Controlled synthesis of iron oxyhydroxide (FeOOH) nanoparticles using secretory compounds from Chlorella vulgaris microalgae

Nanosorbent based on coprecipitation of ZnO in goethite for competitive sorption of Cd(II)-Pb(II) and Cd(II)-Pb(II)-Ni(II) systems

Amongst the various water pollutants, heavy metal ions require special attention because of their toxic nature and effects on humans and the environment. Preserving natural resources will have positive impacts on living conditions by reducing diseases and water treatment by nanotechnology is effective in solving this problem owing to the properties of nanomaterials. In this study, a goethite nanoparticle was prepared by hydrothermal method, while ZnO/goethite nanocomposite by co-precipitation was developed. The nanoparticles were characterized using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transform Electron Microscopy (TEM), Thermogravimetric Differential Thermal Analysis (TGA-DTA), Dynamic Light Scattering (DLS), and Breunner-Emmet-Teller (BET) surface area analysis. The adsorption of Cd(II)-Pb(II) and Cd(II)-Pb(II)-Ni(II) ions systems on ZnO/goethite nanocomposite was investigated in a batch mode. The findings of the study showed that nanoparticles ZnO/goethite composite were mixed of spherical and rod-like shapes. The BET results revealed average particle sizes of 41.11 nm for nanoparticles for ZnO/goethite while TGA/DTA confirmed the stability of the adsorbents. The optimum adsorption capacities of the nanocomposite for Pb(II), Cd(II), and Ni(II) ions from the Pb-Cd-Ni ternary system were 415.5, 195.3, and 87.13 mg g-1, respectively. The adsorption isotherm data fitted well with the Langmuir isotherm model. The study concluded that the nanoparticle adsorbents are efficient for the remediation of toxic pollutants and are, therefore, recommended for wastewater treatment.

Iron nanoparticles as food additives and food supplements, regulatory and legislative perspectives

Recently, the use of nanotechnology in food has gained great interest. Iron nanoparticles with unique chemical, physical and structural properties allow their potential use mainly as iron fortifiers, colorants and antimicrobial agents. However, in the market we can find only supplements and food colorants based on iron nanoparticles. Their use in food fortification has so far been focused only on in vitro and in vivo experimental studies, since the toxicological evaluation of these studies has so far been the basis for the proposals of laws and regulations, which are still in an early stage of development. Therefore, the aim of this work was to summarize the use of the different forms of iron nanoparticles (oxides, oxyhydroxides, phosphates, pyrophosphates and sulfates) as food additives and supplements and to resume the perspectives of legislation regarding the use of these types of nanoparticles in the food industry.

Microalgae as a potential natural source for the green synthesis of nanoparticles

The increasing global population is driving the development of alternative sources of food and energy, as well as better or new alternatives for health and environmental care, which represent key challenges in the field of biotechnology. Microalgae represent a very important source material to produce several high-value-added bioproducts. Due to the rapid changes in the modern world, there is a need to build new materials for use, including those in the nanometer size, although these developments may be chronological but often do not occur at a time. In the last few years, a new frontier has opened up at the interface of biotechnology and nanotechnology. This new frontier could help microalgae-based nanomaterials to possess new functions and abilities. Processes for the green synthesis of nanomaterials are being investigated, and the availability of biological resources such as microalgae is continuously being examined. The present review provides a concise overview of the recent advances in the synthesis, characterization, and applications of nanoparticles formed using a wide range of microalgae-based biosynthesis processes. Highlighting their innovative and sustainable potential in current research, our study contributes towards the in-depth understanding and provides latest updates on the alternatives offered by microalgae in the synthesis of nanomaterials.

Nanoparticles from Microalgae and Their Biomedical Applications

Over the years, microalgae have been a source of useful compounds mainly used as food and dietary supplements. Recently, microalgae have been used as a source of metabolites that can participate in the synthesis of several nanoparticles through inexpensive and environmentally friendly routes alternative to chemical synthesis. Notably, the occurrence of global health threats focused attention on the microalgae application in the medicinal field. In this review, we report the influence of secondary metabolites from marine and freshwater microalgae and cyanobacteria on the synthesis of nanoparticles that were applied as therapeutics. In addition, the use of isolated compounds on the surface of nanoparticles to combat diseases has also been addressed. Although studies have proven the beneficial effect of high-value bioproducts on microalgae and their potential in medicine, there is still room for understanding their exact role in the human body and translating lab-based research into clinical trials.

Biocatalysis as a Green Approach for Synthesis of Iron Nanoparticles—Batch and Microflow Process Comparison

There is a growing need for production of iron particles due to their possible use in numerous systems (e.g., electrical, magnetic, catalytic, biological and others). Although severe reaction conditions and heavy solvents are frequently used in production of nanoparticles, green synthesis has arisen as an eco-friendly method that uses biological catalysts. Various precursors are combined with biological material (such as enzymes, herbal extracts, biomass, bacteria or yeasts) that contain chemicals from the main or secondary metabolism that can function as catalysts for production of nanoparticles. In this work, batch (“one-pot”) biosynthesis of iron nanoparticles is reviewed, as well as the possibilities of using microfluidic systems for continuous biosynthesis of iron nanoparticles, which could overcome the limitations of batch synthesis.

Photosynthetic microbes in nanobiotechnology: Applications and perspectives

Photosynthetic microbes like brown algae, red algae, green-algae and blue-green algae (cyanobacteria) are utilized extensively for various commercial and industrial purposes. However, in recent time, their application has shifted to nanotechnology. The synthesis of metal nanoparticles using algal resources is known as Phyconanotechnology. Due to various advantages of the photosynthetic microbes such as presence of bioactive molecules, scalability, high metal uptake and cultivability, these microbes form ideal sources for nanoparticle synthesis. The green synthesis of nanoparticles is a non-toxic and environment-friendly alternative compared to other hazardous chemical and physical routes of synthesis. Several species of algae are explored for the fabrication of metal and metal oxide nanoparticles. Various physical characterization techniques collectively contribute in defining the surface morphology of nanoparticles and the existing functional groups for bioreduction and stability. A wide range of nanostructured metals like gold, silver, copper, zinc, iron, platinum and palladium are fabricated using algae and cyanobacteria. Due to the unique properties of the phycogenic nanoparticles, biocompatibility and safety aspects, all of these metal nanoparticles have their applications in facets like infection control, diagnosis, drug delivery, biosensing and bioremediation. Herein, the uniqueness of the phycogenic nanoparticles along with their distinctive antibacterial, antifungal, antibiofilm, algaecidal, antiviral, anticancer, antioxidant, antidiabetic, dye degradation, metal removal and catalytic properties are featured. Lastly, this work highlights the various challenges and future perspectives for further exploration of the biogenic metal nanoparticles for development of nanomedicine and environmental remediation in the coming years.

Assessment of goethite-combined/modified biochar for cadmium and arsenic remediation in alkaline paddy soil

The opposed transformation of arsenic (As) and cadmium (Cd) in paddy soil postures numerous challenges for their simultaneous remediation. An incubation study was conducted on the immobilization of Cd and As by biochar (BC), goethite (G), goethite-combined biochar (BC + G), and goethite-modified biochar (GBC). The results showed that biochar effectively immobilized Cd while significantly increasing As mobility, whereas goethite effectively immobilized As more than Cd. BC + G treatment significantly decreased toxicity characteristics leaching procedure (TCLP) and CaCl₂-extractable Cd by 22.70% and 40.15%; meanwhile, TCLP and NaHCO₃-As were significantly reduced by 38.25% and 31.87%, respectively, compared with the control. This study found that GBC was the optimum amendment within the immobilization efficiency for CaCl₂-Cd (57.03%) and TCLP-As (61.11%). BC + G and GBC applications showed some interactions between biochar and goethite, which played an essential role in immobilizing Cd and As simultaneously. Therefore, GBC showed a great benefit in being a low-cost and efficient environmental amendment for Cd and As remediation in alkaline co-contaminated paddy soil.

Application of FeOOH Nano-Ellipsoids as a Novel Nano-Based Iron Supplement: an In Vivo Study

The possibility of employing FeOOH nano-ellipsoids as a novel shape nano-based iron supplement was investigated. Ferrous sulfate and nano-ellipsoids were daily administered by gavage at low and high dosages. After 1 month of treatment, the hematologic parameters along with serum and organs' iron contents were measured. Liver enzymes, total serum bilirubin, and LDH level were assayed to evaluate any possible toxicity. More investigation was also performed by organ index calculation and also pathologic studies. It was found that nano-ellipsoids are an effective iron supplement to improve iron-related blood parameters. Interestingly, low-dose nano-ellipsoids were even more effective than high-dose ferrous sulfate. Nano-ellipsoids had no considerable impact on the liver enzymes and serum bilirubin. Meanwhile, high-dose ferrous sulfate significantly increases liver enzyme activity. The increased serum LDH was also the only concern in the groups that were treated with high-dose ferrous sulfate and nano-ellipsoids. Pathologic evaluations revealed some signs of liver inflammation after supplementation with high dose nano-ellipsoids and also ferrous sulfate. Overall, these data indicate FeOOH nano-ellipsoids as a novel shape iron supplement to be employed at low dosage but with greater beneficial effects than high-dose ferrous sulfate.

Green route for recycling of low-cost waste resources for the biosynthesis of nanoparticles (NPs) and nanomaterials (NMs)-A review

Nowadays, nanoparticles (NPs) and nanomaterials (NMs) are used extensively in various streams such as medical science, solar energy, drug delivery, water treatment, and detection of persistent pollutants. Intensive synthesis of NPs/NMs carried out via physico-chemical technologies is deteriorating the environment globally. Therefore, an urgent need to adopt cost-effective and green technologies to synthesize NPs/NMs by recycling of secondary waste resources is highly required. Environmental wastes such as metallurgical slag, electronics (e-waste), and acid mine drainage (AMD) are rich sources of metals to produce NPs. This concept can remediate the environment on the one hand and the other hand, it can provide a future roadmap for economic benefits at industrial scale operations. The waste-derived NPs will reduce the industrial consumption of limited primary resources. In this review article, green emerging technologies involving lignocellulosic waste to synthesize the NPs from the waste streams and the role of potential microorganisms such as microalgae, fungi, yeast, bacteria for the synthesis of NPs have been discussed. A critical insight is also given on use of recycling technologies and the incorporation of NMs in the membrane bioreactors (MBRs) to improve membrane functioning and process performance. Finally, this study aims to mitigate various persisting scientific and technological challenges for the safe disposal and recycling of organic and inorganic waste for future use in the circular economy.

Assessment of modified Salvadora Persica for removal of 134Cs and 152+154Eu radionuclides from aqueous solution

Biosorption is a simple and economical method utilized to remove hazardous elements from a waste solution. In this study, a low-cost agricultural waste, Salvadora Persica, was modified with iron oxyhydroxide and evaluated as an economic biosorbent to remove cesium and europium radionuclides from their aqueous solutions. The modified biosorbent was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), elemental analysis as well as thermogravmetirc analysis (TGA). The sorption of ¹³⁴Cs and ^152+154Eu radioisotopes was investigated singly in a batch mode as a function of the solution pH, contact time, and the initial concentrations of the studied ions. The kinetic of the removal process was examined and it was found that the reaction obeys a pseudo-first-order model and the intraparticle diffusion is not the sole mechanism dominating the reaction. Temkin and Sips isotherm models provide the best fit for the equilibrium data. In addition, the sorption of cesium and europium ions was a spontaneous and endothermic process as inferred from thermodynamic studies. The reusability for the sorption of cesium and europium ions reveals the feasibility and efficacy of the modified biosorbent.

Size Tuned Synthesis of FeOOH Nanorods toward Self-Assembled Nanoarchitectonics

Various studies were performed to fabricate self-assembling nanoobjects out of noble metals, but a few efforts were made for engineering iron-based nanorods toward sell-assembling blocks. In this regard β-FeOOH nanorods were fabricated in various sizes to achieve iron-based rod nanoblocks with self-assembling potential. Hydrolysis of ferric ions in various concentrations was successfully developed as a novel approach to control the growth of β-FeOOH crystals and tuning the length of rods in the nano range, below 100 nm. It was found that the concentration of ferric ion has no effect on the widths of nanorods, but the length was affected. By increasing the concentration of ferric ions, an increase in the length of nanorods and an increase of aspect ratio occurred. All sizes of the resulting FeOOH nanorods exhibited mesoporous feature, but interestingly the hysteresis loops were different due to different pore patterns. In fact, pores on the larger particles were more uniform in size and shape. Nanorods of small length did not make suitable interactions toward ordered phase formation, but rods with the mean length of about 90 nm or longer, at a certain concentration, were able to form nematic phases. The large (∼+40 mV) zeta-potential of nanorods prevents formation of dense arrays, and just bundle-like structures were observed. These findings highlight the importance of size, surface charge, and concentration of nanoobjects in the formation of 3D structures. The developed technique in the fabrication of β-FeOOH nanorods provides pure structures that are free from any size-controlling agent. These pure structures are suitable for further functionalization or coating. Self-assembling nanoobjects is a developing field in nanotechnology, and therefore studies can help our understanding over the assembling process.

Enterobacter sp. Mediated Synthesis of Biocompatible Nanostructured Iron-Polysaccharide Complexes: a Nutritional Supplement for Iron-Deficiency Anemia

FDA has approved iron oxide nanoparticles (IONs) coated with organic compounds as a safe material with less toxic effects compared with the naked metal ions and nanoparticles. In this study, the biological and physicochemical characteristics of a nanostructured iron-polysaccharide complexes (Nano-IPC) biosynthesized by Enterobacter sp. were evaluated. Furthermore, the serum biochemical parameters, tissue iron level, red blood cell parameters, and organ ferritin of rats were measured for investigating the effect of the Nano-IPCs in comparison with FeSO₄ as a supplement for iron deficiency. The biosafety data demonstrated 35% increment of viability in Hep-G2 hepatocarcinoma cell lines when treated with nanoparticles (500 μg/mL) for 24 h. Besides, iron concentration in serum and tissue as well as the expression of ferritin L subunit in animals treated with the Nano-IPCs supplement were meaningfully higher than the FeSO₄-supplemented and negative control animals. Moreover, the expression level of ferritin H subunit and biochemical factors remained similar to the negative control animals in the Nano-IPC-supplemented group. These results indicated that Nano-IPCs can be considered as a nontoxic supplement for patients carrying iron-deficiency anemia (IDA).

New Perspectives on Iron-Based Nanostructures

Among all minerals, iron is one of the elements identified early by human beings to take advantage of and be used. The role of iron in human life is so great that it made an era in the ages of humanity. Pure iron has a shiny grayish-silver color, but after combining with oxygen and water it can make a colorful set of materials with divergent properties. This diversity sometimes appears ambiguous but provides variety of applications. In fact, iron can come in different forms: zero-valent iron (pure iron), iron oxides, iron hydroxides, and iron oxide hydroxides. By taking these divergent materials into the nano realm, new properties are exhibited, providing us with even more applications. This review deals with iron as a magic element in the nano realm and provides comprehensive data about its structure, properties, synthesis techniques, and applications of various forms of iron-based nanostructures in the science, medicine, and technology sectors.

Green and Economic Fabrication of Zinc Oxide (ZnO) Nanorods as a Broadband UV Blocker and Antimicrobial Agent

Zinc oxide (ZnO) nanoparticles have gained widespread interest due to their unique properties, making them suitable for a range of applications. Several methods for their production are available, and of these, controlled synthesis techniques are particularly favourable. Large-scale culturing of Chlorella vulgaris produces secretory carbohydrates as a waste product, which have been shown to play an important role in directing the particle size and morphology of nanoparticles. In this investigation, ZnO nanorods were produced through a controlled synthesis approach using secretory carbohydrates from C. vulgaris, which presents a cost-effective and sustainable alternative to the existing techniques. Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD) analysis, transmission electron microscopy (TEM), and UV-Vis spectroscopy were used to characterise the nanorods. The prepared nanorods exhibited a broad range of UV absorption, which suggests that the particles are a promising broadband sun blocker and are likely to be effective for the fabrication of sunscreens with protection against both UVB (290-320 nm) and UVA (320-400 nm) radiations. The antimicrobial activity of the prepared nanorods against Gram-positive and Gram-negative bacteria was also assessed. The nanostructures had a crystalline structure and rod-like appearance, with an average length and width of 150 nm and 21 nm, respectively. The nanorods also demonstrated notable antibacterial activity, and 250 μg/mL was determined to be the most effective concentration. The antibacterial properties of the ZnO nanorods suggest its suitability for a range of antimicrobial uses, such as in the food industry and for various biomedical applications.