Green Synthesized Iron-Coated Silver Nanoparticles: Economic Bimetallic Nanoparticles Potential Against Methicillin-Resistance Staphylococcus aureus

Iron coating was introduced as one of the novel techniques to improve physicochemical and biological properties of silver nanoparticles (AgNPs). In the current experiment, impact of iron coating on the antimicrobial potency of AgNPs was investigated against methicillin-resistance Staphylococcus aureus (MRSA). To obtain more accurate data about the antimicrobial potency of examined nanostructures, the experiment was done on the 10 isolates of MRSA which were isolated from skin lesions. AgNPs and iron-coated AgNPs (Fe@AgNPs) were fabricated based on a green one-pot reaction procedure. Minimal inhibitory concentration (MIC) of Fe@AgNPs was not significantly different with MIC of AgNPs against eight out of 10 examined MRSA isolates. Also, by iron coating a reduction in the minimal inhibitory concentration (MIC) of AgNPs was observed against two MRSA isolates. The average MIC of AgNPs against 10 MRSA isolates was calculated to be 2.16 ± 0.382 mg/mL and this value was reduced to 1.70 ± 0.638 mg/mL for Fe@AgNPs. However, this difference was not considered significant statistically (P-value > 0.05). From productivity point of view, it was found that iron coating would improve the productivity of the synthesis reaction more than fivefold. Productivity of AgNPs was calculated to be 1.02 ± 0.07 g/L, meanwhile this value was 5.25 ± 0.05 g/L for Fe@AgNPs. Iron coating may provide another economic benefit to reduce final price of AgNPs. It is obvious that the price of a particular nanostructure made of silver and iron is significantly lower than that of pure silver. These findings can be considered for the fabrication of economic and potent antimicrobial nanoparticles.

The potential of surface nano-engineering in characteristics of cobalt-based nanoparticles and biointerface interaction with prokaryotic and human cells

Cobalt-based nanoparticles (CBNPs) have recently received great attention in biomedical studies; however, the possible biotoxicity of these nanoparticles (NPs) has remained a foremost concern that should be addressed. As surface functionalization is one of the helpful proposed solutions, we aimed to apply Lipoamino acids (LAAs) as a coating agent to improve biocompatibility. To this purpose, cobalt oxide, cobalt ferrite, and iron oxide nanoparticles (IONs) were synthesized with and without 2-amino-hexadecanoic acid coating to assess the impacts of LAA coating on characteristics and biocompatibility of CBNPs in human cells and compare with IONs, a widely used magnetic NPs in biomedicine. Antibacterial activities of NPs were evaluated against four Gram-negative and Gram-positive bacteria species to assess their biointerface interaction with prokaryotic cells. In addition, the antibacterial activities of synthesized NPs were compared to silver NPs, one of the widely used antimicrobial NPs and standard antibiotics (ampicillin). The structural characteristics properties of NPs were analyzed using TEM, FE-SEM, EDS, FTIR, XRD, and VSM. These NPs exhibited sphere-like to polygon-like morphology with desirable mean size. CBNPs displayed dose-dependent cytotoxicity and antimicrobial activities against human cell lines and all tested microbial species, as well as more cytotoxicity and bacterial inhibition compared to IONs. Besides, the results revealed that LAA coating could significantly improve the biocompatibility and antibacterial activity of NPs while impacting magnetic properties. To sum up, it seems that surface functionalization could provide more potent tools for bioapplications with improving biocompatibility and bacterial inhibition of CBNPs, though; further studies are needed in this regard.

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.

Synthesis of mesoporous antimicrobial herbal nanomaterial-carrier for silver nanoparticles and antimicrobial sensing

Herbal nanoparticles (HNPs) were introduced as a novel generation of antimicrobial nanoparticles. But in the battle against superbugs we need nanostructures with boosted antimicrobial potency. So in the current experiment, for the first time a green approach was developed for the silver functionalization of HNPs which were fabricated from an antimicrobial herb Thymus vulgaris. Silver functionalized HNPs (AgHNPs) were found to be mesoporous and were further fortified with antimicrobial compounds. The resulted structures were re-tested against MRSA and P. aeruginosa as superbugs. It was found that silver functionalization can provide eight-fold increase in the antimicrobial potency of HNPs. Moreover, MIC was reduced from 20 mg/mL to 2.5 mg/mL. Another eight-fold reduction in the MIC (0.3 mg/mL) was achieved by fortification with antimicrobial compounds. So, the antimicrobial potency of HNPs was successfully increase approximately up to 64-folds. Obtained results illustrated that silver functionalization and fortification with antimicrobial compounds can be considered as effective approaches to achieve HNPs with boosted antimicrobial potency. These nanostructures have the potency to be loaded with other antimicrobial compound such as antibiotics toward synergistic effects of AgNPs and antibiotics. Resulted nanostructures can be employed in the formulation of powerful topical and surface disinfectants against superbugs. Also, these particles can be considered as a next generation of boosted antimicrobial nanostructures.

A Study of l-Lysine-Stabilized Iron Oxide Nanoparticles (IONPs) on Microalgae Biofilm Formation of Chlorella vulgaris

Despite iron-based nanoparticles gaining huge attraction in various field of sciences and technology, their application rises ecological concerns due to lack of studies on their interaction with microbial cells populations and communities, such as biofilms. In this study, Chlorella vulgaris cells were employed as a model of aquatic microalgae to investigate the impacts of l-lysine-coated iron oxide nanoparticles (lys@IONPs) on microalgal growth and biofilm formation. In this regard, C. vulgaris cells were exposed to different concentrations of lys@IONPs and the growth of cells was evaluated by OD600 and biofilm formation was analyzed using crystal violet staining throughout 12 days. It was revealed that low concentration of nanoparticles (< 400 µg/mL) can promote cell growth and biofilm formation. However, higher concentrations have an adverse effect on microalgal communities. It is interesting that microalgal growth and biofilm are concentration- and exposure time-dependent to lys@IONPs. Over long period (~ 12 days) exposure to high concentrations of nanoparticles, cells can adapt with the condition, so growth was raised and biofilm started to develop. Results of the present study could be considered in ecological issues and also bioprocesses using microalgal cells.

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.

Impact of magnetic immobilization on the cell physiology of green unicellular algae Chlorella vulgaris

Cell immobilization on the magnetic nanoparticles (MNPs) and magnetic harvesting is a novel approach for microalgal cells separation. To date, the effect of these nanoparticles on microalgal cells was only studied over a short period of time. More studies are hence needed for a better understanding of the magnetic harvesting proposes or environmental concerns relating to long-term exposure to nanoparticles. In this study, the impact of various concentrations of MNPs on the microalgal cells growth and their metabolic status was investigated over 12 days. More than 60% reduction in mitochondrial activity and pigments (chlorophyll a, chlorophyll b, and carotenoids) content occurred during the first 6 days of exposure to ≥50 µg/mL nanoparticles. However, more than 50% growth inhibitory effect was seen at concentrations higher than 400 µg/mL. Exposure to MNPs gradually induced cellular adaptation and after about 6 days of exposure to stress generating concentrations (˂400 µg/mL) of IONs, microalgae could overcome the imposed damages. This work provides a better understanding regarding the environmental impact of MNPs and appropriate concentrations of these particles for future algal cells magnetic immobilization and harvesting.

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.

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

FeOOH nanoparticles are commonly synthesized at very high temperature and pressure that makes the process energy consuming and non-economic. Recently, novel approaches were developed for the fabrication of these particles at room temperature. But, the main problem with these methods is that the prepared structures are aggregates of ultra-small nanoparticles where no intact separate nanoparticles are formed. In this study, for the first time, secretory compounds from Chlorella vulgaris cells were employed for the controlled synthesis of FeOOH nanoparticles at room atmosphere. Obtained particles were found to be goethite (α-FeO(OH)) crystals. Controlled synthesis of FeOOH nanoparticles resulted in uniform spherical nanoparticles ranging from 8 to 17 nm in diameter with 12.8 nm mean particle size. Fourier-transform infrared and elemental analyses were indicated that controlled synthesized nanoparticles have not functionalized with secretory compounds of C. vulgaris, and these compounds just played a controlling role over the synthesis reaction.

Magnetic Immobilization of Pichia pastoris Cells for the Production of Recombinant Human Serum Albumin

Magnetic immobilization as a novel technique was used to immobilize recombinant Pichia pastoris (GS115 Albumin) cells to produce human serum albumin (HSA). In this regard, magnetic nanoparticles (MNPs) coated with amino propyl triethoxy silane (APTES) were synthesized. P. pastoris cells were decorated with MNPs via nonspecific interactions. Decorated cells were magneto-responsible and easily harvested by applying an external magnetic field. The efficiency of magnetic immobilization (E_i) for cell removal was in direct relation with the MNP concentration and time of exposure to the magnetic field. By increasing the nanoparticles concentration, cells were harvested in a shorter period. Complete cell removal (E_i ≈ 100) was achieved in ≥0.5 mg/mL of MNPs in just 30 s. HSA is produced in an extremely high cell density (OD ~20) and it is the first time that magnetic immobilization was successfully employed for harvesting such a thick cell suspension. After 5 days of induction the cells, which were immobilized with 0.25 to 1 mg/mL of nanoparticles, showed an increased potency for recombinant HSA production. The largest increase in HSA production (38.1%) was achieved in the cells that were immobilized with 0.5 mg/mL of nanoparticles. These results can be considered as a novel approach for further developments in the P. pastoris-based system.

Study on the interaction of anti-inflammatory drugs with human serum albumin using molecular docking, quantitative structure-activity relationship, and fluorescence spectroscopy

The interaction of 14 anti-inflammatory drugs with human serum albumin (HSA) was investigated using fluorescence quenching, molecular docking studies, and quantitative structure-activity relationship (QSAR) methodology. Binding of anti-inflammatory drugs to HSA plays a fundamental role in their transport, distribution, delivery, and elimination. Binding constants of these drugs to HSA, obtained using the fluorescence quenching method, were within the range 0.01 × 10⁴  M^-1 (acetaminophen) to 1881.05 × 10⁴  M^-1 (meloxicam). Binding sites and binding constants of these anti-inflammatory drugs were estimated using molecular docking. Inspection of the obtained values for docking score, logK_b and K_b , showed that the drugs in this data set have a relatively strong binding constant for HSA. QSAR modelling was applied for binding constants obtained from fluorescence quenching and theoretical molecular descriptors. This modelling led to a linear two-parameter model with a correlation coefficient of 0.95 and adequate robustness. The descriptor results showed the importance of a bonding network and electronegativity as the discriminative structural factors in binding affinity for the HSA molecule.

Xanthan Gum Capped ZnO Microstars as a Promising Dietary Zinc Supplementation

Zinc is one of the essential trace elements, and plays an important role in human health. Severe zinc deficiency can negatively affect organs such as the epidermal, immune, central nervous, gastrointestinal, skeletal, and reproductive systems. In this study, we offered a novel biocompatible xanthan gum capped zinc oxide (ZnO) microstar as a potential dietary zinc supplementation for food fortification. Xanthan gum (XG) is a commercially important extracellular polysaccharide that is widely used in diverse fields such as the food, cosmetic, and pharmaceutical industries, due to its nontoxic and biocompatible properties. In this work, for the first time, we reported a green procedure for the synthesis of ZnO microstars using XG, as the stabilizing agent, without using any synthetic or toxic reagent. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) were used to study the structure, morphology, and size of the synthesized ZnO structures. The results showed that the synthesized structures were both hexagonal phase and starlike, with an average particle size of 358 nm. The effect of different dosages of XG-capped ZnO nanoparticles (1–9 mM) against Gram-negative (Escherichia coli) and Gram-positive (Bacillus licheniformis, Bacillus subtilis, and Bacillus sphaericus) bacteria were also investigated. Based on the results, the fabricated XG-capped ZnO microstars showed a high level of biocompatibility with no antimicrobial effect against the tested microorganisms. The data suggested the potential of newly produced ZnO microstructures for a range of applications in dietary supplementation and food fortification.