Unveiling Green Synthesis and Biomedical Theranostic paradigms of Selenium Nanoparticles (SeNPs) - A state-of-the-art comprehensive update

The advancements in nanotechnology, pharmaceutical sciences, and healthcare are propelling the field of theranostics, which combines therapy and diagnostics, to new heights; emphasizing the emergence of selenium nanoparticles (SeNPs) as versatile theranostic agents. This comprehensive update offers a holistic perspective on recent developments in the synthesis and theranostic applications of SeNPs, underscoring their growing importance in nanotechnology and healthcare. SeNPs have shown significant potential in multiple domains, including antioxidant, anti-inflammatory, anticancer, antimicrobial, antidiabetic, wound healing, and cytoprotective therapies. The review highlights the adaptability and biocompatibility of SeNPs, which are crucial for advanced disease detection, monitoring, and personalized treatment. Special emphasis is placed on advancements in green synthesis techniques, underscoring their eco-friendly and cost-effective benefits in biosensing, diagnostics, imaging and therapeutic applications. Additionally, the appraisal scrutinizes the progressive trends in smart stimuli-responsive SeNPs, conferring their role in innovative solutions for disease management and diagnostics. Despite their promising therapeutic and prophylactic potential, SeNPs also present several challenges, particularly regarding toxicity concerns. These challenges and their implications for clinical translation are thoroughly explored, providing a balanced view of the current state and prospects of SeNPs in theranostic applications.

Synthesis and Superficial Modification "In Situ" of Copper Selenide (Cu2-x Se) Nanoparticles and Their Antibacterial Activity

Copper selenide nanoparticles (Cu2-x Se NPs) have received a lot of attention in recent decades due to their interesting properties and potential applications in various areas such as electronics, health, solar cells, etc. In this study, details of the synthesis and characterization of copper selenide nanoparticles modified with gum arabic (GA) are reported. Also, through transmission electronic microscopy (TEM) analysis, the transformation of the morphology and particle size of copper selenide nanoparticles in aqueous solution was studied. In addition, we present an antimicrobial study with different microorganisms such as Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Candida albiacans (C. albicans). Copper selenide nanoparticles were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry analysis (DSC) and TEM. XRD confirmed the crystal-line structure of the nanoparticles such as cubic berzelanite with a particle size of 6 nm ± 0.5. FTIR and TGA corroborated the surface modification of copper selenide nanoparticles with gum arabic, and DSC suggested a change in the structural phase from cubic to hexagonal. TEM analysis demonstrated that the surface modification of the Cu2-x Se NPs stabilized the nanostructure of the particles, preventing changes in the morphology and particle size. The antimicrobial susceptibility analysis of copper selenide nanoparticles indicated that they have the ability to inhibit the microbial growth of Staphylococcus aureus, Escherichia coli and Candida albicans.

Biogenic synthesis of selenium nanoparticles from Nyctanthes arbor-tristis L. and evaluation of their antimicrobial, antioxidant and photocatalytic efficacy

Biogenic synthesis of nanoparticles has been established as an environmentally benign and sustainable approach. This study emphasizes biosynthesis of selenium nanoparticles (SeNPs) utilizing leaf extract of Nyctanthes arbor-tritis L., well known for its abundant bioactive compounds. Various analytical techniques were employed for characterization of synthesized SeNPs. X-ray diffraction (XRD) spectroscopy confirmed the crystalline structure and revealed the average crystalline size of SeNPs to be 44.57 nm. Additionally, UV-Vis spectroscopy confirmed successful synthesis of SeNPs by validating the surface plasmon resonance (SPR) properties of SeNPs. FTIR analysis data revealed different bonds and their corresponding functional groups responsible for the synthesis and stability of synthesized SeNPs. DLS and zeta analysis revealed that 116.5 nm sized SeNPs were stable in nature. Furthermore, field emission scanning electron microscopy (FE-SEM) validated the spherical morphology of SeNPs with a size range of 60-80 nm. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) determined the concentration of SeNPs in the obtained colloidal solution. Antioxidant activity of synthesized SeNPs was evaluated employing DPPH and H2O2 assay, revealed that the synthesized SeNPs were effective antioxidant agent. Additionally, antimicrobial potential was evaluated against a panel of Gram-positive and Gram-negative bacteria and found to be effective at higher concentration of SeNPs. SeNPs also exhibited strong anti-biofilm activity while evaluated against various biofilm producing bacteria like Escherichia coli , Staphylococcus epidermidis and Klebsiella pneumonia. The cytotoxicity of the bio-synthesized SeNPs was evaluated against HEK 293 cell line, exhibited minimal toxicity even at concentration 100 μg/mL with 65% viable cells. SeNPs has also been evaluated for dye degradation which has indicated excellent photocatalytic activity of synthesized SeNPs. The experimental data obtained altogether demonstrated that synthesized SeNPs exhibited significant antimicrobial and anti-biofilm activity against various pathogens, and also showed significant antioxidant and photocatalytic efficiency.

A Review of the Antibacterial, Fungicidal and Antiviral Properties of Selenium Nanoparticles

The resistance of microorganisms to antimicrobial drugs is an important problem worldwide. To solve this problem, active searches for antimicrobial components, approaches and therapies are being carried out. Selenium nanoparticles have high potential for antimicrobial activity. The relevance of their application is indisputable, which can be noted due to the significant increase in publications on the topic over the past decade. This review of research publications aims to provide the reader with up-to-date information on the antimicrobial properties of selenium nanoparticles, including susceptible microorganisms, the mechanisms of action of nanoparticles on bacteria and the effect of nanoparticle properties on their antimicrobial activity. This review describes the most complete information on the antiviral, antibacterial and antifungal effects of selenium nanoparticles.

Allotropy of selenium nanoparticles: Colourful transition, synthesis, and biotechnological applications

Elemental selenium (Se⁰ ) nanomaterials undergo allotropic transition from thermodynamically-unstable to more stable phases. This process is significantly different when Se⁰ nanoparticles (NPs) are produced via physico-chemical and biological pathways. While the allotropic transition of physico-chemically synthesized Se⁰ is fast (minutes to hours), the biogenic Se⁰ takes months to complete. The biopolymer layer covering biogenic Se⁰ NPs might be the main factor controlling this retardation, but this still remains an open question. Phylogenetically-diverse bacteria reduce selenium oxyanions to red amorphous Se⁰ allotrope, which has low market value. Then, red Se⁰ undergoes allotropic transition to trigonal (metallic grey) allotrope, the end product having important industrial applications (e.g. semiconductors, alloys). Is it not yet clear whether biogenic Se⁰ presents any biological function, or it is mainly a detoxification and respiratory by-product. The better understanding of this transition would benefit the recovery of Se⁰ NPs from secondary resources and its targeted utilization with respect to each allotropic stage. This review article presents and critically discusses the main physico-chemical methods and biosynthetic pathways of Se⁰ (bio)mineralization. In addition, the article proposes a conceptual model for the resource recovery potential of trigonal selenium nanomaterials in the context of circular economy.

Microwave Assisted Synthesis of Antimicrobial Nano-Films from Water Hyacinth <i>(Eichhornia crassipes)</i> and Roselle <i>(Hibiscus sabdariffa</i>) Plant Extract

Cellulose based nanofilms have large applications in biomedical and related fields due to their antimicrobial properties. Their applicability depends upon purity of cellulose, composition, and structural properties of films. The nanofilms of cellulose extracted from Water Hyacinth (Eichhornia crassipes) and Roselle (Hibiscus Sabdariffa) plant possesses excellent properties for biomedical applications due to their biological origin and ZnO or other metal loading properties. Microwave assisted physical separation of cellulose provided excellent films formation properties and ZnO loading compared without any chemical traces. The presence of chemical impurities to affects structural, morphological properties and contact angle. It affects the biomedical applicability of cellulose based films. The microwave-based extraction was further assisted by use of polyethylene glycol with molecular weight 600, which increases the solubility and extractability of cellulose to 90 %. Formed films showed higher contact angle and hydrophobicity. This increased hydrophobicity of cellulosic nanofilms showed enhanced antimicrobial activities towards gram-negative and gram-positive bacteria by water hyacinth nanofilms. Thus, microwave-based synthesis of cellulose nanofilms resulted into enhanced microbial activities.

Photochemical Synthesis of Selenium Nanospheres of Tunable Size and Colloidal Stability with Simple Diketones

Temporal and spatial segregations are two fundamental requirements for the successful synthesis of nanoparticles (NPs). To obtain colloidally stable selenium nanospheres (SeNSs), surfactants or polymers are generally needed as structure-directing agents or stabilizers in the reduction approaches for SeNP synthesis. The addition of such chemicals sacrifices the purity of the obtained SeNPs and, therefore, is detrimental to the applications. Here, for the first time, we report that low-molecular weight (less than six carbons) diketones are excellent photoreductants for green and tunable synthesis of SeNPs, owing to their merits in temporal and spatial control. With simple diketones as the photoreductants, the resultant SeNPs were pure and colloidally stable with nice photoelectronic properties. This finding not only provides a useful strategy for the synthesis of SeNPs but also might be a milestone in the development of ketone photochemistry.

Raman Microspectroscopic Analysis of Selenium Bioaccumulation by Green Alga Chlorella vulgaris

Selenium (Se) is an element with many commercial applications as well as an essential micronutrient. Dietary Se has antioxidant properties and it is known to play a role in cancer prevention. However, the general population often suffers from Se deficiency. Green algae, such as Chlorella vulgaris, cultivated in Se-enriched environment may be used as a food supplement to provide adequate levels of Se. We used Raman microspectroscopy (RS) for fast, reliable, and non-destructive measurement of Se concentration in living algal cells. We employed inductively coupled plasma-mass spectrometry as a reference method to RS and we found a substantial correlation between the Raman signal intensity at 252 cm⁻¹ and total Se concentration in the studied cells. We used RS to assess the uptake of Se by living and inactivated algae and demonstrated the necessity of active cellular transport for Se accumulation. Additionally, we observed the intracellular Se being transformed into an insoluble elemental form, which we further supported by the energy-dispersive X-ray spectroscopy imaging.

Microwave-Assisted Green Synthesis and Antioxidant Activity of Selenium Nanoparticles Using Theobroma Cacao L. Bean Shell Extract

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.

Synthesis of a one-dimensional atomic crystal of vanadium selenide (V2Se9)

The synthesis and nanoscale dispersion of a new one-dimensional (1D) material, V2Se9, in which chain-shaped molecular units with strong covalent bonds are assembled in a crystal structure via weak van der Waals attraction between chains, were successfully carried out. V2Se9 is synthesized by solid-state reaction and additional heat treatment. The synthesized V2Se9 has excellent thermal stability up to 400 °C and has been experimentally confirmed to be dispersed up to ∼20 nm or less through a specific solvent dispersion. The covalently bonded V2Se9 chain, when isolated from its bulk material, is expected to exhibit unique quantum physical properties owing to the confinement of electrons in the 1D chain structure and the absence of inter-chain interactions, as demonstrated in the case of graphene and other 2D materials. Therefore, the novel 1D material of V2Se9, as an extension of the current 2D material, is expected to create a new class of materials that will be of significant interest to the materials science and nanotechnology communities for new device applications.

hsDNA groove binding, photocatalytic activity, and in vitro breast and colon cancer cell reducing function of greener SeNPs

Selenium nanoparticles (SeNPs) have attracted great attention because of their superior optical properties and wide utilization in biological and biomedical studies. This paper reports an environmentally benign procedure of greener monodispersible SeNP synthesis using the reducing power of Trigonella foenum-graecum extract, characterization and their protective effect against unfolded (Herring sperm DNA) hsDNA. We investigated the anti-cancer activity of SeNPs against MCF-7, MDA MB 435 and COLO-205 cells. The photocatalytic activity of SeNPs was investigated for the degradation of a Sunset Yellow FCF (SYFCF) dye using ultraviolet-B light. The reduction of the Se ion to SeNPs was monitored by ultraviolet-visible spectroscopy (UV-vis). The size and morphology of the SeNPs were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and Dynamic Light Scattering (DLS). The SeNPs were stable, and the diameter was homogeneous at around 5-12 nm. Interactions of various concentrations of SeNPs with hsDNA were systematically investigated by UV-vis, fluorescence, circular dichroism (CD), polarimetry and FTIR spectroscopy under physiological conditions. The results from fluorescence spectroscopy indicated that SeNPs quenched the fluorescence intensity of hsDNA with increasing concentrations. The modified Stern-Volmer quenching rate constant Ksv, binding constant K and binding sites n at different temperatures and the corresponding thermodynamic parameters ΔH°, ΔG° and ΔS° were calculated. Hoechst 33258 and methyl green (MG) site markers, melting experiment (Tm), viscosity measurements and sequence specificity verification by DNA bases clarified that SeNPs bind to hsDNA via a groove site. The rate of photocatalytic degradation of the SYFCF dye in the presence and absence of photocatalysts (SeNPs) was studied using UV-vis, the results showed appreciable degradation of the SYFCF dye. Our results suggested that nano Se can be used as a promising selenium species with potential application in cancer treatment. These nanoparticles were found to be the most active cytotoxic agent prepared in a new green synthesis manner, causing >50% inhibition of MCF-7, MDA MB-435 and COLO-205 cell proliferation at concentrations <10(-7) M. Hence these SeNPs could be recognized as promising materials for biomedical applications.

1,2,3-Selenadiazole-driven single family MSNCs of CdSe

Different 1,2,3-selenadiazoles derivatives were instantly prepared by hand grinding of the reactants via a solventless process and tested for their ability to act as a source of selenium used for synthesis of CdSe magic sized nanoclusters (MSNCs) in the size range of below 2 nm.

Microwave synthesis of bis(cycloalkeno)-1,4-diselenins: a novel source of Se for CdSe QDs

This paper describes the formation of a series of bis(cycloalkeno)-1,4-diselenins from the corresponding cycloalkeno-1,2,3-selenadiazoles by a microwave irradiation method. Additionally, for the first time ever, bis(cyclohepteno)-1,4-diselenin has been utilised as a novel selenium precursor for the preparation of CdSe quantum dots (QDs) by a microwave method.

Rapid microwave synthesis of white light emitting magic sized nano clusters of CdSe: role of oleic acid

A rapid green one-pot microwave synthesis of magic sized nano clusters of CdSe is presented using cycloalkeno-1,2,3-selenadiazoles as the Se source. The role of oleic acid in the cluster formation is discussed, which emit white light when illuminated with 365 nm light.

In situ SeO2promoted synthesis of CdSe/PPy and Se/PPy nanocomposites and their utility in optical sensing for detection of Hg2+ions

The reaction of selenium dioxide, a mild oxidizing agent, leads to the initiation of polymerization of pyrrole. The presence of cadmium metal can generate CdSe/PPy nanocomposites however, without it, Se/ PPy composites have been isolated.