Formation Of Magnetite Nanoparticles Research Articles

Biomimetic Approach for Sustainable Magnetite Nanoparticle Synthesis Using Polycations

AbstractMagnetotactic bacteria produce magnetite nanoparticles called magnetosomes at ambient conditions via a protein‐stabilized transient amorphous precursor to obtain precise control over particle size and morphology. In a bioinspired approach, such biomineralization processes are emulated, mimicking proteins involved in magnetosome formation using the positively charged analog poly‐L‐arginine. While the additive is expensive, it remains elusive whether the change in magnetite formation mechanism arises solely from the polymer's cationic nature. This study uses different mass‐produced and sustainably sourced polycations to induce the biomineralization‐reminiscent formation of magnetite nanoparticles. These findings present how to achieve control over nanoparticle size (from 10 to 159 nm) and morphology (compact and sub‐structured) as well as magnetic properties (superparamagnetic, stable‐single‐domain, vortex state) at ambient temperature and pressure using these additives. Furthermore, the formation of large nanoparticles with the addition of poly(diallyldimethylammonium chloride) (PDADMAC) at low alkalinity highlights how magnetotactic bacteria may produce magnetite nanoparticles under similar conditions. Confirming the polycations' ability to electrostatic stabilize amorphous ferrihydrite, it is anticipated that parametric in vitro studies on polymer properties will provide valuable insights into magnetite biomineralization and aid in rationally designing magnetic nanomaterials.

Chemical activation and magnetization of onion waste derived carbon for arsenic removal

Arsenic is a known human carcinogen and its contamination of drinking water has been a global challenge. In this study, magnetic activated carbon (MAC) as an efficient adsorbent material was synthesized by hydrothermal method. Three adsorbent materials MCH, MCH3 and MCNa were synthesized using different chemical activators like HNO3, H3PO4 and NaOH respectively. Structural and morphological features of the adsorbents before and after magnetization were determined by XRD, FTIR, FESEM, EDX and TGA. BJH nitrogen adsorption–desorption isotherm was used to find the surface area and pore size of adsorbents while the surface charge was determined by measuring zeta potential. FESEM images clearly showed the incorporation of magnetite nanoparticles into a porous network. The XRD further confirmed the formation of magnetite nanoparticles within the network of porous carbon with average crystallite sizes of 6.3, 5.8, 5.5 nm for MCH, MCH3 and MCNa respectively. To examine the adsorption behaviour of As(III) onto the MAC, batch adsorption experiments were conducted with the effect of different parameters like initial concentration, temperature, time, amount of adsorbent and pH. The results showed that MCNa is a potential adsorbent for As(III) with removal efficiency of 99%. Overall adsorption process follows pseudo 2nd order kinetics while the Langmuir model was found well applicable to the experimental data. Thermodynamics of adsorption and desorption studies suggest that chemisorption is a predominant adsorption mechanism. Cost-effectiveness, novelty and magnetic recovery are the key features making onion-based MAC a potential adsorbent for the removal of As(III) from contaminated water.

Hydrogenation of CO in the Presence of Fe-Containing Materials Based on Carbon Supports

Hydrothermal carbonization of lignin was used to prepare a precursor of a carbon-containing support to obtain supported iron-containing catalysts for the hydrogenation of carbon monoxide. In the paper, the possibility of forming a carbon support prone to the deposition of metal ions was investigated. Deep structural transformations occurring in the polymer matrix of lignin were demonstrated by FTIR spectroscopy. The thermal stability of the support material was determined by thermal analysis in the region up to 400 °C. The formation of magnetite nanoparticles with a size of about 7‒8 nm at the stage of preliminary calcination of the metal-carbon system was shown by X-ray diffraction analysis (XRD). It was found that the resulting systems have high activity comparable to the activity of the system based on activated carbon: the conversion of carbon monoxide reached 98%, the yield of C5+ hydrocarbons reached 72 g/m3.

Larger pores dramatically enhance activity of an immobilized enzyme in mesoporous magnetic silica

Here, we report the influence of the pore size in biocatalysts based on magnetically responsive mesoporous silicas on the loading of an immobilized enzyme - glucose oxidase (GOx) - and the activity and reusability of the biocatalyst in d-glucose oxidation. The choice of the silica supports was determined by their commercial availability and drastically different pores sizes: 6 nm and 15 nm. In the former case, the pores are too small to accommodate GOx whose hydrodynamic diameter is 7.6 nm, while in the latter case, there is an ample room for immobilization of GOx inside the pores. Magnetic properties in both cases were imparted by the formation of magnetite nanoparticles in silica pores, whose presence did not alter the pore size distribution. We demonstrate that larger pores allow for higher enzyme loading capacity due to immobilization inside the pores, remarkable 100% relative activity, and enhanced stability in the repeated use due the conformational integrity of GOx in spacious pores. This study unambiguously shows advantages of supports with pores larger than the size of an enzyme for its immobilization in the biocatalyst synthesis.

Heavy metal and organic dye removal via a hybrid porous hexagonal boron nitride-based magnetic aerogel

Numerous adsorbents have been introduced to efficiently remove heavy metals and organic dyes from environmental water samples. However, magnetic a porous network aerogels are rarely developed to capture inorganic and organic pollutants from aqueous. We herein fabricated hexagonal boron nitride nanosheets (h-BNNSs)-based on magnetic hybrid aerogels (MHAs) as a lightweight adsorbent for robust uptake of Cr(VI), As(V), methylene blue (MB) and acid orange (AO). The synthetic procedure of poly(ethyleneimine)-modified h-BNNSs (PEI-h-BNNSs) involved thermal poly condensation of melamine and boric acid, pyrolysis of the resultant products which allowed exfoliated by ultra-sonication process further functionalization with PEI-mediated modification of h-BNNSs. The as formed PEI-h-BNNSs allowed in-situ formation of magnetite nanoparticles (Fe3O4 NPs) decorated on their surfaces, which are turned to be PEI-h-BNNSs@Fe3O4 NPs. The lyophilization treatment of PEI-h-BNNSs@Fe3O4 NPs-loaded PVA hydrogels generated the MHAs with large porous structures, diverse and numerous functional groups, good super-paramagnetic and a zero net surface charge. These features enabled the proposed adsorbent (MHAs) to be utilized to efficiently remove Cr(VI), As(V), MB, and AO from an aqueous solution, with maximum adsorption capacity estimated to be 833, 426, 415, 286 mg g−1, respectively. The adsorption kinetics and isotherm data demonstrated that MHAs mediated adsorption of Cr(VI), As(V), MB and AO followed the Freundlich isotherm model and a pseudo-second-order kinetics model. This finding signifies that the MHAs exhibit heterogeneous binding behavior with multilayer chemisorption of Cr(VI), As(V), MB and AO. Subsequently, the practical application were validated by conducting their detoxification of chromium and arsenic in soli-sludge samples.

Self-assembly of ferria – nanocellulose composite fibres

An environmentally benign synthesis of a magnetically responsive carboxymethylated cellulose nanofibril-based material is reported. Applied experimental conditions lead to the in-situ formation of magnetite nanoparticles with primary particle sizes of 2.0–4.0 nm or secondary particles of 3.6–16.4 nm depending on whether nucleation occurred between individual carboxymethylated cellulose nanofibrils, or on exposed fibril surfaces. The increase in magnetite particle size on the cellulose fibril surfaces was attributed to Ostwald ripening, while the small particles formed within the carboxymethyl cellulose aggregates were presumably due to steric interactions. The magnetite nanoparticles were capable of coordinating to carboxymethylated cellulose nanofibrils to form large “fibre-like” assemblies. The confinement of small particles within aggregates of reductive cellulose molecules was most likely responsible for excellent conservation of magnetic characteristics on storage of this material. The possibility for using the material in drug delivery applications with release rate controlled by daylight illumination is presented.

Magnetite nanoparticles synthesized using grape fruit extract: synthesis, morphology, hyperthermia application and catalytic activity in hydrogen peroxide decomposition

The paper presents a simple one-step "green" approach to the synthesis of magnetite nanoparticles. The magnetite nanoparticles were synthesized using fruit extract obtained from grape peels and grape pulp. The formation of magnetite nanoparticles was confirmed by X-ray diffraction analysis (XRD), infrared spectroscopy (IR), Mössbauer spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The crystallites sizes of magnetite nanoparticles are 7 and 14 nm for Fe3O4-peel and Fe3O4-pulp samples, respectively. Scanning electron microscopy images show that the samples consist of agglomerated nanoparticles. The synthesized magnetite nanoparticles showed good prospects for their use in magnetic hyperthermia. SAR values ​​of 0.488 W/g and 1.330 W/g for Fe3O4-peel and Fe3O4-pulp samples, respectively. The synthesized magnetic nanoparticles show excellent colloidal stability in the aqueous solutions. The maximum hyperthermia temperatures are 42.28 °C and 42.48 °C for Fe3O4-peel and Fe3O4-pulp samples, respectively. Studies of the catalytic activity of magnetite were performed in decomposition of hydrogen peroxide in a batch mode. The degrees of H2O2 decomposition are 67.5% and 65.25% for the Fe3O4-peel and Fe3O4-pulp samples respectively. The high catalytic activity of the synthesized samples makes them promising candidates for the decomposition of hydrogen peroxide in wastewater disinfection.

Facile synthesis, characterization of various polymer immobilized on magnetite nanoparticles applying the coprecipitation method

AbstractIn this study, systematic examination of the effect of different polymer types (functional groups) on the one‐step synthesis of polymer immobilized magnetite nanoparticle via the modified coprecipitation method was carried out. By using five different polymers with different functional groups of polyacrylic acid (PAA), polyacrylamide (PAM), polyethylene glycol (PEG), polyethylene imine (PEI), and polyvinyl alcohol (PVA), the effect of the polymer difference on magnetite nanoparticle formation, polymer immobilization, composite particle size, zeta potential and magnetic properties of the resulting composite were measured in detail. The results show that the immobilized polymer yield varied significantly depending on the type of polymer used and their order was as follows; PEG < PEI < PAM < PAA < PVA. Despite the simple method, PVA/MNP achieved high immobilized polymer amount of 0.2 g/(g‐Fe3O4), which was about 1.8 times larger than that prepared by a conventional method. Furthermore, the different zeta potentials and hydrodynamic diameter corresponding to each functional group of the immobilized polymer were observed. The results of the vibrating sample magnetometer (VSM) measurement confirmed that all the polymer/MNP composites showed a superparamagnetic behavior. These results showed that the proposed method is very simple, facile, and applicable to various polymers to synthesize polymer immobilized on magnetite nanoparticle.

Wettability of Magnetite Nanoparticles Guides Growth from Stabilized Amorphous Ferrihydrite.

Crystal formation via amorphous precursors is a long-sought-after gateway to engineer nanoparticles with well-controlled size and morphology. Biomineralizing organisms, like magnetotactic bacteria, follow such a nonclassical crystallization pathway to produce magnetite nanoparticles with sophistication unmatched by synthetic efforts at ambient conditions. Here, using in situ small-angle X-ray scattering, we demonstrate how the addition of poly(arginine) in the synthetic formation of magnetite nanoparticles induces a biomineralization-reminiscent pathway. The addition of poly(arginine) stabilizes an amorphous ferrihydrite precursor, shifting the magnetite formation pathway from thermodynamic to kinetic control. Altering the energetic landscape of magnetite formation by catalyzing the pH-dependent precursor attachment, we tune magnetite nanoparticle size continuously, exceeding sizes observed in magnetotactic bacteria. This mechanistic shift we uncover here further allows for crystal morphology control by adjusting the pH-dependent interfacial interaction between liquidlike ferrihydrite and nascent magnetite nanoparticles, establishing a new strategy to control nanoparticle morphology. Synthesizing compact single crystals at wetting conditions and unique semicontinuous single-crystalline nanoparticles at dewetting conditions in combination with an improved control over magnetite crystallite size, we demonstrate the versatility of bio-inspired, kinetically controlled nanoparticle formation pathways.

Steering the synthesis of Fe3O4 nanoparticles under sonication by using a fractional factorial design

Superparamagnetic iron oxide nanoparticles (MNPs) have the potential to act as heat sources in magnetic hyperthermia. The key parameter for this application is the specific absorption rate (SAR), which must be as large as possible in order to optimize the hyperthermia treatment. We applied a Plackett-Burman fractional factorial design to investigate the effect of total iron concentration, ammonia concentration, reaction temperature, sonication time and percentage of ethanol in the aqueous media on the properties of iron oxide MNPs. Characterization techniques included total iron content, Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, High Resolution Transmission Electron Microscopy, and Dynamic Magnetization. The reaction pathway in the coprecipitation reaction depended on the initial Fe concentration. Samples synthesized from 0.220 mol L−1 Fe yielded magnetite and metastable precipitates of iron oxyhydroxides. An initial solution made up of 0.110 mol L−1 total Fe and either 0.90 or 1.20 mol L−1 NH3(aq) led to the formation of magnetite nanoparticles. Sonication of the reaction media promoted a phase transformation of metastable oxyhydroxides to crystalline magnetite, the development of crystallinity, and the increase of specific absorption rate under dynamic magnetization.

A novel direct method in one-step for catalytic heavy crude oil upgrading using iron oxide nanoparticles

We proposed a direct in situ synthesis method for iron oxide nanoparticles (NPs) along with catalytic erformance upgrading of heavy crude oil (HCO). Our method compares the upgrading of a HCO where other iron oxide nanoparticles were synthesized by a traditional thermal decomposition method of organometallic compounds in the presence of stabilizing agents and solvents of high boiling points. Furthermore, the in situ nanoparticles were extensively characterized by XRD, Mössbauer spectroscopy and TEM microscopy which confirmed the presence of magnetite and akaganeite phases, with an average diameter of 20−43 nm. Nanoparticles by thermal decomposition method were investigated by XRD, UHR-FE-SEM and HRTEM and showed the formation of magnetite nanoparticles with an average diameter of 6.7 ± 1.4 nm. Subsequently, the nanoparticles were evaluated in a batch reactor using HCO from the Golden Lane of Mexico at 44.1 bar (initial H2 pressure) and 380 °C, for 1 h at 500 rpm. It was observed that, even under hydrogen limited conditions, there are better physicochemical properties in terms of viscosity, API gravity and heavy fractions decrease, for example, the residue conversion was about 20 % and the kinetic model was adjusted to a five lump model. The formation of the iron sulfide phase (FeS) was detected during the analysis of the spent catalyst.

A facile, two-step synthesis and characterization of Fe 3 O 4 -L Cysteine -graphene quantum dots as a multifunctional nanocomposite.

In this research, a facile, two-step synthesis of Fe3O4–LCysteine–graphene quantum dots (GQDs) nanocomposite is reported. This synthesis method comprises the preparation of GQDs via hydrothermal route, which should be conjugated to the LCysteine functionalized core–shell magnetic structure with the core of about 7.5-nm iron oxide nanoparticle and 3.5-nm LCysteine shell. LCysteine, as a biocompatible natural amino acid, was used to link magnetite nanoparticles (MNPs) with GQDs. X-ray powder diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray were used to investigate the presence and formation of MNPs, {text{L}}_{{{text{Cysteine}}}} functionalized MNPs, and final hybrid nanostructure. Morphology and size distribution of nanoparticles were demonstrated by scanning electron microscopy and transmission electron microscopy. Finally, the magnetic and optical properties of the prepared nanocomposite were measured by vibrating sample magnetometer, ultraviolet–visible, and photoluminescence spectroscopy. The results show that Fe3O4–LCysteine–GQDs nanocomposite exhibits a superparamagnetic behavior at room temperature with high saturation magnetization and low magnetic coercivity, which are 28.99 emu/g and 0.09 Oe, respectively. This nanocomposite also shows strong and stable emission at 460 nm and 530 nm when it is excited with the 235 nm wavelength. The magnetic GQDs structure also reveals the absorption wavelength at 270 nm. Therefore, Fe3O4–LCysteine–GQDs nanocomposite can be considered as a potential multifunctional hybrid structure with magnetic and optical properties simultaneously. This nanocomposite can be used for a wide range of biomedical applications like magnetic resonance imaging (MRI) contrast agents, biosensors, photothermal therapy, and hyperthermia.

An innovative data processing method for studying nanoparticle formation in droplet microfluidics using X-rays scattering.

X-ray scattering techniques provide a powerful means of characterizing the formation of nanoparticles in solution. Coupling these techniques to segmented-flow microfluidic devices that offer well-defined environments gives access to in situ time-resolved analysis, excellent reproducibility, and eliminates potential radiation damage. However, analysis of the resulting datasets can be extremely time-consuming, where these comprise frames corresponding to the droplets alone, the continuous phase alone, and to both at their interface. We here describe a robust, low-cost, and versatile droplet microfluidics device and use it to study the formation of magnetite nanoparticles with simultaneous synchrotron SAXS and WAXS. Lateral outlet capillaries facilitate the X-ray analysis and reaction times of between a few seconds and minutes can be accommodated. A two-step data processing method is then described that exploits the unique WAXS signatures of the droplets, continuous phase, and interfacial region to identify the frames corresponding to the droplets. These are then sorted, and the background scattering is subtracted using an automated frame-by-frame approach, allowing the signal from the nanoparticles to be isolated from the raw data. Modeling these data gives quantitative information about the evolution of the sizes and structures of the nanoparticles, in agreement with TEM observations. This versatile platform can be readily employed to study a wide range of dynamic processes in heterogeneous systems.

Ultrasound aided heterogeneous Fenton degradation of Acid Blue 15 over green synthesized magnetite nanoparticles

Magnetite nanoparticles were synthesized by bio-reduction method using neem leaf extract and its structural, morphological, chemical and magnetic characteristics were examined. The characteristic peaks obtained at 30.17°, 35.62°, 43.22°, 53.73°, 57.16° and 62.87° in the X-ray diffraction pattern (XRD) confirmed the formation of magnetite nanoparticles. Batch experiments were conducted to examine the efficiency of magnetite nanoparticles for degradation of the dye, Acid Blue 15 (AB15) by Fenton and ultrasound aided Fenton process. The results revealed enhanced dye removal in ultrasound aided Fenton mode when compared to Fenton process as degradation was attained within 20 min of contact time in the former process. Further, operational parameters on ultrasound aided Fenton degradation of AB 15 were optimized. Total organic carbon (TOC) removal efficiency and dye removal efficiency obtained was 40.4% and 99.3%, respectively at an optimum condition of pH 3, catalyst dosage 1 g L-1, H2O2 dosage 10 mM, and initial AB15 dye concentration of 100 mg L-1. Leached iron concentration at the end of the reaction was determined to be 0.60 mg L-1. The catalyst possesses good stability as it exhibited good performance over 3 cycles. The involvement of hydroxyl radicals in the degradation was confirmed by conducting experiments using radical scavengers. Gas chromatography mass spectrum (GC–MS) analysis revealed the formation of 4-((4-ammoniocyclohexa-2,5-dien-1-ylidene)(phenyl)methyl)aniline, N-ethyl-N-methylethanamine and 3- methylbenzenesulfonate as by-products of ultrasound aided Fenton process. Hence, ultrasound aided Fenton process is a promising method to degrade organic pollutants in wastewater.

Solvothermal‐assisted green synthesis of hybrid Chi‐Fe3O4nanocomposites: a potential antibacterial and antibiofilm material

In this present study, a hybrid Chi-Fe3O4 was prepared, characterised and evaluated for its antibacterial and antibiofilm potential against Staphylococcus aureus and Staphylococcus marcescens bacterial pathogens. Intense peak around 260 nm in the ultraviolet-visible spectrum specify the formation of magnetite nanoparticles. Spherical-shaped particles with less agglomeration and particle size distribution of 3.78-46.40 nm were observed using transmission electron microscopy analysis and strong interaction of chitosan with the surface of magnetite nanoparticles was studied using field emission scanning microscopy (FESEM). X-ray diffraction analysis exhibited the polycrystalline and spinel structure configuration of the nanocomposite. Presence of Fe and O, C and Cl elements were confirmed using energy dispersive X-ray microanalysis. Fourier transform infrared spectroscopic analysis showed the reduction and formation of Chi-Fe3O4 nanocomposite. The antibacterial activity by deformation of the bacterial cell walls on treatment with Chi-Fe3O4 nanocomposite and its interaction was visualised using FESEM and the antibiofilm activity was determined using antibiofilm assay. In conclusion, this present study shows the green synthesis of Chi-Fe3O4 nanocomposite and evaluation of its antibacterial and antibiofilm potential, proving its significance in medical and biological applications.

Synthesis of diglycolic acid functionalized core-shell silica coated Fe3O4 nanomaterials for magnetic extraction of Pb(II) and Cr(VI) ions

Amine-terminated core-shell silica coated magnetite nanoparticles were functionalized with diglycolic acid for the first time to create acid moiety on the surface of the nanoparticles. The formation of magnetite nanoparticles was scrutinised through XRD, SEM, EDS, TEM, VSM and FTIR spectroscopy. The BET surface area of nano-sorbent was found to be 4.04 m2/g with pore size 23.68 nm. These nanomaterials were then utilized to remove the Pb(II) and Cr(VI) ions from their aqueous media and uptake of metal ions was determined by atomic absorption spectroscopy (AAS). A batch adsorption technique was applied to remove both ions at optimised pH and contact time with maximum adsorption efficiency for Pb(II) ions at pH 7 while for Cr(VI) ions at pH 3. Adsorption mechanism was studied using Langmuir and Freundlich isotherms and equilibrium data fitted well for both the isotherms, showing complex nature of adsorption comprising both chemisorption as well as physio-sorption phenomena. The nanosorbents exhibited facile separation by applying external magnetic field due to the ferrimagnetic behaviour with 31.65 emu/g saturation magnetization. These nanosorbents were also found to be used multiple times after regeneration.

Superparamagnetic polyacrylamide/magnetite composite gels

Superparamagnetic gels based on polyacrylamide and magnetite were synthesized by the in situ preparation of magnetite nanoparticles in polyacrylamide (PAM) physical hydrogels at different polymer concentrations. The formation of magnetite nanoparticles and their magnetic properties were characterized by Fourier transform infrared (FTIR) spectroscopy, rheometry, X-ray diffractometry (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). FTIR spectroscopy showed that all composite gels had features related to pure PAM. The structural characterization by Rietveld method revealed an average crystallite size below 18 nm and SEM micrographs of the gel with Fe3O4 showed that the particles have spherical structures. The rheology-related measurements indicated that the gels had a strong pseudoplastic character. Magnetic measurements confirmed the superparamagnetic behavior of the obtained magnetite nanoparticles, both in the form of pure powder and within PAM gel matrix. Magnetite crystallite size decreased as PAM content was increased, which was explained as a function of thermodynamic and kinetic effects.

Novel monopolar arrangement of multiple iron electrodes for the large-scale production of magnetite nanoparticles for electrochemical reactors

High-purity magnetite nanoparticles with a mixed quasi-spherical and cubic morphology have been successfully synthesized using a new alternating monopolar arrangement of multiple iron electrodes in water. The magnetite nanoparticles have a narrow size distribution with a mean size ranging from 20 to 30 nm, depending on the applied voltage and pH. The formation of magnetite nanoparticles is favored only in the pH range of 7–10; outside this range, magnetite nanoparticles cannot be produced. The magnetite nanoparticles exhibit ferromagnetic properties with saturation magnetization ranging from 16 to 75 emu/g. They demonstrated to be a promising electrocatalyst for oxygen reduction reactions in basic media. This facile method is a promising production route for magnetite nanoparticles and can be easily scaled up for large production.

New Smart Magnetic Ionic Liquid Nanocomposites Based on Chemically Bonded Imidazole Silica for Water Treatment.

New magnetic silica imidazolium ionic liquid nanocomposites were synthesized by a sol–gel technique. The (3-aminopropyl)triethoxysilane (APTS) was condensed with glyoxal and p-hydroxybenzaldehyde in acetic acid to produce an amino-modified silica ionic liquid (Si-IIL). The APTS was condensed with TEOS in ethanol and water to prepare amino-modified SiO2 nanoparticles. The produced amino-modified SiO2 silica was condensed with glyoxal and p-hydroxybenzaldehyde in acetic acid to produce chemically bonded silica SiO2-IIL. The SiO2-IIL and Si-IIL were used as capping agents during and after the formation of magnetite nanoparticles in ammonia to produce magnetic SiO2-IIL-Fe3O4 and Fe3O4-Si-IIL adsorbents, respectively. Their chemical structure, morphology, crystalline lattice structure, surface charges, particle sizes, and magnetic characteristics elucidated the formation of core–shell and highly dispersed magnetic nanocomposites. The saturation magnetization values of Fe3O4-Si-IIL and SiO2-IIL-Fe3O4 were 35.3 and 30.8, respectively. The uniform dispersed disconnected spherical morphologies appeared for Fe3O4-Si-IIL hybrid and the core–shell spherical morphology obtained with SiO2-IIL-Fe3O4 hybrid NPs. The Fe3O4-Si-IIL and SiO2-IIL-Fe3O4 show an excellent high chemical adsorption capacities as 460.3 and 300.9 mg·g–1, respectively (not reported in the literature) when used as an adsorbent to remove CB-R250 water pollutant under optimum conditions. Their applicability and reusability as fast and highly effective adsorbents for Coomassie blue (CB-R250) organic water pollutants were investigated.

Decoding Biomineralization: Interaction of a Mad10-Derived Peptide with Magnetite Thin Films.

Protein-surface interactions play a pivotal role in processes as diverse as biomineralization, biofouling, and the cellular response to medical implants. In biomineralization processes, biomacromolecules control mineral deposition and architecture via complex and often unknown mechanisms. For studying these mechanisms, the formation of magnetite nanoparticles in magnetotactic bacteria has become an excellent model system. Most interestingly, nanoparticle morphologies have been discovered that defy crystallographic rules (e.g., in the species Desulfamplus magnetovallimortis strain BW-1). In certain conditions, this strain mineralizes bullet-shaped magnetite nanoparticles, which exhibit defined (111) crystal faces and are elongated along the [100] direction. We hypothesize that surface-specific protein interactions break the nanoparticle symmetry, inhibiting the growth of certain crystal faces and thereby favoring the growth of others. Screening the genome of BW-1, we identified Mad10 (Magnetosome-associated deep-branching) as a potential magnetite-binding protein. Using atomic force microscope (AFM)-based single-molecule force spectroscopy, we show that a Mad10-derived peptide, which represents the most conserved region of Mad10, binds strongly to (100)- and (111)-oriented single-crystalline magnetite thin films. The peptide-magnetite interaction is thus material- but not crystal-face-specific. It is characterized by broad rupture force distributions that do not depend on the retraction speed of the AFM cantilever. To account for these experimental findings, we introduce a three-state model that incorporates fast rebinding. The model suggests that the peptide-surface interaction is strong in the absence of load, which is a direct result of this fast rebinding process. Overall, our study sheds light on the kinetic nature of peptide-surface interactions and introduces a new magnetite-binding peptide with potential use as a functional coating for magnetite nanoparticles in biotechnological and biomedical applications.