NPs is accelerated in the microwave electric field because they carry electrical charges (Eskandari-Nojedehi et al 2016)

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