Iron Oxide Research Articles

Synthesis of highly luminescent core-shell nanoprobes in a single pot for ofloxacin detection in blood serum and water.

Antibiotics are commonly used as antibacterial medications due to their extensive and potent therapeutic properties. However, the overconsumption of these chemicals leads to their accumulation in the human body via the food chain, amplifying drug resistance and compromising immunity, thus presenting a significant hazard to human health. Antibiotics are classified as organic pollutants. Therefore, it is crucial to conduct research on precise methodologies for detecting antibiotics in many substances, including food, pharmaceutical waste, and biological samples like serum and urine. The methodology described in this research paper introduces an innovative technique for producing nanoparticles using silica as the shell material, iron oxide as the core material, and carbon as the shell dopant. By integrating a carbon-doped silica shell, this substance acquires exceptional fluorescence characteristics and a substantial quantum yield value of 80%. By capitalising on this characteristic of the substance, we have effectively constructed a fluorescent sensor that enables accurate ofloxacin analysis, with a detection limit of 1.3 × 10-6 M and a linear range of concentrations from 0 to 120 × 10-6 M. We also evaluated the potential of CSIONPs for OLF detection in blood serum and tap water analysis. The obtained relative standard deviation values were below 3.5%. The percentage of ofloxacin recovery from blood serum ranged from 95.52% to 103.28%, and from 89.9% to 96.0% from tap water.

Degradation of pharmaceuticals and other emerging pollutants employing bi-metal catalysts/magnesium and/or (green) hydrogen in aqueous solution.

Contaminations by pharmaceuticals, personal care products, and other emerging pollutants in water resources have become a seriously burgeoning issue of global concern in the first third of the twenty-first century. As societal reliance on pharmaceuticals continues to escalate, the inadvertent introduction of these substances into water reservoirs poses a consequential environmental threat. Therefore, the aim of this study was to investigate reductive degradation, particularly, catalytic hydrogenation regarding model pollutants such as diclofenac (DCF), ibuprofen (IBP), 17α-ethinylestradiol (EE2), or bisphenol-A (BPA), respectively, in aqueous solutions at lab scale. Iron bimetals (zero valent iron, ZVI, and copper, Cu, or nickel, Ni) as well as zero valent magnesium (Mg, ZVM) in combination with rhodium, Rh, or palladium, Pd, as hydrogenation catalysts (HK), were investigated. Studies were executed through various short-term batch experiments, with multiple sample collections, over a total range of 120min. The results indicated that DCF was attenuated at over 90 % when exposed to Fe-Cu or a Fe-Ni bimetal (applied as a single model pollutant). However, when DCF was part of a mixture alongside with IBP, EE2, and BPA, the attenuation efficacy decreased to 79 % with Fe-Cu and 23 % with Fe-Ni. Conversely, both IBP and BPA exhibit notably low attenuation levels with both bimetals, less than 50 %, both deployed as single substances or in mixtures. No reaction (degradation) products could be identified employing LC-MS, but sometimes a release of the parent pollutant when applying an acetic acid buffer could be noted to a certain extent, suggesting adsorption processes on corrosion products such as iron hydroxide and/or oxides. Surprisingly, Mg in combination with Rh (Rh-HK) or Pd (Pd-HK) showed a significantly rapid decrease in the concentrations of DCF, EE2, and BPA, in part up to approximately 100 %, that is, within a few minutes only in part due to hydrogenation degradation reactions (related reaction products could actually be identified by LC-MS; adsorption processes were not observed here). Moreover, kinetic modeling of the DCF degradation with Mg-Rh-HK was conducted at different temperatures (15 °C, 20 °C, 25 °C, 35 °C) and varied initial concentrations (2.5mg/L, 5.0mg/L, 7.5mg/L, 10.0mg/L). The outcomes prove that the degradation of DCF at the Rh-HK's surface followed a modified first-order kinetics, most probably by catalytic hydrodehalogenation and subsequent hydrogenation of the aromatic moieties (molecular hydrogen was provided by the corrosion of Mg). From the determined reaction rate constants at four different temperatures, the activation energy was estimated to be 59.6kJ/mol by means of the Arrhenius equation what is in good agreement with similar results reported in the literature. This coupled hydrodehalogenation and hydrogenation approach may be upscaled into a new promising technical process for comprehensively removing such pharmaceuticals and similar pollutants in sewage plants in a single step, furthermore, even in combination with adsorption by activated carbon and/or ozonation which have already been established at some sewage plants in Switzerland and Germany recently.

A turbidity-based study of removing polyvinyl chloride nanoplastics using magnetic biochar

Magnetic biochars (MBCs) can quickly and efficiently remove polystyrene nanoplastics (NPs) from water. However, the removal efficiency of other types of NPs by different MBCs remains unknown. In this study, the removal performance of polyvinyl chloride NPs (PVC-NPs) by magnetic corncob biochar (MCCBC) and magnetic walnut shell biochar (MWSBC) was evaluated by measuring turbidity. The results indicate rapid adsorption of PVC-NPs onto MCCBC and MWSBC, reaching equilibrium within 1 h. The removal efficiencies of PVC-NPs by MCCBC and MWSBC were 94% and 92%, respectively. The relatively higher PVC-NPs removal capacity by MCCBC resulted from the greater amount of iron oxide on its surface, creating a rougher surface. The presence of monovalent ions (K+, Na+, Cl-, NO-3) promoted the removal of PVC-NPs by MWSBC, but caused a reduction in the adsorption of PVC-NPs on MCCBC. In contrast, divalent ions (Mg2+, Ca2+, and SO2-4) significantly inhibited the removal efficiency of PVC-NPs by competing for adsorption sites on MBCs (p < 0.01). Increasing the ionic strength inhibited the removal efficiency of PVC-NPs by MBCs. In addition, the highest removal efficiency of PVC-NPs was obtained at pH 5.0–7.0. Apart from adsorbing onto the surface of MBCs and becoming trapped within their pores, PVC-NPs can be magnetized by iron oxides. Moreover, PVC-NPs could aggregate with the small fragments of MBCs, thus allowing for easy removal by a magnet. The results provide new insight into the investigation of techniques to remove NPs other than PS from water.

Reusable adsorbent of magnetite in mesoporous carbon for antibiotic removal.

This study aims to evaluate the feasibility of an innovative reusable adsorbent through adsorption-degradation sequence for antibiotic removal from water. The magnetite/mesoporous carbon adsorbent was prepared using a two-step method of (i) in situ impregnation of magnetite precursor during resorcinol formaldehyde polymerization and (ii) pyrolysis at elevated temperature (800 °C). XRD spectra confirmed that magnetite (Fe3O4) was the only iron oxide species present in the adsorbent, and thermogravimetric analysis revealed that its content was 10 wt%. Nitrogen sorption analysis showed that Fe3O4/carbon features a high fraction of mesopores (> 80 vol.%) and a remarkable specific surface area value (246 m2g-1), outstanding properties for water treatment. The performance of the adsorbent was examined in the uptake of three relevant antibiotics. The maximum adsorption uptakes were ca. 76mgg-1, ca. 70mgg-1, and ca. 44mgg-1 for metronidazole, sulfamethoxazole, and ciprofloxacin, respectively. All adsorption curves were successfully fitted with Langmuir equilibrium model. The regeneration of adsorbent was carried out using Fenton oxidation under ambient conditions. After three consecutive runs of adsorption-regeneration, Fe3O4/carbon maintained its performance almost unchanged (up to 95% of its adsorption capacity), which highlights the high reusability of the adsorbent.

Development and characterization of lipid nanocapsules loaded with iron oxide nanoparticles for magnetic targeting to the blood-brain barrier.

Brain drug delivery is severely hindered by the presence of the blood-brain barrier (BBB). Its functionality relies on the interactions of the brain endothelial cells with additional cellular constituents, including pericytes, astrocytes, neurons, or microglia. To boost brain drug delivery, nanomedicines have been designed to exploit distinct delivery strategies, including magnetically driven nanocarriers as a form of external physical targeting to the BBB. Herein, a lipid-based magnetic nanocarrier prepared by a low-energy method is first described. Magnetic nanocapsules with a hydrodynamic diameter of 256.7 ± 8.5nm (polydispersity index: 0.089 ± 0.034) and a ξ-potential of -30.4 ± 0.3mV were obtained. Transmission electron microscopy-energy dispersive X-ray spectroscopy analysis revealed efficient encapsulation of iron oxide nanoparticles within the oily core of the nanocapsules. Both thermogravimetric analysis and phenanthroline-based colorimetric assay showed that the iron oxide percentage in the final formulation was 12 wt.%, in agreement with vibrating sample magnetometry analysis, as the specific saturation magnetization of the magnetic nanocapsules was 12% that of the bare iron oxide nanoparticles. Magnetic nanocapsules were non-toxic in the range of 50-300μg/mL over 72h against both the human cerebral endothelial hCMEC/D3 and Human Brain Vascular Pericytes cell lines. Interestingly, higher uptake of magnetic nanocapsules in both cell types was evidenced in the presence of an external magnetic field than in the absence of it after 24h. This increase in nanocapsules uptake was also evidenced in pericytes after only 3h. Altogether, these results highlight the potential for magnetic targeting to the BBB of our formulation.

Direct Affinity Ligand Immobilization onto Bare Iron Oxide Nanoparticles Enables Efficient Magnetic Separation of Antibodies.

Magnetic separation is a promising alternative to chromatography for enhancing the downstream processing (DSP) of monoclonal antibodies (mAbs). However, there is a lack of efficient magnetic particles for successful application. Aiming to fill this gap, we demonstrate the suitability of bare iron oxide nanoparticles (BION) with physical site-directed immobilization of an engineered Protein A affinity ligand (rSpA) as an innovative magnetic material. The rSpA ligand contains a short peptide tag that enables the direct and stable immobilization onto the uncoated BION surface without commonly required laborious particle activation. The resulting BION@rSpA have beneficial characteristics outperforming conventional Protein A-functionalized magnetic particles: a simple, fast, low-cost synthesis, a particle size in the nanometer range with a large effective specific surface area enabling large immunoglobulin G (IgG) binding capacity, and a high magnetophoretic velocity advantageous for fast processing. We further show rapid interactions of IgG with the easily accessible rSpA ligands. The binding of IgG to BION@rSpA is thereby highly selective and not impeded by impurity molecules in perfusion cell culture supernatant. Regarding the subsequent acidic IgG elution from BION@rSpA@IgG, we observed a hampering pH increase caused by the protonation of large iron oxide surfaces after concentrating the particles in 100 mM sodium acetate buffer. However, the pH can be stabilized by adding 50 mM glycine to the elution buffer, resulting in recoveries above 85% even at high particle concentrations. Our work shows that BION@rSpA enable efficient magnetic mAb separation and could help to overcome emerging bottlenecks in DSP.

Unlocking the potential of biochar: an iron-phosphorus-based composite modified adsorbent for adsorption of Pb(II) and Cd(II) in aqueous environments and response surface optimization of adsorption conditions.

In this work, iron-phosphorus based composite biochar (FPBC) was prepared by modification with potassium phosphate and iron oxides for the removal of heavy metal ions from single and mixed heavy metal (Pb and Cd) solutions. FTIR and XPS characterization experiments showed that the novel modified biochar had a greater number of surface functional groups compared to the pristine biochar. The maximum adsorption capacities of FPBC for Pb(II) and Cd(II) were 211.66mg·g-1 and 94.08mg·g-1 at 293K. The adsorption of Pb(II) and Cd(II) by FPBC followed the proposed two-step adsorption kinetic model and the Freundlich isothermal adsorption model, suggesting that the mechanism of adsorption of Pb(II) and Cd(II) by FPBC involved chemical adsorption of multiple layers. Mechanistic studies showed that the introduction of -PO4 and -PO3 chemisorbed with Pb(II) and Cd(II), and the introduction of -Fe-O increased the ion exchange with Pb(II) and Cd(II) during the adsorption process and produced precipitates such as Pb3Fe(PO4)3 and Cd5Fe2(P2O7)4. Additionally, the abundant -OH and -COOH groups also participated in the removal of Pb(II) and Cd(II). In addition, FPBC demonstrated strong selective adsorption of Pb(II) in mixed heavy metal solutions. The Response Surface Methodology(RSM) analysis determined the optimal adsorption conditions for FPBC as pH 5.31, temperature 26.01°C, and Pb(II) concentration 306.30mg·L-1 for Pb(II). Similarly, the optimal adsorption conditions for Cd(II) were found to be pH 5.66, temperature 39.34°C, and Cd(II) concentration 267.68mg·L-1. Therefore, FPBC has the potential for application as a composite-modified adsorbent for the adsorption of multiple heavy metal ions.

Synergy between Fe-Co oxide catalysts supported over HZSM-5 for direct conversion of methane to methanol

The direct conversion of methane to methanol over iron and cobalt oxide based composite catalysts supported over HZSM-5 was carried out in a fixed-bed micro reactor under changing process parameters and catalyst compositions. The prepared catalysts were well characterized by various techniques including N2 adsorption desorption, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), pyridine FTIR, X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and temperature programmed reduction (H2-TPR). The characterization results revealed the presence of various reducible iron and cobalt oxide species depending on the Fe/Co molar ratio and total metal oxide loading. Moreover, the XPS and UV–vis spectroscopic results also confirmed the variation of Fe2+/Fe3+ and Co2+/Co3+ species depending on the Fe-Co molar ratio which had strong influence on the performance of the composite catalysts. It was found that the cobalt species favours the formaldehyde formation whereas the iron species promotes the formic acid formation in their respective pure supported oxide catalysts. However, the synergistic effect of iron and cobalt oxide in equimolar ratio in composite catalysts appeared as effective for achieving highest yield of methanol. The methanol selectivity was also influenced by the alteration of various studied process parameters. The higher reaction temperature favoured the overoxidation of methanol to CO2 whereas the methanol selectivity increased with increasing the methane to oxygen ratio. The lattice to adsorbed oxygen ratio also had strong influence on the activity of composite catalysts and methanol selectivity. The highest methanol yield of 1.87% was achieved at the methane conversion of 42.81 % with the 20Fe1Co1Z catalyst at 873 K reaction temperature with CH4/O2 ratio of 2:1 and WHSV of 1030 ml hr−1 gcat−1.

Effect of seawater and dissolved cations on scorodite synthesis via iron coprecipitation

In recent years, one of the more effective developments in the fixation of arsenic from nonferrous waste has been the synthesis of scorodite via the co-precipitation of arsenic with iron during Fe(II) oxidation. This work examines the impact of cation impurities on the process with the aim of widening the application of this approach to incorporate the use of seawater and the treatment of ferrous metallurgy waste. Scorodite formation was promoted by the presence of cations in the order of Cu2+ >> Zn2+ > Al3+ > Ca2+ ∼ Mg2+, with differences in precipitation behaviour, yield and kinetics due to specific cation effects on iron oxidation. A grain size increase was observed with Cu, while the opposite was found with Al, attributed to crystallisation from solution over epitaxial growth. The use of seawater decreased As precipitation by <4 % without affecting grain size, showing the potential to be utilised as reaction medium. While the presence of Na+ hinders As precipitation, the impact appears less pronounced with seawater due to competing effects from other cations. Since scorodite precipitation is slowed down by high Fe(III) in the feed, a pre-reduction approach with Al, Cu and Zn base metals was examined for conversion of Fe(III) in metallurgical waste to Fe(II) prior to co-precipitation with As. While this produced stable scorodite precipitates, the yield and presence of unstable by-products were impacted by the method of reductant addition.

Superparamagnetic Iron Oxide-Erastin-Polyethylene Glycol Nanotherapeutic Platform: A Ferroptosis-Based Approach for the Integrated Diagnosis and Treatment of Nasopharyngeal Cancer.

Erastin can induce ferroptosis in tumor cells as an effective small molecule inhibitor. However, its application is hampered by a lack of water solubility. This study investigated the effects of superparamagnetic iron oxide (SPIO)-erastin-polyethylene glycol (PEG) nanoparticles prepared by loading SPIO-PEG nanoparticles with erastin on ferroptosis. SPIO-erastin-PEG nanoparticles exhibited square and spherical shapes with good dispersibility. The zeta potential and hydrodynamic size of SPIO-erastin-PEG were measured as (-37.68 ± 2.706) mV and (45.75 ± 18.88) nm, respectively. On T2-weighted imaging, the nanosystem showed significant contrast enhancement compared to no-enhancement magnetic resonance imaging (MRI). SPIO-erastin-PEG induced ferroptosis by increasing reactive oxygen species and iron content and promoting the accumulation of lipid peroxides and the degradation of glutathione peroxidase 4. Pharmacokinetic experiments revealed a half-life of 1.25 ± 0.05 h for the SPIO-erastin-PEG solution in circulation. Moreover, significant antitumorigenic effects of SPIO-erastin-PEG have been demonstrated in 5-8F cells and mouse-bearing tumors. These results indicated that the synthesized SPIO-erastin-PEG nanoplatform could induce ferroptosis effects in vitro and in vivo while exhibiting favorable physical characteristics. This approach may provide a new strategy for theranostic nanoplatform for nasopharyngeal cancer.

Alteration in the Raman spectra of characteristic rock‐forming silicate mixtures due to micrometeorite bombardment

AbstractInnovative techniques are required for the in situ investigation of the surfaces of planetary bodies when landings are planned. Raman spectroscopy turned out as an excellent tool for fast mineralogical analyses on space missions. Contribution from a photoluminescence signal is not unexpected and is likely to be even more pronounced on celestial surfaces with a dilute or absent atmosphere exposed to strong space weathering, for example, micrometeorite bombardment. Such signals were found, for example, in Raman analysis of the probes from sample‐return missions. While photoluminescence is generally considered as an accompanying undesired product in the Raman spectral measurement, our studies show that some analytical information can be derived from this signal, and even more, due to the specific correlation of luminescence intensity with space weathering products. Therefore, we investigate the Raman spectra alteration of characteristic rock‐forming mineral mixtures (olivine, pyroxene and plagioclase) by micrometeorite bombardment, which is simulated by nanosecond‐pulse laser irradiation. The changes in the minerals are strongly dependent on the composition and structure. They range from disappearing changes in the minerals with simple chemistry and structure to complete amorphization of minerals with relatively low melting enthalpy. With Raman spectroscopy, we found out that the photoluminescence signals show resonant or anti‐resonant changes to specific mineral phases and amorphization. Furthermore, ablation‐induced iron nanoparticles of minerals containing Fe are detectable by Raman spectroscopy due to their alteration into iron oxides. Trapped volatiles in the matrices are analysed due to the formation of the compounds containing them. This broad spectrum of results indicating specific change phenomena due to space weathering can be effectively used for in situ Raman analysis in planetary missions.

Optimizing the lyophilization of Lumbricus terrestris erythrocruorin

Haemorrhagic shock is a leading cause of death worldwide. Blood transfusions can be used to treat patients suffering severe blood loss but donated red blood cells (RBCs) have several limitations that limit their availability and use. To solve the problems associated with donated RBCs, several acellular haemoglobin-based oxygen carriers (HBOCs) have been developed to restore the most important function of blood: oxygen transport. One promising HBOC is the naturally extracellular haemoglobin (i.e. erythrocruorin) of Lumbricus terrestris (LtEc). The goal of this study was to maximise the portability of LtEc by lyophilising it and then testing its stability at elevated temperatures. To prevent oxidation, several cryoprotectants were screened to determine the optimum formulation for lyophilisation that could minimise oxidation of the haem iron and maximise recovery. Furthermore, samples were also deoxygenated prior to storage to decrease auto-oxidation, while resuspension in a solution containing ascorbic acid was shown to partially reduce LtEc that had oxidised during storage (e.g. from 42% Fe3+ to 11% Fe3+). Analysis of the oxygen equilibria and size of the resuspended LtEc showed that the lyophilisation, storage, and resuspension processes did not affect the oxygen transport properties or the structure of the LtEc, even after 6 months of storage at 40 °C. Altogether, these efforts have yielded a shelf-stable LtEc powder that can be stored for long periods at high temperatures, but future animal studies will be necessary to prove that the resuspended product is a safe and effective oxygen transporter in vivo.

Comparison of MAF-32 and a One-Pot Synthesized Superparamagnetic Iron Oxide/MAF-32 Composite for the Adsorption of Diclofenac

The global presence of pharmaceutical pollutants in water sources represents a burgeoning public health concern. Recent studies underscore the urgency of addressing this class of emerging contaminants. In this context, our work focuses on synthesizing a composite material, FexOy/MAF-32, through a streamlined one-pot reaction process, as an adsorbent for diclofenac, an emerging environmental contaminant frequently found in freshwater environments and linked to potential toxicity towards several organisms such as fish and mussels. A thorough characterization was performed to elucidate the structural composition of the composite. The material presents magnetic properties attributed to its superparamagnetic behavior, which facilitates the recovery efficiency of the composite post-diclofenac adsorption. Our study further involves a comparative analysis between the FexOy/MAF-32 and a non-magnetic counterpart, comprised solely of 2-ethylimidazolate zinc polymer. This comparison aims to discern the relative advantages and disadvantages of incorporating magnetic iron oxide nanoparticles in the contaminant removal process facilitated by a coordination polymer. Our findings reveal that even a minimal incorporation of iron oxide nanoparticles substantially enhanced the composite’s overall performance in pollutant adsorption.

Contrasting magma chemistry in the Candelaria IOCG district caused by changing tectonic regimes

Iron oxide-copper-gold (IOCG) deposits are a vital source of copper and critical elements for emerging clean technologies. Andean-type IOCG deposits form in continental arcs undergoing extension, and they have a temporal relationship with magmatism although they do not exhibit a close spatial relation with the causative intrusions. The processes required to form IOCG deposits and their potential connections to iron oxide–apatite (IOA)-type mineralization remain poorly constrained, as well as the characteristics of magmatism linked to both deposit types. Here we combine zircon U–Pb geochronology with zircon trace element geochemistry of intrusive rocks associated with the Candelaria deposit, one of the world’s largest IOCG deposits, to unravel distinctive signatures diagnostic of magmatic fertility. Our results reveal a marked transition in the geochemistry of intrusions in the Candelaria district, characterized by changes in the redox state, water content and temperature of magmas over time. The oldest magmatic stage (~ 128–125 Ma), prior to the formation of the Candelaria deposit, was characterized by zircon Eu/Eu* ratios of 0.20–0.42, and redox conditions of ΔFMQ − 0.4 to + 1.0. The earliest magmatic stage related to the formation of Fe-rich mineralization at Candelaria (118–115 Ma) exhibits low zircon Eu/Eu* ratios (0.09–0.18), low oxygen fugacity values (ΔFMQ ~− 1.8 to + 0.2) and relatively high crystallization temperatures. In contrast, the youngest stage at ~ 111–108 Ma shows higher zircon Eu/Eu* (~ 0.37–0.69), higher oxygen fugacity values (ΔFMQ ~ + 0.4 to + 1.3) and a decrease in crystallization temperatures, conditions that are favorable for the transport and precipitation of sulfur and chalcophile elements. We conclude that Candelaria was formed through two distinct ore-forming stages: the first associated with a reduced, high temperature, water-poor magma developed under a low tectonic stress, followed by a more oxidized, water-rich, and low temperature magmatic event related to a compressional regime. The first event led to Fe-rich and S-poor IOA-type mineralization, while the second event with geochemical signatures similar to those of porphyry copper systems, generated the Cu- and S-rich mineralization. This late stage overprinted preexisting IOA mineralization resulting in the formation of the giant Candelaria IOCG deposit.

Magnetically Active Bicontinuous Polymer Structures for Multiple Controlled Drug Delivery.

The targeted delivery of drugs using wireless navigable magnetic robots, allows the delivery of drug molecules to be controlled non only in time but also in space, improving medical outcomes. The main disadvantages behind their use lies in the low amount of drug that can be transported and the single nature of drug that can be loaded (hydrophilic or hydrophobic). These considerations limit their use in co-delivery systems, now recognized to be very promising for many different pathologies. We developed a magnetic bijel-like structure to load and release different types of molecules (hydrophilic and hydrophobic). In this work, we explored the use of ε-caprolactone, which can polymerize, forming hydrophobic domains (oil phase). After mixing with iron oxide nanoparticles (NPs), the water dispersion creates a magnetic biphasic porous structure without phase separation. The resulting device showed good performance both in magnetic actuation and as a drug delivery system. This article is protected by copyright. All rights reserved.

A Deep Learning Approach for Chromium Detection and Characterization from Soil Hyperspectral Data

High levels of chromium (Cr) in soil pose a significant threat to both humans and the environment. Laboratory-based chemical analysis methods for Cr are time consuming and expensive; thus, there is an urgent need for a more efficient method for detecting Cr in soil. In this study, a deep neural network (DNN) approach was applied to the Land Use and Cover Area frame Survey (LUCAS) dataset to develop a hyperspectral soil Cr content prediction model with good generalizability and accuracy. The optimal DNN model was constructed by optimizing the spectral preprocessing methods and DNN hyperparameters, which achieved good predictive performance for Cr detection, with a correlation coefficient value of 0.79 on the testing set. Four important hyperspectral bands with strong Cr sensitivity (400–439, 1364–1422, 1862–1934, and 2158–2499 nm) were identified by permutation importance and local interpretable model-agnostic explanations. Soil iron oxide and clay mineral content were found to be important factors influencing soil Cr content. The findings of this study provide a feasible method for rapidly determining soil Cr content from hyperspectral data, which can be further refined and applied to large-scale Cr detection in the future.

Green synthesis and optimization of iron oxide nanoparticles as MRI contrast agent

Iron nanoparticles (FeNPs) derived from herbal plants are being explored as potential magnetic resonance imaging (MRI) contrast agents due to their biocompatibility and ability to perform targeted drug delivery. For the first time, the usage of various novel combinations of leaf extracts such as those of Azadirachta indica and Piper betle and extracts of two other Ayurvedic herbs – namely, Asparagus racemosus and Symplocos – was attempted for eco-friendly green synthesis of FeNPs. The nanoparticles were coated onto nanofibers made from a banana pseudo-stem (FENPs-NF) to enhance their biocompatibility. The synthesis process was optimized using response surface methodology, and techniques such as ultraviolet–visible (UV–Vis) spectroscopy, vibrating-sample magnetometry, atomic absorption spectroscopy (AAS), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT-IR) were used for characterization. Hemolytic and immune cell assays, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and MRI analysis were carried out. A peak at 325 nm observed in UV–Vis spectroscopy, AAS, FE-SEM, EDX and FT-IR proved the presence of FeNPs. Hemolytic and immune cell assays indicated biocompatibility, and the MTT assay (MCF-7) showed inhibition at 250 μg/ml. FeNPs and FeNPs-NF showed a good signal loss in MRI analysis at 1.5 T, proving their contrast agent nature. Thus, FeNPs synthesized from herbal plant sources may open a new door for potential application in the biomedical field as a chemical-free and biocompatible MRI contrast agent.

Microbial community response to hydrocarbon exposure in iron oxide mats: an environmental study

Hydrocarbon pollution is a widespread issue in both groundwater and surface-water systems; however, research on remediation at the interface of these two systems is limited. This interface is the oxic–anoxic boundary, where hydrocarbon pollutant from contaminated groundwaters flows into surface waters and iron mats are formed by microaerophilic iron-oxidizing bacteria. Iron mats are highly chemically adsorptive and host a diverse community of microbes. To elucidate the effect of hydrocarbon exposure on iron mat geochemistry and microbial community structure and function, we sampled iron mats both upstream and downstream from a leaking underground storage tank. Hydrocarbon-exposed iron mats had significantly higher concentrations of oxidized iron and significantly lower dissolved organic carbon and total dissolved phosphate than unexposed iron mats. A strong negative correlation between dissolved phosphate and benzene was observed in the hydrocarbon-exposed iron mats and water samples. There were positive correlations between iron and other hydrocarbons with benzene in the hydrocarbon-exposed iron mats, which was unique from water samples. The hydrocarbon-exposed iron mats represented two types, flocculent and seep, which had significantly different concentrations of iron, hydrocarbons, and phosphate, indicating that iron mat is also an important context in studies of freshwater mats. Using constrained ordination, we found the best predictors for community structure to be dissolved oxygen, pH, and benzene. Alpha diversity and evenness were significantly lower in hydrocarbon-exposed iron mats than unexposed mats. Using 16S rDNA amplicon sequences, we found evidence of three putative nitrate-reducing iron-oxidizing taxa in microaerophile-dominated iron mats (Azospira, Paracoccus, and Thermomonas). 16S rDNA amplicons also indicated the presence of taxa that are associated with hydrocarbon degradation. Benzene remediation-associated genes were found using metagenomic analysis both in exposed and unexposed iron mats. Furthermore, the results indicated that season (summer vs. spring) exacerbates the negative effect of hydrocarbon exposure on community diversity and evenness and led to the increased abundance of numerous OTUs. This study represents the first of its kind to attempt to understand how contaminant exposure, specifically hydrocarbons, influences the geochemistry and microbial community of freshwater iron mats and further develops our understanding of hydrocarbon remediation at the land–water interface.

Magnetic iron oxide nanoparticle enhanced microwave pretreatment for anaerobic digestion of meat industry sludge

Our study investigates the effects of iron oxide (Fe3O4) nanoparticles combined microwave pretreatment on the anaerobic digestibility and soluble chemical oxygen demand (SCOD) of meat industry sludge. One of our main objectives was to see whether the different microwave-based pretreatment procedures can enhance biogas production by improving the biological availability of organic compounds. Results demonstrated that combining microwave irradiation with magnetic iron oxide nanoparticles considerably increased SCOD (enhancement ratio was above 1.5), the rate of specific biogas production, and the total cumulative specific biogas volume (more than a threefold increment), while having no negative effect on the biomethane content. Furthermore, the assessment of the sludge samples’ dielectric properties (dielectric constant and loss factor measured at the frequency of 500 MHz) showed a strong correlation with SCOD changes (r = 0.9942, R2 = 0.99), offering a novel method to evaluate pretreatment efficiency.

Dual ionotropic crosslinked biopolymer magnetic nanocomposites as 5‐Fluorouracil nanocarrier for potential colorectal cancer treatment

AbstractThis study aimed to synthesize dual‐crosslinked chitosan‐alginate nanocomposites (Cs‐Alg/IO NCs) using green‐synthesized iron oxide nanoparticles (IO, Fe3O4 NPs) for drug delivery application. The NCs, formed via ionotropic gelation with sodium tripolyphosphate (TPP) and calcium chloride (CaCl2) as crosslinking agents for Cs and Alg, respectively, and further characterized for physiochemical properties. The presence of Fe3O4 NPs and 5‐Fluorouracil (5FU) increased hydrodynamic size (153.12 ± 0.57 to 207.64 ± 3.59 nm). Morphological studies revealed NC agglomeration within nanoscales. 5FU‐loaded Cs‐Alg/IO NCs (Cs‐Alg/IO 5FU NCs) exhibited superparamagnetic behavior and sustained drug release under various pH conditions. Cytotoxicity assays on colon cancer cells (HCT116 and HT‐29) and normal colon cells (CCD‐112) indicated higher cancer cell selectivity (selectivity index, SI = 1.91) in 2D models. Elevated IC50 values in 3D models were linked to lower drug loading capacity (LC) and encapsulation efficiency (EE). Overall, the study highlights the potential of dual‐crosslinked biopolymer NCs with green‐synthesized Fe3O4 NPs for developing an anticancer drug delivery system in colorectal cancer treatment.Highlights Synthesis of 5FU‐loaded dual crosslinked Cs‐Alg/IO NCs and Cs‐Alg IPN. Physicochemical characterization of cross‐linked magnetic nanocarriers. Investigation of sustained drug release using superparamagnetic nanocarriers. Evaluation of selective cytotoxicity for Cs‐Alg/IO 5FU NCs.