Biogenic Selenium Nanoparticles in Biomedical Sciences: Properties, Current Trends, Novel Opportunities and Emerging Challenges in Theranostic Nanomedicine

Abstract

Selenium is an important dietary supplement and an essential trace element incorporated into selenoproteins with growth-modulating properties and cytotoxic mechanisms of action. However, different compounds of selenium usually possess a narrow nutritional or therapeutic window with a low degree of absorption and delicate safety margins, depending on the dose and the chemical form in which they are provided to the organism. Hence, selenium nanoparticles (SeNPs) are emerging as a novel therapeutic and diagnostic platform with decreased toxicity and the capacity to enhance the biological properties of Se-based compounds. Consistent with the exciting possibilities offered by nanotechnology in the diagnosis, treatment, and prevention of diseases, SeNPs are useful tools in current biomedical research with exceptional benefits as potential therapeutics, with enhanced bioavailability, improved targeting, and effectiveness against oxidative stress and inflammation-mediated disorders. In view of the need for developing eco-friendly, inexpensive, simple, and high-throughput biomedical agents that can also ally with theranostic purposes and exhibit negligible side effects, biogenic SeNPs are receiving special attention. The present manuscript aims to be a reference in its kind by providing the readership with a thorough and comprehensive review that emphasizes the current, yet expanding, possibilities offered by biogenic SeNPs in the biomedical field and the promise they hold among selenium-derived products to, eventually, elicit future developments. First, the present review recalls the physiological importance of selenium as an oligo-element and introduces the unique biological, physicochemical, optoelectronic, and catalytic properties of Se nanomaterials. Then, it addresses the significance of nanosizing on pharmacological activity (pharmacokinetics and pharmacodynamics) and cellular interactions of SeNPs. Importantly, it discusses in detail the role of biosynthesized SeNPs as innovative theranostic agents for personalized nanomedicine-based therapies. Finally, this review explores the role of biogenic SeNPs in the ongoing context of the SARS-CoV-2 pandemic and presents key prospects in translational nanomedicine.

Keywords: SeNPs; biomedical applications; biosynthesis; nanomedicine; pharmacokinetics; selenoproteins; theranostics.

Figure 1

Main advantages of nanoparticles in biomedicine. Explored nanoplatforms in the biomedical field might be organic, inorganic, or hybrid. Inorganic NPs might be of different compositions, such as core-shell quantum dots and passivated inorganic NPs by an organic/polymeric layer, and of various shapes, such as spheres and nanotubes. Liposomes, polymeric NPs, and biopolymer-based NPs are some examples of organic NPs.

Figure 2

Selenium toxicity in humans and animals: cytotoxicity, genotoxicity, and epidemiology.

Figure 3

Main biomedical properties and applications of SeNPs.

Figure 4

Structure of SeNPs@GM1/TMP and their protective activity against t-BOOH induced neuron cell death. Reproduced with permission from Ref. [264]. 2019, the Royal Society of Chemistry.

Figure 5

The mechanism of ROS generation mediated by SeNPs. Adapted with permission from Ref. [174]. 2021, The Royal Society of Chemistry.

Figure 6

Biomedical application of SeNPs against viral infections.

Figure 7

Schematic representation of the different manners through which NPs enter the human body and are internalized inside the cells.

Figure 8

Schematic representation of multifunctional NPs that may include an imaging component, a targeting element, and a therapeutic constituent.

Figure 9

Confocal laser scanning microscopy images of antibiofilm activity of biogenic SeNPs, produced using the aqueous extract of Murraya koenigii against Gram-positive (E. faecalis and S. mutans) and Gram-negative (S. sonnei and P. aeruginosa) bacteria. Reproduced with permission from Ref. [109]. 2019, Elsevier.

Figure 10

Anticancer effect of biogenic, spherical SeNPs, synthesized by a living culture of B. lichenisformis, against PC3 cells via a necroptosis pathway. Adapted with permission from Ref. [295] under the terms of the Creative Commons CC BY license. 2017, Springer Nature.

Figure 11

Measurements of (A) ROS generation and (C) MMP induced by various concentrations (10–40 µg·mL⁻¹) of SeNPs using flow cytometry; (B,D) microscopy illustration of ROS and MMP production, respectively. Reproduced with permission from Ref. [285]. 2020, Elsevier.

Figure 12

Stakeholders (academic researchers, clinicians and patients, industry, regulatory bodies) and the main challenges faced in the translation of nanomedicine.