Ferrite Magnetic Nanoparticles Research Articles

Removal of 4-nitrophenol and indigo carmine dye from wastewaters by magnetic copper ferrite nanoparticles: Kinetic, thermodynamic and mechanistic insights

Magnetic copper ferrite nanoparticles, CuFe2O4-NPs (CFN) were synthesized via a facile sol–gel method for the effective removal of 4-nitrophenol (4-NP) and indigo carmine dye (IC) as typical hazardous organic pollutants from wastewater. The texture, morphology, and composition of the synthesized CuFe2O4 NPs were thoroughly explored by various physicochemical techniques. Various factors affecting the dye adsorption including the effect of adsorbent mass, contact time, pH, initial IC concentration, and temperatures were investigated to determine the optimum conditions for IC dye removal. The impact of diverse species and other coexisting dyes on the adsorption capacity of CFN was investigated. Five adsorption isotherms were investigated using two-parameters (Tekman, Langmuir, and Freundlich) and three-parameters (Sips, and Redlich-Peterson) models. CFN exhibited a maximum adsorption capacity of 57.4 mg/g according to the Sips model, with optimal conditions observed at pH 3, a contact time of 90 min, and an adsorbent mass of 0.1 g. Thermodynamic data revealed both the endothermic nature of dye removal and the random arrangement of dye molecules onto CFN adsorbent. The IC dye elimination mechanism was elucidated. Furthermore, the CFN-catalyzed reduction of 4-nitrophenol by NaBH4 followed first-order kinetics at a high rate of 0.4365 min−1, reflecting the high catalytic capacity of the synthesized CFN. The magnetic features, cost-effectiveness, recyclability, and high adsorption and catalytic activities towards IC dye and 4-NP removals made the synthesized CFN a promising catalyst for wastewater remediation.

Enhanced Laccase Activity and Stability as Crosslinked Enzyme Aggregates on Magnetic Copper Ferrite Nanoparticles for Biotechnological Processes

AbstractHighly stable and reusable magnetic crosslinked enzyme aggregates (m‐CLEAS) of laccase are synthesized with simultaneous improved enzymatic activity. Magnetic copper ferrite nanoparticles (CFNPs) were synthesized by solvothermal procedure with an average size of ~8 nm. The nanometric m‐CLEAS were formed by co‐aggregation of enzyme with CFNPs and crosslinked using glutaraldehyde. Different mass ratios of CFNPs:Laccase were assayed (1 : 2, 1 : 3, and 1 : 6), where 1 : 6 resulted in the highest activity recovery (97 %). The m‐CLEAS showed an average size of ~239 nm, ~24 % enzyme immobilization efficiency, and loading as high as 1.75 g of protein per g of support. As expected, m‐CLEAS oxidized the substrate with a higher transformation rate (kcat) and catalytic efficiency (kcat/Km) than the free enzyme. m‐CLEAS showed superior storage and thermostability compared to free enzyme and non‐magnetic CLEAS. In particular, the m‐CLEAS showed ~150 % and ~100 % residual activity after 30 days of storage at 4 °C and room temperature, respectively. Furthermore, m‐CLEAS showed good recyclability, retaining ~78 % and ~54 % laccase activity after 5 and 10 cycles of reuse, respectively. This work highlights the facile and cost‐effective synthesis of nanometric m‐CLEAS with exceptional storage stability and simultaneously improved laccase activity, making them suitable for a range of green industrial processes.

Magnetic ferrite nanoparticles coated with bovine serum albumin and glycine polymers for controlled release of curcumin as a model

To conquer the low water solubility and bioavailability of curcumin (CUR), to corroborate its functional qualities and to broaden its applicability in the pharmaceutical sector, numerous nanoscale methods have been widely exploited for its administration. Because of its polycystic, biodegradable, biocompatibility, non-toxicity, and non-allergenic properties, bovine serum albumin (BSA) and glycine (Gly) have been actively investigated as natural biopolymers for decades. Various BSA and Gly-based nanocarriers with unique features for CUR delivery, such as magnetic ferrite nanoparticles, are being developed (MNPs). In this work, magnesium ferrite (MgFe2O4)/BSA and nickel ferrite (NiFe2O4)/Gly nanocomposites loaded with CUR (drug model) were manufactured for the first time using a chemical co-precipitation approach to create biocompatible drug nanocarriers. It was found that the synthesized MgFe2O4/BSA and NiFe2O4/Gly nanoparticles have a uniform particle distribution and their size is much less than 100 nm. Saturation magnetization in MgFe2O4 and NiFe2O4 reaches 13.07 and 33.4 emu/g the remarkable peak of magnetization decreases to 10.99 and 32.36 emu/g after the addition of polymers. These analyses also showed the presence of chemical bonds in the structure of the nanocomposite. The curcumin diffusion process in NPs were determined using a mathematical modeling. The yielding of the product for MgFe2O4/BSA and NiFe2O4/Gly in 200 h is about 72 and 63%, respectively. Also, regressed relative diffusivities (D/R2), including effective steric hindrance, were determined as 5.75 × 10−4 and 2.72 × 10−4 h−1 for MgFe2O4/BSA and NiFe2O4/Gly, respectively. It shows that there is a significant steric barrier that significantly deviates from the molecular diffusion of the liquid. As a result, the low effective release of curcumin in the particles is more noticeable. Our study demonstrated the effective relationship between the polymer architecture and the biophysical properties of the resulting nanoparticles and shed light on new approaches for the design of efficient NP-based drug carriers.

Optimization of Visible-Light-Driven Ciprofloxacin Degradation Using a Z-Scheme Semiconductor MgFe2O4/UiO-67.

A heterogeneous photocatalyst, MgFe2O4/UiO-67 (MU-x), was successfully synthesized by doping magnetic magnesium ferrite nanoparticles (MgFe2O4) with the UiO-67 metal-organic framework at various weight ratios (MgFe2O4: UiO-67 at 30, 50, 70, and 90 wt %). Various techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR) , Brunauer-Emmett-Teller (BET), photoluminescence (PL), vibrating sample magnetometry (VSM), electrochemical impedance spectroscopy (EIS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), were used to characterize the prepared photocatalysts. The photocatalytic performance of MU-x in the degradation of ciprofloxacin (CIP) under visible light was assessed. The CIP degradation efficiency was found to increase as the amount of MgFe2O4 in the composite was increased up to 70 wt %. Experimental conditions were optimized using response surface methodology (RSM) based on central composite design (CCD) with three factors: initial pH, catalyst loading, and CIP concentration. Using the obtained model, the optimal conditions were determined as follows: initial pH of 8.025, catalyst loading of 33.8 wt %, and CIP concentration of 10.8 mg/L. Under these optimal conditions, a notable improvement was achieved, with 99.62% of CIP removal achieved within 90 min, surpassing the performance of previously reported photocatalysts. Total organic carbon (TOC) analysis revealed a high degree of mineralization, at 81.25%. The degradation pathway of CIP was investigated based on liquid chromatography-mass spectrometry (LC-MS) analysis. Finally, the values of ECB and EVB of the photocatalyst were determined and the possible degradation mechanism of CIP was investigated based on Mott-Schottky and the applied scavengers. The hydroxyl radical (•OH) was identified as the dominant species in the removal of CIP through a trapping experiment. The photocatalyst with 70 wt % of MgFe2O4 (MU-70) exhibited excellent stability and recoverability with an external magnet, demonstrating 86.33% CIP removal after four cycles. According to the obtained results, MU-70 is a promising visible-light-active photocatalyst with great potential for water treatment applications and convenient recovery.

The thermo-therapeutic applications of Chitosan- CTAB coated Nickel Ferrite (NiFe2O4) magnetic nanoparticles

In this study, we used a hydrothermal-assisted co-precipitation method to synthesize the nickel ferrite (FN), Chitosan coated nickel ferrite (FN-Ch) and cetyltrimethylammonium bromide coated nickel ferrite (FN-CT) nanoparticles with small sizes and good biocompatibility. These nanoparticles were then evaluated for their potential use in magnetic hyperthermia. The particles were characterized using a variety of techniques, including x-ray diffraction, transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, Thermogravimetric Analysis (TGA), Inductively coupled plasma (ICP), magnetic characterization (VSM), zeta potential analysis, and in vivo studies (blood hemolysis and MTT test). The results of the x-ray diffraction analysis showed that the nanoparticles had a spinel phase of NiFe2O4. TEM analysis revealed that all three samples contained particles with nearly quadrilateral and hexagonal shapes. FT-IR spectroscopy confirmed the presence of Chitosan and CTAB coatings on the particle surface. Magnetic hysteresis curves showed that all of the synthesized samples exhibited superparamagnetic behavior at room temperature. The findings from the ICP analysis indicated that the FN-Ch and FN-CT nanoparticles contained iron and nickel, while no substantial quantities of other trace elements were identified in either of the samples. Blood hemolysis and MTT tests were used to assess the toxicity of the nanoparticles when in contact with red blood cells, fibroblast cells, and MCF7 cancer cells. Overall, our findings suggest that FN-Ch and FN-CT nanoparticles have potential for use in cancer diagnosis and treatment as part of a new nano-carrier system. Furthermore, combining hyperthermia with other treatment methods could enhance the effectiveness of cancer therapy.

Simplified Synthesis of the Amine-Functionalized Magnesium Ferrite Magnetic Nanoparticles and Their Application in DNA Purification Method.

For pathogens identification, the PCR test is a widely used method, which requires the isolation of nucleic acids from different samples. This extraction can be based on the principle of magnetic separation. In our work, amine-functionalized magnesium ferrite nanoparticles were synthesized for this application by the coprecipitation of ethanolamine in ethylene glycol from Mg(II) and Fe(II) precursors. The conventional synthesis method involves a reaction time of 12 h (MgFe2O4-H&R MNP); however, in our modified method, the reaction time could be significantly reduced to only 4 min by microwave-assisted synthesis (MgFe2O4-MW MNP). A comparison was made between the amine-functionalized MgFe2O4 samples prepared by two methods in terms of the DNA-binding capacity. The experimental results showed that the two types of amine-functionalized magnesium ferrite magnetic nanoparticles (MNPs) were equally effective in terms of their DNA extraction yield. Moreover, by using a few minutes-long microwave synthesis, we obtained the same quality magnesium ferrite particles as those made through the long and energy-intensive 12-h production method. This advancement has the potential to improve and expedite pathogen identification processes, helping to better prevent the spread of epidemics.

Structural and magnetic properties of cobalt ferrite nano-particles

This paper delves into the comprehensive study of the structural and magnetic properties of cobalt ferrite nanoparticles, magnetic Cobalt Ferrite nanoparticles were successfully synthesised by the sol–gel method using the needed precursors in the desired amount. The resultant CFO nanoparticle prepared is black, and XRD results say that the prepared cobalt ferrite has an average particle size of 37 nm which has been confirmed the same by HR-TEM. XPS confirmed the occupancy of cation at octahedral and tetrahedral site. RAMAN displays all its five modes, confirming the presence of cobalt ferrite. A vibrating sample magnetometer (VSM) was applied to determine magnetic characteristics at room temperature.

An Efficient One-Pot Synthesis of Octahydroquinazolinone Derivatives Using Magnetic Cobalt Ferrite Catalyst

In this work, octahydroquinazolinone derivatives were synthesized using magnetic cobalt ferrite nanoparticles using oxalate precursor method. The XRD pattern and IR spectrum confirmed the formation of single segment cubic spinel cobalt ferrite. The average size of the crystallites was determined to be 26.599 nm, while the lattice constant was found to be 8.365 Å. A fine spherical CoFe2O4 particles with some quantity of aggregation may be observed within the SEM and TEM images. Nano spinel cobalt ferrite nanoparticles is a easily synthesized, non-toxic, less expensive, effortlessly magnetically recoverable and green catalyst for the synthesis of octahydroquinazolinone derivatives through the condensation of aromatic aldehydes with urea or thiourea and dimedone. The advantages of this technique are quick reaction time, ease of product isolation and high yields.

(Invited) Demonstration of ATPS Phase Separation, B-Field Concentration and Manipulation of Sars-Cov-2 Viral Particles

A technology, based on fluorescence sensing in a liquid sample and capable for an early detection of a pathogen at extremely low concentration, is very desirable though equally challenging to develop. In optical sensors, a typical fluorescent signal would be too weak to measure without special tools, unless the detected analyte, tagged with a fluorescent label, can be separated and concentrated.In this work a new combined technology[1] will be presented. An assembly of a monoclonal antibody (mAb) functionalized with a fluorescent tag with the S-proteins at the surface of inactivated coronavirus is achieved. In order to separate a bound fluorescent tag (signal) and free tag molecules (background), we simultaneously attach to the virus surface ferrite magnetic nanoparticles (mNP) functionalized with the mAb (without fluorescent tag). Since the surface of the SARS-CoV2 virus has a large number of binding sites, a "sandwich" assembly of mNP-mAb:virus:mAb-FL happens. At the same time, non-specific binding of the fluorescent tag to mNPs is excluded. As a result, the fluorescent tag bound to the analyte can be manipulated by magnetic force and moved with respect to (unused) free tag molecules.Fig.1 shows the fluorescence signal of the mNP-mAb:virus:mAb-FL sandwich assemblies, that were first concentrated by an aqueous two-phase system separation (ATPS)[2] – carefully designed mix of PEG/dextran solutions. Upon dividing the ATPS into PEG bulk phase and dextran bubbles, the viral assemblies (and free non-bound tag) were separated into the PEG phase. Applying vertical magnetic field as shown in the figure resulted in additional significant concentration of the assemblies against the wall of a dextran bubble. Thus, we achieved a clear separation of the virus (as detected by direct fluorescence signal) with respect to the free tag molecules (background) residing in the bulk solution.[1] Vyacheslav V. Rotkin, Ming Zheng, Tetyana Ignatova, Daniel Hayes, Suresh Kuchipudi; Methods and systems for early detection of viral diseases. https://patents.google.com/patent/US20210364517A1[2] Albertsson, P. A., Partition of Cell Particles and Macromolecules. first ed.; Wiley: New York, 1986. Acknowledgement: This work has been supported by NSF (CHE-2032582 and CHE-2032601). Figure 1

Removing heavy metal ions from wastewater by Chlorella sorokiniana coupled to manganese-doped magnetic ferrite nanoparticles

In this study, we investigated the benefit of combining Chlorella sorokiniana with manganese-containing ferrite nanoparticles (NPs) for heavy metal removal and cell harvesting. Our results demonstrate that the combination of non-toxic nanoparticles significantly enhances the heavy metal removal capacity of C. sorokiniana without affecting its growth. The microalgae combined with NPs was able to sequester Cr6+, Co2+, and Ni2+ from aqueous solutions and could remove these metals at a higher adsorption capacity and within a relatively short time than their individual counterparts, indicating a synergistic effect between the algal cells and the nanomaterials, where bioadsorption and chemisorption were the main players. Both biosorption and chemisorption capacities were found to be the highest for single-metal systems and decreased when coexisting ions were present in the solution. The adsorption of the heavy metals evaluated was better described by the pseudo-second order model than the pseudo-first order model, indicating that chemisorption dominated over physisorption. These characteristics suggest that the combination of biosorbents with nanosorbents is a promising approach for the treatment of water contaminated with heavy metals making this process more efficient, economical, sustainable, and clean.

Fabrication of an ultra-sensitive electrochemical DNA biosensor based on CT-DNA/NiFe2O4NPs/Au/CPE for detecting rizatriptan benzoate

A novel and first electrochemical biosensor based on Deoxyribonucleic acid (DNA) as a biological component to measure an antimigraine drug, rizatriptan benzoate (RZB) for patients under treatment in biological samples was developed. A carbon paste electrode (CPE) was modified by calf thymus (CT) double-stranded (ds)-DNA, nickel ferrite magnetic nanoparticles (NiFe2O4NPs), and gold nanoparticles (AuNPs). The morphology of the CT-DNA/NiFe2O4NPs/AuNPs/CPE was characterized by Field emission scanning electron microscope (FESEM). The presence of NiFe2O4NPs and AuNPs was confirmed by energy-dispersive X-ray spectroscopy (EDS) image of the NiFe2O4NPs/AuNPs/CPE surface. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to determine the structure and electrochemical characteristics of the CT-DNA/NiFe2O4NPs/AuNPs/CPE. Differential pulse voltammetry (DPV) was used to investigate the electrochemical behavior of RZB. Chronoamperometry (CA) was applied to study the effect of CT-DNA immobilization time on the peak oxidation current of RZB accumulated on the surface of the CT-DNA/NiFe2O4NPs/AuNPs/CPE. The results showed that, under optimum conditions, the prepared electrode responded linearly to RZB concentrations between 0.01 and 2.0 μM, with a 0.0033 μM detection limit (LOD) and 0.01 μM limit of quantification (LOQ). The parameters influencing the biosensor performance (temperature, CT-DNA immobilization time, and RZB/CT-DNA accumulation time) were optimized. DPV showed the displacement of the peak potential towards positive values and the reduction of its current, indicating that the drug could intercalate between the guanine base pairs of CT-DNA. Our biosensor was successfully applied for RZB measurement in human urine, blood serum, plasma samples, and tablets. The presented biosensor was fast response, sensitive, selective, cost-effective, and easy-to-use for RZB determination in pharmaceutical formulations and biological samples.

Effect of manganese ion doping on magnetic properties and magnetic induction heating of Zn-Al ferrite nanoparticles

Magnetic induction hyperthermia (MIH) is a new kind of cancer treatment that preferentially targets tumor cells due to their poor heat resistance. In recent years, ferrite magnetic nanoparticles with spinel structures that can self-regulate the temperature of hyperthermia have been widely used in MIH. Importantly, substituting ions with different magnetic moments in magnetic nanoparticles can effectively regulate their Curie temperature and heating efficiency. Here we investigate the influence of Mn2+ doping on the magnetic properties, Curie temperature, and the heating efficiency of hydrothermally synthesized MnxZn1-xAl0.4Fe1.6O4 (0.4 ≤ x ≤ 0.8) nanoparticles. With increasing substitution of Zn2+ content by Mn2+, the mass magnetization increases from 30.2 to 54.2 emu g−1, the Curie temperature increases from 47.5 to 257.8 ℃, and the heating efficiency (specific loss power, SLP) increases from 6.3 to 54.5 W g−1, respectively. Of note, aqueous suspensions of Mn0.5Zn0.5Al0.4Fe1.6O4 nanoparticles demonstrate self-regulated temperature hyperthermia at 45.4 ℃ in vitro with the SLP of 11.1 W g−1 under clinically safe alternating magnetic field, manifesting a combination of high heating efficiency and clinically desirable therapeutic temperature. This study provides a new class of magnetic nanoparticles potentially useful for fast and safe MIH for cancer treatment.

CuFe2O4 Magnetic Nanoparticles as Heterogeneous Catalysts for Synthesis of Dihydropyrimidinones as Inhibitors of SARS-CoV-2 Surface Proteins—Insights from Molecular Docking Studies

In this study, we present the highly efficient and rapid synthesis of substituted dihydropyrimidinone derivatives through an ultrasound-accelerated approach. We utilize copper ferrite (CuFe2O4) magnetic nanoparticles as heterogeneous catalysts, employing the well-known Biginelli reaction, under solvent-free conditions. The impact of the solvent, catalyst amount, and catalyst type on the reaction performance is thoroughly investigated. Our method offers several notable advantages, including facile catalyst separation, catalyst reusability for up to three cycles with the minimal loss of activity, a straightforward procedure, mild reaction conditions, and impressive yields, ranging from 79% to 95%, within short reaction times of 20 to 40 min. Furthermore, in the context of fighting COVID-19, we explore the potential of substituted dihydropyrimidinone derivatives as inhibitors of three crucial SARS-CoV-2 proteins. These proteins, glycoproteins, and proteases play pivotal roles in the entry, replication, and spread of the virus. Peptides and antiviral drugs targeting these proteins hold great promise in the development of effective treatments. Through theoretical molecular docking studies, we compare the binding properties of the synthesized dihydropyrimidinone derivatives with the widely used hydroxychloroquine molecule as a reference. Our findings reveal that some of the tested molecules exhibit superior binding characteristics compared to hydroxychloroquine, while others demonstrate comparable results. These results highlight the potential of our synthesized derivatives as effective inhibitors in the fight against SARS-CoV-2.

Designed ultrafine polymer-coated manganese-cobalt ferrite nanoparticles loaded with anticancer drug: efficacy enhancement through host:guest complexation on the polymer surface

Magnetic nanomaterials of different compositions have been examined, focusing on the magnetic field-directed transport of drugs. The size, shape, surface modification and composition variations make every magnetic nanostructure a unique nanocarrier. In this work, we carry out a hydrothermal synthesis of novel manganese-cobalt co-incorporated magnetic ferrite nanoparticles. The particles are characterized using x-ray diffraction, transmission electron microscopy, thermogravimetry and x-ray photoelectron spectroscopy. The size of the nanoparticles is below 10 nm, and they are found to fall under the face-centered cubic system. The nanoparticles are coated with the β-cyclodextrin and folate co-tethered polyethylene glycol. Vibrating sample magnetometry reveals the soft ferromagnetic nature of the nanoparticles with a saturation magnetization value of 28.11 emu g−1 for the coated nanoparticles. The polymer on the nanoparticles allows the loading of the drug feasible, and the encapsulation efficiency is ∼93%. The in vitro release of the drug is monitored and it is observed that the release occurs over 130 h. The cytotoxicity of the free- and camptothecin-loaded manganese-ferrite nanocarrier on breast cancer cell lines is investigated. The IC50 value of the drug-loaded nanocarrier is 2.22 µg mL−1 which is significantly lower than that of the free drug. The drug-encapsulated nanocarrier releases the cargo slowly and continuously and shows increased efficacy, which represents the significance of the nanocarrier. The results present the designed nanomaterial as a suitable anticancer drug vehicle.

Investigation on the catalytic performance of magnetic copper ferrite nanoparticles in the catalytic hydroconversion of Hanglaiwan long flame coal

Magnetic copper ferrite (CuFe2O4) was prepared by hydrothermal synthesis method and used for the catalytic hydroconversion (CHC) of Hanglaiwan long flame coal (HLFC) in cyclohexane under 1 MPa of initial hydrogen pressure (IHP) at 300 °C for 4 h. The total yield of soluble portion (SP) from the CHC is 33.7 wt%, significantly being higher than that (10.5 wt%) from the non-CHC (NCHC) under the same conditions. The main compounds detected in SPCHC (for CHC) are arenes and oxygen-containing organic compounds (OCOCs). Benzyloxybenzene (BOB), 2-(benzyloxy)naphthalene (BON), oxybis(methylene)dibenzene (OBMDB), oxydibenzene (ODB), and 2,2′-oxydinaphthalene (ODN) were used as HLFC-related model compounds to investigate the catalytic activity of CuFe2O4 and understand the CHC mechanism of HLFC. According to the model reactions, CuFe2O4 activates H2 to biatomic active hydrogen (H…H) and splits H…H to mobile H+ and immobile H-. H+ addition to oxygen atoms (OAs) in >C-O- bridged bonds (BBs) cleaves the BBs and releases SP during the CHC of HLFC.

One pot, scalable synthesis of hydroxide derived ferrite magnetic nanoparticles

Herein we describe a new, quite simple, highly scalable, one-pot protocol for the synthesis of ferrite nanoparticles, NPs. We immerse water insoluble iron boride, FeB, powders – in plastic bottles at temperatures between 50 °C and 80 °C and ambient pressures – for tens of hours in high pH aqueous solutions of potassium-, sodium-, tetramethylammonium-, or tetrabutylammonium-hydroxides. The resulting powder is comprised of iron oxide, Fe3O4, NPs with, in one case, a saturation magnetization of 75 Am2kg−1, that exhibit ferrimagnetic behavior, with a critical temperature of 820 K. The same protocol was used to convert water soluble iron sulphate, FeSO4, to the same NPs. The average size of the NPs depends on reaction time; after 24 h, they are in the 15 nm range; after 48 h, they are closer to 25 nm. While our approach may appear to be similar to the co-precipitation method for making such NPs, we make a strong case that our approach is significantly simpler, nonetheless reaching high magnetization of NPs.

Removal of nitrobenzene from aqueous solution using manganese ferrite nanoparticles

Magnetic manganese ferrite (MnFe2O4) nanoparticles were successfully synthesized via a chemical co-precipitation route. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopies (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and N2 adsorption-desorption isotherms. MnFe2O4 nanoparticles showed effective adsorption of nitrobenzene from an aqueous solution. The Langmuir and D-R models were well-described adsorption isotherms. The maximum adsorption capacity (qmax) of nitrobenzene onto MnFe2O4 was found to be 64.37 mg/g. The pseudo-second model was the most suitable for the fitting of the experimental kinetic data. The equilibrium adsorption capacity (qe) of MnFe2O4 was 50 mg/g. Thermodynamics data showed nitrobenzene adsorption was spontaneous, and exothermic, with decreased randomness. The regeneration cycle showed that the prepared sample has 80% adsorption capacity after five times adsorption–desorption cycles. MnFe2O4 nanoparticles can be used as a low-cost alternative to commercial for the adsorption of nitrobenzene from an aqueous solution.

Adsorption–precipitation–cross-linking immobilization of GDSL-type esterase from Aspergillus niger GZUF36 by polydopamine-modified magnetic clarity tetroxide nanocouplings and its enzymatic characterization

Recombinant INANE1 (rINANE1), a recombinant intracellular GDSL-type esterase from Aspergillus niger GZUF36, has high acetate substrate specificity. Here, rINANE1 was successfully immobilized on polydopamine (PDA)-modified magnetic ferric oxide nanoparticles (Fe3O4NPs) by adsorption–precipitation–cross-linking to obtain cross-linked enzyme aggregate (CLEA)–rINANE1–Fe3O4@PDA. Fe3O4, Fe3O4@PDA, and CLEA–rINANE1–Fe3O4@PDA were characterized by scanning electron microscopy, X-ray diffraction, vibrating-sample magnetometry, Fourier transform infrared (FTIR) spectroscopy, and zeta potential analysis. Upon immobilization, CLEA–rINANE1–Fe3O4@PDA, with a protein loading of 72.72 ± 1.01 mg/g, reached optimal activity recovery of 104.40 % ± 1.14 %. FTIR analysis showed that immobilization increased the relative content of β-folding in rINANE1 by 12.25 % and reduced irregular curl by 4.16 %, rendering the structure more orderly. Specifically, under an alkaline condition (pH 10), CLEA–rINANE1–Fe3O4@PDA performed over 100 % of initial activity. The optimum temperature increased by 5 °C, and over 55 % of the initial activity was observed after 12 h at 55 °C. CLEA–rINANE1–Fe3O4@PDA showed over 40 % of its relative activity, whereas free rINANE1 showed <10 % in acetonitrile. In addition, the relative activity of CLEA–rINANE1–Fe3O4@PDA was retained at about 80 % after eight cycles and maintained at 109 % after 45 days. The PDA-modified magnetic ferrite nanoparticles exhibited excellent stability and recyclability, providing a new avenue for developing industrial biocatalysts.

Immobilization of fatty acid photodecarboxylase in magnetic nickel ferrite nanoparticle

Fatty acid photodecarboxylase in Chlorella variabilis NC64A (CvFAP) performed excellent ability to exclusively decarboxylate renewable fatty acids for C1-shortened hydrocarbons fuel production under visible light. However, the large-scale application by such an approach is limited by the free state of CvFAP catalyst, which is unstable for efficient biofuel production. In this study, CvFAP was immobilized in magnetic nickel ferrite (NiFe2O4) nanoparticles for facile recovery by a simple procedure. The shift of Ni 2p in electron binding energy was detected to clarify the interaction between Ni2+ and histidine of CvFAP. The coordination of NiFe2O4 and CvFAP contributed to an efficient affinity binding with an immobilization capacity of 98 mg/g carrier. Hydrocarbon fuel concentration of 3.7 mM was obtained by NiFe2O4@CvFAP-induced photoenzymatic decarboxylation. The high stability of CvFAP in terms of residual enzyme activity of 79.7% at pH 9.0 and that of 68% at organic solvent ratio of 60%, respectively, were observed.

A novel dual-responsive bio-derived magnetic nanocomposite: An excellent catalyst for efficient photodegradation of contaminants and detection of food additive in wastewater

Industrial development has been a global issue due to massive disposal of pollutants in water bodies. Considering this, many researchers adopt photocatalysis as an efficient technology for coordinated abatement of pollutants from wastewater. However, designing of materials that grant dual applicability in removal as well as detection of pollutant is still a challenge. Thus, demonstrated herein were bio-derived bi-functional hybrid magnetic nanocomposites that presented high photocatalytic degradation and electrochemical detection of noxious contaminants in wastewater. Magnetic nickel ferrite (NF) nanoparticles were organized on bio-derived template constructed from carboxylated cellulose (CCL) and carboxylated graphene oxide (CGO) via facile hydrothermal treatment to fabricate CCL-CGO-NF nanocomposites which were validated through various characterization techniques such as FT-IR, Powder XRD, FE-SEM, HR-TEM, EDX, XPS and VSM studies. The photocatalytic activity was investigated for degradation of three virulent model contaminants: Fast green (FG), Levofloxacin (LV) and p-Nitrophenol (PNP). Results displayed higher degradation efficiency of CCL-CGO-NFx nanocomposites than pure NF with highest degradation of 98%, 75% and 94% for FG, LV and PNP, respectively using CCL-CGO-NF70. Moreover, CCL-CGO-NF70 was employed for electrochemical sensing of FG that exhibited low detection limit of 1 μM in concentration range of 5–1200 μM. The nanocomposite established good stability, repeatability, reproducibility and sensitivity in real samples that certifies its dual practical applicability in environment detoxification as a photocatalyst and an electrochemical sensor. Finally, social implications and future perspectives concerning this proposed method was discussed.