Synthesis Of Magnetite Nanoparticles Research Articles

Synthesis, evaluation, and biocompatibility study of magnetite nano particles in normal cells and cancer cells for health care application

Magnetic nanoparticles have been synthesized in a very simple and economical way by the co-precipitation method, where the effect of molar concentrations of ferric chloride anhydrous (FeCl3) and iron (II) sulphate heptahydrate (FeSO4.7 H20) on magnetite synthesis has been investigated. Also, a detailed study was conducted to study the effect of magnetite and hematite on both normal and cancerous cell lines. After this, the magnetic nanoparticles obtained were analyzed by x-ray Diffraction (XRD), scanning electron microscope (SEM) - energy dispersive x-ray (EDX), Fourier transform infrared spectroscopy (FTIR), zeta potential, vibrating sample magnetometer (VSM), atomic force microscopy (AFM), MTT test, and cell apoptotic assay. The XRD peaks for magnetite were easily discernible in the final formulation. SEM images showed round particles in nano ranges, and FTIR peaks showed the presence of magnetite. Zeta potential showed surface charges. VSM showed the magnetic property of magnetite, and AFM confirmed SEM images. It can be concluded that magnetic nanoparticles were synthesized by the co-precipitation method using an optimized molar concentration of reagents. Also, the necessity of coating uncoated magnetic nanoparticles can be seen from the MTT assay. Cell apoptotic assays have shown that synthesized magnetite nanoparticles have shown potential apoptotic activity on cancer cell lines.

Preparation of magnetite nanoparticles and their application in the removal of methylene blue dye from wastewater

Wastewater is discharged in large amounts from different industries; thus, wastewater treatment is currently one of the main concerns, advanced oxidation is a promising technique for wastewater treatment. This research aims to synthesize magnetite nanoparticles and study their application in wastewater treatment via adsorption and advanced oxidation processes. Magnetite nanoparticles were synthesized via coprecipitation technique between ferric and ferrous sulfate at a molar ratio of 2:1. The prepared sample was characterized using FTIR, XRD, TEM, BET surface area, zeta potential, VSM, and UV‒visible spectroscopy. XRD confirmed the formation of a single face-centered cubic (FCC) spinel structure of Fe3O4. TEM revealed an average particle size of 29.2 nm and a BET surface area of 70.1 m2 g−1. UV‒visible spectroscopy revealed that the UV–visible peak of the sample was obtained at 410 nm. VSM confirmed the attraction of the sample to a magnet with a magnetization of 60 (emu/g). The removal efficiency of methylene blue was studied using adsorption and advanced oxidation methods. For adsorption, the studied parameters were dye concentration 2–10 ppm, 3–10 pH, and 50:300 mg Fe3O4/L. For advanced oxidation, peroxide was used with nanomagnetite as a catalyst, and the studied parameters were pH 2–11, magnetite dose 20–200 PPM, and peroxide dose 500–2000 PPM. The removal efficiency by adsorption reached 95.11% by adding 50 mg of Fe3O4/L and 10 ppm dye conc at 6.5 pH; on the other hand, in advanced oxidation, it reached 98.5% by adding 110 PPM magnetite and 2000 ppm H2O2 at pH 11. The magnetite nanoparticles were reused for ten cycles of advanced oxidation, for a 10% reduction in removal efficiency at the tenth cycle.

An electrochemical 3D platform using poly (alizarin red S) and magnetite nanoparticles for rapid recognition and determination of tryptophan enantiomers in whole blood samples

The construction of a simple and convenient electrochemical platform for the recognition of enantiomers is crucial for the life sciences and medical fields. Herein, a portable electrochemical 3D platform based on a carbon paste electrode modified (CPE) with poly (alizarin red S) (PARS) and magnetite nanoparticles (Fe3O4NPs) for the recognition and determination of tryptophan enantiomers from whole blood samples was developed. Several methods, including scanning electron microscopy (SEM), differential pulse voltammetry (DPV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), were used to evaluate the morphologies and electrochemical behaviors of the modified electrode. The synthesized magnetite nanoparticles are studied using SEM with energy-dispersive X-ray analysis (EDAX). Under the optimum experimental conditions, the current intensity ratio of d-Trp to l-Trp (ID/IL) was found to be 1.32 at PARS/Fe3O4NPs/CPE, according to the results of differential pulse voltammetry. Furthermore, the developed platform showed a good linear correlation between response current intensity and tryptophan enantiomer concentration, ranging from 0.001 to 0.2 mM. The detection limits for both d-Trp and l-Trp were found to be 0.3 µM. This study demonstrates that the designed platform is capable of rapidly detecting the enantiomeric ratio in a non-racemic tryptophan mixed solution. Finally, the proposed platform was used to identify the Trp enantiomers in human whole blood, confirming the effectiveness of the modified electrode in analyzing real samples. The electrochemical 3D platform is thus used not only to recognize tryptophan enantiomers but also exhibits a significant promise for practical uses.

Influence of temperature and stirring on the synthesis of magnetite nanoparticles

This study investigates the impact of temperature variations and stirring methods on the synthesis of magnetite nanoparticles. Conducted experiments employed a controlled precipitation method, with temperature ranges from 22 °C to 60 °C and four stirring methods, including magnetic stirring, sonication, vertical stirring, and vertical stirring combined with an ultrasonic bath. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and UV–Vis spectrophotometry. Results revealed significant influences of temperature and stirring on magnetite nanoparticles’ size, crystallinity, and optical properties. Elevated temperatures induced strain in the crystal lattice, resulting in a noisy signal, while the choice of stirring method influenced particle size stability. These findings offer valuable insights for optimizing synthesis conditions tailored to specific applications of magnetite nanoparticles, providing users with a better understanding of the factors influencing nanoparticle synthesis.

L-cysteine-coated magnetite nanoparticles as a platform for enzymes immobilization: Amplifying biocatalytic activity of Candida antarctica Lipase A

This study presents the synthesis of magnetite nanoparticles coated with L-cysteine (Fe3O4@LC) and their subsequent utilization as a support matrix for the immobilization of Candida antarctica Lipase A (CALA). The immobilization process involved physical interactions and covalent bonding mediated by glutaraldehyde. Comprehensive characterization was conducted using techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM), providing compelling evidence of a successful synthesis. Under optimized conditions, employing 1 mg of protein per gram of support, pH 7 in a 25 mM phosphate buffer, and a 5 h reaction at 25 °C, immobilization on glutaraldehyde-activated support achieved an impressive yield of 85.0 % ± 2.6, accompanied by a specific activity of 212.5 ± 1.3 U/g, outperforming the physical adsorption approach. Remarkably, the immobilized enzyme exhibited higher activity than the free enzyme at alkaline and acidic pH levels. Furthermore, thermal and pH inactivation studies revealed that the biocatalyst's half-life exceeded that of free CALA by more than 8 times at pH 10. These results underscore the potential of the Fe3O4@LC-GLU-CALA system as a robust biocatalytic matrix with promising applications in biodiesel production, ester synthesis, and pharmaceutical manufacturing.

Biogenic Synthesis of Magnetite Nanoparticles using the Roots of Mirabilis Jalapa for Efficient Removal of Eluent, Anti-Bacterial, and Antioxidant: A Sustainable Approach.

Magnetite nanoparticles hold quite immense applications in the fields of drug delivery, environmental remedies, and magnetic resonance imaging as they are biocompatible and can stabilize and reduce. An eco-friendly approach that is viable and sustainable for synthesizing magnetite nanoparticles with controlled properties has new avenues for their applications in various fields. Magnetite nanoparticles are often used in the removal of organic eluents as they can adsorb heavy metals which binds on the surface and cleans the polluted area. Magnetite nanoparticles synthesized from the roots of Mirabilis Jalapa have a variety of uses in the treatment of lesion infections. As antioxidants, they reduce the oxidative stress caused by free radicals. Morphology, size, and form of Magnetite nanoparticles are determined by UV-visible spectroscopy, SEM, EDX, TEM, TGA, XRD, and FTIR, respectively.

Plant-Mediated Synthesis of Magnetite Nanoparticles with Matricaria chamomilla Aqueous Extract.

Magnetite nanoparticles (NPs) possess properties that make them suitable for a wide range of applications. In recent years, interest in the synthesis of magnetite NPs and their surface functionalization has increased significantly, especially regarding their application in biomedicine such as for controlled and targeted drug delivery. There are several conventional methods for preparing magnetite NPs, all of which mostly utilize Fe(iii) and Fe(ii) salt precursors. In this study, we present a microwave hydrothermal synthesis for the precipitation of magnetite NPs at temperatures of 200 °C for 20 min and 260 °C for 5 min, with only iron(iii) as a precursor utilizing chamomile flower extract as a stabilizing, capping, and reducing agent. Products were characterized using FTIR, PXRD, SEM, and magnetometry. Our analysis revealed significant differences in the properties of magnetite NPs prepared with this approach, and the conventional two-precursor hydrothermal microwave method (sample MagH). FTIR and PXRD analyses confirmed coated magnetite particles. The temperature and magnetic-field dependence of magnetization indicate their superparamagnetic behavior. Importantly, the results of our study show the noticeable cytotoxicity of coated magnetite NPs-toxic to carcinoma cells but harmless to healthy cells-further emphasizing the potential of these NPs for biomedical applications.

Targeted Drug Delivery through the Synthesis of Magnetite Nanoparticle by Co-Precipitation Method and Creating a Silica Coating on it

Billions of dollars are spent annually in the world to treat and investigate problems caused by drug side effects. According to the estimation of health researchers, a huge part of people who take medicine suffer from complications caused by it. In this way, the necessity of using a targeted system in order to deliver medicine to the targeted place without damaging healthy tissues is felt more than before. In recent years, targeted drug delivery systems based on nanoparticles have received much attention. In the same direction, in this research, co-precipitation method was used to prepare magnetic nanoparticles using iron(|) and iron(||) oxides, and further, according to the synthesis steps of magnetite nanoparticles (MNPs) and the mechanism of formation and identification of magnetite nanoparticles ( Fe3O4) by examining the infrared pattern (FT-IR) obtained from Fe3O4 nanoparticles, the results of the magnetometric test (VSM) of Fe3O4 nanoparticles, X-ray diffraction pattern (XRD) of Fe3O4 nanoparticles, Field Emission Scanning Electron Microscope (FE-SEM) images obtained from Fe3O4 nanoparticles was discussed. After this stage, silica- coated iron nanoparticles (Fe3O4@SiO2) were prepared, and the infrared (FT-IR) pattern of Fe3O4@SiO2) was also investigated. It is worth mentioning that the mechanism of formation and identification of magnetic silica-coated iron nanoparticles (Fe3O4@SiO2) has been described in detail. Therefore, the obtained results indicate that the drug can be guided in a controlled and targeted manner by the magnetic field, and the results of the FE-SEM images show that the obtained product has a spherical morphology and the particle size distribution was less than 100 nm. Therefore, spherical shape and the symmetry of these particles can be helpful for their movement in the liquid mediu.

Facile green fabrication of magnetite nanoparticles using an aqueous flower extract of Murraya paniculata (L) Jack for an efficient removal of organic dye pollutant, antibacterial activities

This article reports, the plant-mediated synthesis of Magnetite nanoparticles achieved by utilising an aqueous flower extract of Murraya paniculata (L) Jack (FMPM NPs). The active compounds are phenols, alkaloids, flavones and terpenoids in the aqueous flower extract of Murraya paniculata act as ligating agents to synthesize novel green superparamagnetic magnetite nanoparticles by the coprecipitation method. As prepared FMPM NPs have been characterized by a range of spectroscopic and microscopic techniques. All spectroscopic and microscopic results confirmed the occurrence of pure FMPM NPs. Fourier transform-infrared spectroscopy (FTIR) shows the presence of a Fe-O bond and the band gap was found to be 2.57 eV for FMPM NPs. The surface area of the synthesized nanoparticles was 70.31 m2/g evaluated by BET analysis. The elemental analysis has been performed by the XPS technique. The XRD pattern revealed the crystal size of 14.12 nm of FMPM NPs. TEM images show the spherical shaped FMPM NPs with an average particle size of 11.58 nm. SEM results clearly show spherically shaped FMPM NPs. The superparamagnetic character of FMPM NPs is revealed by the VSM curve and saturation magnetization (Ms) value of 58 emu/g. FMPM NPs used for photocatalytic activity, tested against gram positive, gram negative and antifungal bacteria. As prepared FMPM NPs. showed 93 % removal efficiency of Fast sulphon black-F dye pollutant. Moreover, FMPM NPs efficiently inhibit the growth of Enterococcus faecalis and Penicillium chrysogenum. The current research is for the fabrication of magnetite nanoparticles utilising novel green source and examining their applications.

Cellulose esters: Synthesis for further formation of films with magnetite nanoparticles incorporated

This study investigated the homogeneous synthesis of cellulose acetate (CA) and propionate (CP) with varying degrees of substitution (DS) from sisal cellulose in a N, N-dimethylacetamide/lithium chloride (DMAc/LiCl) solvent system. These esters were used to prepare neat (CADSF/CPDSF) and nanocomposite films (CADSFFe/CPDSFFe) from prior synthesized magnetite nanoparticles (NPs, Fe3O4, 5.1 ± 0.5 nm). Among the CA and CP series, the composite CA0.7FFe and the neat CP0.7F films exhibited the highest modulus of elasticity, 2105 MPa and 2768 MPa, respectively, probably a consequence of the continuous fibrous structures present on the surface of these films. Microsphere formation on the film's surface was observed in scanning electron microscopy micrographs. This points to applications in the controlled release of targeted substances. The VSM analysis showed that the cellulosic matrices preserved the superparamagnetic characteristics of the NPs. This study suggested a reduced coupling effect between nanoparticles inside polymeric films due to magnetic saturation at low fields. CA0.7FFe and CA1.3FFe composite films reached a saturation magnetization (MSAT) of 46 emu/g around 7 kOe field. Hosting magnetite nanoparticles in cellulose ester matrices may be an interesting way to develop new functional cellulose-based materials, which have the potential for diverse applications, including microelectromechanical systems and microsensors.

IMMOBILIZATION AND STUDY OF TRYPSIN ON MAGNETITE-Fe3O4 NANOPARTICLE-BASED NATURAL AND SYNTHETIC POLYMER HYDROGELS

The presented article designs hydrogel structures with magnetite nanoparticles in the composition, involving various synthetic and natural polymers. The synthesis of magnetite nanoparticles in the hydrogel composition was accomplished through the co-precipitation method, and the immobilization of protein using trypsin as a model drug was investigated. The incorporated of micro-quantities of magnetite Fe3O4 nanoparticles into the gel matrix enhances the affinity for the enzyme, resulting in a significant improvement in specific activity and stability compared to gels without magnetite Fe3O4 nanoparticles. In other words, increasing the degree of immobilization of magnetite Fe3O4 nanoparticles enhances both the immobilization degree and the biological activity of the enzyme. This phenomenon manifests as a continuous interaction between the gel composition and the magnetite nanoparticles of the enzyme

The effect of temperature on the synthesis of magnetite nanoparticles by the coprecipitation method

Magnetic nanoparticles, such as magnetite (Fe3O4), exhibit superparamagnetic properties below 15 nm at room temperature. They are being explored for medical applications, and the coprecipitation technique is preferred for cost-effective production. This study investigates the impact of synthesis temperature on the nanoparticles' physicochemical characteristics. Two types of magnetic analysis were conducted. Samples T 40, T 50, and T 60 displayed superparamagnetic behavior, as evidenced by the magnetization curves. The experiments verified the development of magnetic nanoparticles with an average diameter of approximately dozens of nanometers, as determined by various measurement methods such as XDR, Raman, and TEM. Raman spectroscopy showed the characteristic bands of the magnetite phase at 319, 364, 499, and 680 cm−1. This was confirmed in the second analysis with the ZFC-FC curves, which showed that the samples' blocking temperatures were below ambient temperature. ZFC-FC curves revealed a similar magnetization of about 30 emu/g when applying a magnetic field of 5 kOe.

Plant protein-mediated size-controlled synthesis of magnetite nanoparticles – Studies on optical properties

In today’s scenario nanotechnology has great importance in all scientific and non-scientific sectors. In this study, we have synthesized magnetite nanoparticles coated by the proteins available in the Datura leaf extract through a green and eco-friendly method. From the resulting spectrum obtained on Fe3O4 for different volumes of leaf extract of Datura leaf, the surface plasmon resonance seems to be varying with the volume of capping agent. The data shows that as the volume of capping agent increases the SPR value is shifted to red-end. The Eg values increase with the increasing volume of capping agents. The evaluated band gap (Eg) values are close to semiconductors (0-3 eV). The values indicate that the formed Fe3O4 nanoparticles are marginally semiconducting. The Eg values are found to be dependent upon the volume of the capping agent. The properties of nano-sized semiconductor particles depend on particle size. Here, the absorption peaks (λmax) are consistently increased giving rise to red-shift. The value of surface plasmon resonance shift confirmed that particle size is decreased.
 KEY WORDS: Green synthesis, Magnetite nanoparticles (MNPs), Leaf extract, Band gap, Optical properties, Surface plasmon resonance
 Bull. Chem. Soc. Ethiop. 2024, 38(2), 493-499. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i2.16

Photothermal properties of Fe3O4 nanoparticles coated with turmeric extract

In this study, we synthesized magnetite nanoparticles through a modified coprecipitation route and subsequently coated them directly with Curcuma longa extract. The resulting nanoparticles were then dispersed in distilled water to create a nanofluid. The particle size distribution ranged between 9 to 18 nm according to Transmission Electron Microscopy and Dynamic Light Scattering. The nanofluid’s thermal parameters were obtained by photothermal techniques, obtaining their thermal diffusivity, effusivity, conductivity, and heat capacity per unit volume. The Thermal Wave Resonator Cavity was employed to measure the thermal diffusivity, while the Inverse Photopyroelectric photothermal technique was used to determine the effusivity value. The obtained thermal parameters were close to the carrier liquid (distilled water), being a preliminary study that can be analyzed to improve the heat transfer application in other suspension fluids.

Catalysts Based on Iron Oxides for Wastewater Purification from Phenolic Compounds: Synthesis, Physicochemical Analysis, Determination of Catalytic Activity

In this work, the synthesis of magnetite nanoparticles and catalysts based on it stabilized with silicon and aluminum oxides was carried out. It is revealed that the stabilization of the magnetite surface by using aluminum and silicon oxides leads to a decrease in the size of magnetite nanocrystals in nanocomposites (particle diameter less than ~10 nm). The catalytic activity of the obtained catalysts was evaluated during the oxidation reaction of phenol, pyrocatechin and cresol with oxygen. It is well known that phenolic compounds are among the most dangerous water pollutants. The effect of phenol concentration and the effect of temperature (303–333 K) on the rate of oxidation of phenol to Fe3O4/SiO2 has been studied. It has been determined that the dependence of the oxidation rate of phenol on the initial concentration of phenol in solution is described by a first-order equation. At temperatures of 303–313 K, incomplete absorption of the calculated amount of oxygen is observed, and the analysis data indicate the non-selective oxidation of phenol. Intermediate products, such as catechin, hydroquinone, formic acid, oxidation products, were found. The results of UV and IR spectroscopy showed that catalysts based on magnetite Fe3O4 are effective in the oxidation of phenol with oxygen. In the UV spectrum of the product in the wavelength range 190–1100 nm, there is an absorption band at a wavelength of 240–245 nm and a weak band at 430 nm, which is characteristic of benzoquinone. In the IR spectrum of the product, absorption bands were detected in the region of 1644 cm−1, which is characteristic of the oscillations of the C=O bonds of the carbonyl group of benzoquinone. The peaks also found at 1353 cm−1 and 1229 cm−1 may be due to vibrations of the C-H and C-C bonds of the quinone ring. It was found that among the synthesized catalysts, the Fe3O4/SiO2 catalyst demonstrated the greatest activity in the reaction of liquid-phase oxidation of phenol.

Synthesis and characterization of magnetite coated by maltodextrin for application in magnetic hyperthermia

This study aimed to synthesize magnetite nanoparticles proposing a new core with maltodextrin using the coprecipitation method in an alkaline medium, with the potential application in magnetic hyperthermia for cancer treatment.

Synthesis of magnetite nanoparticles by controlled precipitation under oxidative atmosphere

Fe3O4 nanoparticles have been extensively studied due to their electromagnetic characteristics. Magnetite NPs can be produced by different methods. However, most of the methods use an inert atmosphere for synthesis. Therefore, this work aimed to produce magnetite NPs using the controlled precipitation method under an oxidant atmosphere. The synthesis was carried out using iron chloride, iron sulfate and ammonium hydroxide as reagents. Temperature, dripping time and stirring speed were the controllable variables. The NP powders were characterized by structural (XRD, FTIR), magnetic (vibrating sample magnetometry, VSM), and morphological (TEM) analyses. The results show particles ranging from 4 to 10 nm, with specific surface area of 52 m2/g and irregular morphology. The saturation magnetization (Ms) was 51.5 emu/g. The photocatalytic activity tests showed over 80 % discoloration of the methylene blue dye within 120 min. Therefore, the synthesis of magnetite NPs by the precipitation method under oxidative atmosphere was efficient.

Chitosan-coated magnetic nanorods and nanospheres: physicochemical characterizations and potential as methotrexate carriers for targeted drug delivery

Abstract Spherical magnetite nanoparticles were employed in the almost all magnetic based drug delivery studies. But as we all know the shape of employed particles is one of the major deterministic properties that can significantly affect the physicochemical and biological features of nanostructures and so can fluctuate efficiency of drug delivery. However, it is worthy of consideration that so far no study has investigated the effect of the shape of nanoparticles in drug delivery. To some extent this deficiency in publications may be due to the fact that the synthesis of other forms of magnetite nanoparticles is not as developed as spherical nanoparticles. But recent experiments paved the way for the synthesis of magnetite nanoparticles specially magnetite nanorods (MNRs). So, for the first time, in the current experiment magnetite nanospheres (MNSs) and MNRs were compared in the potential for drug delivery. Chitosan is a natural and biocompatible compound that widely employed as coating material for the fabrication of anticancer drug nano-carriers. So in the present study this carbohydrate was chosen as coating material for the magnetic nanostructures. MNSs were synthesized via a co-precipitation reaction, and MNRs were obtained from the chemical reduction of iron oxide hydroxide (FeOOH) nanorods. Both nanostructures were loaded with methotrexate (MTX), and the release of the drug was measured. The chitosan-coated MNSs (C@MNSs) were 7–18 nm in diameter, and the chitosan-coated MNRs (C@MNRs) were 5–21 nm in width and 29–108 nm in length and had a porous structure. The C@MNSs had a magnetic saturation of ∼80 emu/g, whereas that for the C@MNRs was ∼45 emu/g. The synthesized nanostructures exhibited low toxicity and were able to release the drug inside the cells. The findings of this study demonstrate the suitability of C@MNRs as an alternative to spherical nano-carriers for the efficient and contained delivery of anticancer drugs to designated target cells.

Anionic polymer-coated magnetic nanocomposites for immobilization with palladium nanoparticles as catalysts for the reduction of 4-nitrophenol

This study focuses on the synthesis of magnetite nanoparticles (MNP) coated with poly(poly(ethylene glycol) methacrylate) (PPEGMA) and/or poly(acrylic acid) (PAA) to anchor palladium nanoparticles (Pd) for their application as recyclable catalysts in the reduction of 4-nitrophenol (4NP). It was hypothesized that the abundance of oxygen atoms in PPEGMA enabled coordination with the Pd and provided good water dispersibility of the nanocomposites, while anionic PAA stabilized Pd and reduced the catalyst aggregation through electrostatic repulsion. Three different polymer coatings on MNP (PAA, PPEGMA, and PAA-co-PPEGMA polymers) were investigated to assess their influence on both the catalytic activity and reusability of the catalysts. Transmission electron microscopy (TEM) analysis indicated the distribution of spherical Pd nanoparticles (3–5 nm in diameter) and MNP (9–12 nm in diameter). Photocorrelation spectroscopy (PCS) revealed an average hydrodynamic size of the catalysts ranging from 540 to 875 nm in diameter, with a negative charge on their surface. The Pd content of the catalysts ranged from 4.30 to 6.33% w/w. The nanocomposites coated with PAA-co-PPEGMA polymers exhibited more favorable catalytic activity in the 4NP reduction than those coated with PAA or PPEGMA homopolymers. Interestingly, those containing PAA (e.g., PAA and PAA-co-PPEGMA polymers) exhibited good reusability for the 4NP reduction with a slight decrease in their catalytic performance after 26 cycles. This indicates the important role of carboxyl groups in PAA in maintaining high tolerance after multiple uses.Graphical abstract

Mill Scale-Derived Magnetite Nanoparticles: A Novel Substrate for Lactate Oxidase-Based Biosensors.

Recycling and revalorization of waste are currently essential for sustainable growth. Mill scale, a waste product from steel production industries, which contains high levels of iron and minimal impurities, is proposed in this study as the source to synthesize magnetite nanoparticles (Fe3O4) for an enhancement of a lactate biosensor range. The synthesized Fe3O4 nanoparticles were coated with polydopamine (PDA) to prevent aggregation and degradation, creating a stable platform for immobilizing lactate oxidase enzyme (LOx) on their surfaces. The characterization of the Fe3O4@PDA material was carried out using transmission electron microscopy (TEM), dynamic light scattering (DLS), and measurement of the polydispersity index (PdI). The Fe3O4@PDA-LOx material was then deposited on a screen-printed carbon electrode modified with Prussian blue (SPCE-PB) for lactate detection. The biosensor exhibited a broad, dual linear concentration-response range, one from 0.1 to 4.62 mM with a limit of detection of 0.32 mM and sensitivity of 1.54 μAmM-1cm-2, and another one from 4.62 to 149.21 mM with a limit of detection of 6.31 mM and sensitivity of 0.08 μAmM-1cm-2. The dual-range concentration response of the biosensor makes it an ideal tool for lactate determination in various applications, including sports medicine, clinical diagnosis, and industrial bioprocessing.