Selenium Nanoparticle Applications

Introduction

Selenium is an essential trace element, vital for both human and livestock nutrition. It is a necessary dietary constituent of at least 25 human selenoproteins and enzymes containing selenocysteine. Due to its many health benefits selenium is a common additive to animal feeds and nutritional products. Additionally, as selenium is a semi-conductor and photoelectrically active it has more advanced applications such as xerography and solar cell assembly. Selenium rarely occurs in its elemental state and has typically been observed in its organic (selenomethionine, selenocysteine) or inorganic (selenate, selenide, selenite) forms.

The development of uniform, monodisperse, nanometre sized selenium particles has gained commercial interest as such nanoparticles often display interesting electrical, optical, magnetic, and chemical properties in comparison to their bulk counterpart materials. The application of selenium nanoparticles (SeNPs) is of particular interest as it has been shown to enhance selenium’s biological and photoelectric properties. Furthermore, SeNPs are biocompatible and non-toxic, and exhibit low cytotoxicity compared to the counterparts, selenite (SeO32-) and selenate (SeO42).

Fig. A. Photographic images of six size-distinguishable selenium colloids. From left to right, the images represent mean particle diameters of 20.0±6.1,70.9±9.1, 101.6±9.8, 146.1±23, 182.8±33.2, and 240.4±32.2 nm.

Fig. B. TEM image of uniform, monodisperse chemically synthesised selenium nanoparticles

Application Area 1: Increased bioavailability of Human Food/Animal Feed supplements

Nanosized particles may offer nutritional benefits such as enhanced absorption, bioavailability, antimicrobial activity, and excretion of the nanomaterials. The supplementation of animal nutrition products with SeNPs has shown highly promising outcomes when added to monogastric, ruminant and aquatic feeds (see Fig. 1. for applications of SeNPS in animal feeds). Nanoparticle delivery of minerals has been shown to be effective in improving feed conversion ratio, promote growth and development of muscle cells, improve the gut microbial environment, treat common parasitic disease such as coccidiosis and reduce mortality in poultry. Traditionally selenium is added to animal feeds in either its inorganic (selenite) or organic (seleno-methionine) form.

However, the use of selenium in its nanoparticle form in animal feed may be an attractive alternative as it does not need to be metabolised before being incorporated into selenoproteins and is thus more bioavailable than inorganic selenium. At present, there is a void of human SeNP supplementation trials and commercial products, however this is an area of highly promising research.

Fig. 1. Applications of SeNPs in animal feeds