Radiation-Induced Synthesis and Superparamagnetic Properties of Ferrite Fe3O4 Nanoparticles

Ultra-small magnetic Fe3O4 nanoparticles are successfully synthesized in basic solutions by using the radiolytic method of the partial reduction in FeIII in the presence of poly-acrylate (PA), or by using the coprecipitation method of FeIII and FeII salts in the presence of PA. The optical, structural, and magnetic properties of the nanoparticles were examined using UV-Vis absorption spectroscopy, high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and SQUID magnetization measurements. The HRTEM and XRD analysis confirmed the formation of ultra-small magnetite nanoparticles in a spinel structure, with a smaller size for radiation-induced particles coated by PA (5.2 nm) than for coprecipitated PA-coated nanoparticles (11 nm). From magnetization measurements, it is shown that the nanoparticles are superparamagnetic at room temperature. The magnetization saturation value Ms = 50.1 A m2 kg-1 of radiation-induced nanoparticles at 60 kGy is higher than Ms = 18.2 A m2 kg-1 for coprecipitated nanoparticles. Both values are compared with nanoparticles coated with other stabilizers in the literature.

Effect of Organic Coating Variation on the Electric and Magnetic Behavior of Ferrite Nanoparticles

Organic ligand coatings can modify the surface properties of nanoparticles. With the proper choice of the type of nanoparticles and of the ligand, a targeted modification can be achieved that is suitable for specific applications. In the present work, we employ density functional theory calculations with Hubbard corrections (DFT + U) to treat localized states in order to investigate the magnetic and electrostatic properties of ferrite nanoparticles (CoFe2O4 and Fe2O3) covered with COOH-terminated [oleic acid (OA)] and OH-terminated [diethylene glycol (DEG)] ligands by varying the ligands coverage. OA results in a decrease of the mean magnetic moment for both particles as the coating coverage increases. The magnetic anisotropy (MAE) significantly decreases for CoFe2O4, whereas for Fe2O3 a significant increase of MAE is found as the OA coverage percentage increases. For DEG, the variation of both types of nanoparticles in the magnetic moment and the magnetic anisotropy is not significant since DEG shows a weaker attachment on the surface. As COOH shows a larger percentage of covalent bonding than OH, a larger amount of charge is transferred to both particles when OA is attached on their surface. In this case, the particles possess a higher charge, and thus they can produce a larger electrostatic potential in the neighborhood independently of the screening by the coating. Thus, the repulsive Coulombic forces are enhanced mainly in the OA coating case, resulting in an enhancement of their colloidal stability.

Cobalt Iron Oxide (CoFe2O4) Nanoparticles Induced Toxicity in Rabbits

The market for nanoparticles has grown significantly over the past few decades due to a number of unique qualities, including antibacterial capabilities. It is still unclear how nanoparticle toxicity works. In order to ascertain the toxicity of synthetic cobalt iron oxide (CoFe2O4) nanoparticles (CIONPs) in rabbits, this study was carried out. Sixteen rabbits in total were purchased from the neighborhood market and divided into two groups (A and B), each of which contained eight rabbits. The CIONPs were synthesized by the co-precipitation method. Crystallinity and phase identification were confirmed by X-ray diffraction (XRD). The average size of the nanoparticles (13.2 nm) was calculated by Scherrer formula (Dhkl = 0.9 λ/β cos θ) and confirmed by TEM images. The saturation magnetization, 50.1 emug-1, was measured by vibrating sample magnetometer (VSM). CIONPs were investigated as contrast agents (CA) for magnetic resonance images (MRI). The relaxivity (r = 1/T) of the MRI was also investigated at a field strength of 0.35 T (Tesla), and the ratio r2/r1 for the CIONPs contrast agent was 6.63. The CIONPs were administrated intravenously into the rabbits through the ear vein. Blood was collected at days 5 and 10 post-exposure for hematological and serum biochemistry analyses. The intensities of the signal experienced by CA with CIONPs were 1427 for the liver and 1702 for the spleen. The treated group showed significantly lower hematological parameters, but significantly higher total white blood cell counts and neutrophils. The results of the serum biochemistry analyses showed significantly higher and lower quantities of different serum biochemical parameters in the treated rabbits at day 10 of the trial. At the microscopic level, different histological ailments were observed in the visceral organs of treated rabbits, including the liver, kidneys, spleen, heart, and brain. In conclusion, the results revealed that cobalt iron oxide (CoFe2O4) nanoparticles induced toxicity via alterations in multiple tissues of rabbits.

Large-scale sonochemical fabrication of a Co3O4-CoFe2O4@MWCNT bifunctional electrocatalyst for enhanced OER/HER performances

Herein, we have prepared a mixed-phase Co3O4-CoFe2O4@MWCNT nanocomposite through a cheap, large-scale, and facile ultrasonication route followed by annealing. The structural, morphological, and functional group analyses of the synthesized catalysts were performed by employing various characterization approaches such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The resultant samples were tested for bifunctional electrocatalytic activity through various electrochemical techniques: cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). The prepared Co3O4-CoFe2O4@MWCNT nanocomposite achieved a very high current density of 100 mA cm-2 at a lower (290 mV and 342 mV) overpotential (vs. RHE) and a smaller (166 mV dec-1 and 138 mV dec-1) Tafel slope in the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively, compared to Co3O4-CoFe2O4. The excellent electrochemical activity of the as-prepared electrocatalyst was attributed to the uniform incorporation of Co3O4-CoFe2O4 over MWCNTs which provides high redox active sites, a greater surface area, better conductivity, and faster charge mobility. Furthermore, the enhanced electrochemical active surface, low charge-transfer resistance (Rct), and higher exchange current density (J0) of the Co3O4-CoFe2O4@MWCNT ternary composite are attributed to its superior behavior as a bifunctional electrocatalyst. Conclusively, this study demonstrates a novel and large-scale synthesis approach for bifunctional electrocatalysts with a high aspect ratio and abundance of active sites for high-potential energy applications.

Preparation of a 3D printable high-performance GelMA hydrogel loading with magnetic cobalt ferrite nanoparticles

Osteosarcoma remains a worldwide concern due to the poor effectiveness of available therapies in the clinic. Therefore, it is necessary to find a safe and effective therapy to realize the complete resection of osteosarcoma and reconstruction of the bone defect. Magnetic hyperthermia based on magnetic nanoparticles can kill tumor cells by raising the temperature without causing the side effects of conventional cancer treatments. This research aims to design a high-performance magnetic hydrogel composed of gelatin methacrylate and highly magnetic cobalt ferrite (CFO) nanoparticles for osteosarcoma treatment. Specifically, CFO is surface functionalized with methacrylate groups (MeCFO). The surface modified CFO has good biocompatibility and stable solution dispersion ability. Afterward, MeCFO nanoparticles are incorporated into GelMA to fabricate a three-dimensional (3D) printable MeCFO/GelMA magnetic hydrogel and then photocross-linked by UV radiation. MeCFO/GelMA hydrogel has high porosity and swelling ability, indicating that the hydrogel possesses more space and good hydrophily for cell survival. The rheological results showed that the hydrogel has shear thinning property, which is suitable as a bioprinting ink to produce desired structures by a 3D printer. Furthermore, 50 μg/mL MeCFO not only decreases the cell activity of osteosarcoma cells but also promotes the osteogenic differentiation of mBMSCs. The results of the CCK-8 assay and live/dead staining showed that MeCFO/GelMA hydrogel had good cytocompatibility. These results indicated that MeCFO/GelMA hydrogel with potential antitumor and bone reconstruction functions is a promising therapeutic strategy after osteosarcoma resection.

Palladium Decorated, Amine Functionalized Ni-, Cd- and Co-Ferrite Nanospheres as Novel and Effective Catalysts for 2,4-Dinitrotoluene Hydrogenation

2,4-diaminotoluene (TDA) is one of the most important polyurethane precursors produced in large quantities by the hydrogenation of 2,4-dinitrotoluene using catalysts. Any improvement during the catalysis reaction is therefore of significant importance. Separation of the catalysts by filtration is cumbersome and causes catalyst loss. To solve this problem, we have developed magnetizable, amine functionalized ferrite supported palladium catalysts. Cobalt ferrite (CoFe₂O₄-NH₂), nickel ferrite (NiFe₂O₄-NH₂), and cadmium ferrite (CdFe₂O₄-NH₂) magnetic catalyst supports were produced by a simple coprecipitation/sonochemical method. The nanospheres formed contain only magnetic (spinel) phases and show catalytic activity even without noble metals (palladium, platinum, rhodium, etc.) during the hydrogenation of 2,4-dinitrotoluene, 63% (n/n) conversion is also possible. By decorating the supports with palladium, almost 100% TDA selectivity and yield were ensured by using Pd/CoFe₂O₄-NH₂ and Pd/NiFe₂O₄-NH₂ catalysts. These catalysts possess highly favorable properties for industrial applications, such as easy separation from the reaction medium without loss by means of a magnetic field, enhanced reusability, and good dispersibility in aqueous medium. Contrary to non-functionalized supports, no significant leaching of precious metals could be detected even after four cycles.

Photocatalytic and Antibacterial Activity of CoFe2O4 Nanoparticles from Hibiscus rosa-sinensis Plant Extract

Biogenic CoFe₂O₄ nanoparticles were prepared by co-precipitation and Hibiscus rosa sinensis plant leaf was used as a bio-reductant of the nanoparticle productions. The biosynthesized CoFe₂O₄ nanoparticles were characterized by XRD, FTIR, UV, VSM, and SEM via EDX analysis. The cubic phase of biosynthesized CoFe₂O₄ nanoparticles and their crystallite size was determined by XRD. The Co-Fe-O bonding and cation displacement was confirmed by FTIR spectroscopy. The presence of spherically-shaped biosynthesized CoFe₂O₄ nanoparticles and their material were confirmed by SEM and TEM via EDX. The super-paramagnetic behaviour of the biosynthesized CoFe₂O₄ nanoparticles and magnetic pulse was established by VSM analysis. Organic and bacterial pollutants were eradicated using the biosynthesized CoFe₂O₄ nanoparticles. The spinel ferrite biosynthesized CoFe₂O₄ nanoparticles generate radical and superoxide ions, which degrade toxic organic and bacterial pollutants in the environment.

Effect of Oleylamine on the Surface Chemistry, Morphology, Electronic Structure, and Magnetic Properties of Cobalt Ferrite Nanoparticles

The influence of oleylamine (OLA) concentration on the crystallography, morphology, surface chemistry, chemical bonding, and magnetic properties of solvothermal synthesized CoFe₂O₄ (CFO) nanoparticles (NPs) has been thoroughly investigated. Varying OLA concentration (0.01-0.1 M) resulted in the formation of cubic spinel-structured CoFe₂O₄ NPs in the size-range of 20-14 (±1) nm. The Fourier transform spectroscopic analyses performed confirmed the OLA binding to the CFO NPs. The thermogravimetric measurements revealed monolayer and multilayer coating of OLA on CFO NPs, which were further supported by the small-angle X-ray scattering measurements. The magnetic measurements indicated that the maximum saturation (M_S) and remanent (M_r) magnetization decreased with increasing OLA concentration. The ratio of maximum dipolar field (H_dip), coercivity (H_C), and exchanged bias field (H_ex) (at 10 K) to the average crystallite size (D_xrd), i.e., (H_dip/D_xrd), (H_C/D_xrd), and (H_ex/D_xrd), increased linearly with OLA concentration, indicating that OLA concurrently controls the particle size and interparticle interaction among the CFO NPs. The results and analyses demonstrate that the OLA-mediated synthesis allowed for modification of the structural and magnetic properties of CFO NPs, which could readily find potential application in electronics and biomedicine.

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

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

Synthesis, characterization and in vitro cytotoxicity study of Co and Ni ferrite nanoparticles prepared by sol-gel method

In this study, we report the synthesis and characterization of NiFe2O4 and CoFe2O4 nanoparticles (NPs) which are widely used in the biomedical area. There is still limited knowledge how the properties of these materials are influenced by different chemical routes. In this work, we investigated the effect of heat treatment over cytotoxicity of cobalt and niquel ferrites NPs synthesized by sol-gel method. Then the samples were studied using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), Fourier Transform Infrared Spectroscopy Analysis (FTIR), and X-ray fluorescence (XRF). The average crystallite sizes of the particles were found to be in the range of 20–35 nm. The hemocompatibility (erythrocytes and leukocytes) was checked. Cytotoxicity results were similar to those of the control test sample, therefore suggesting hemocompatibility of the tested materials.

A robust electrochemical immunosensor based on core-shell nanostructured silica-coated silver for cancer (carcinoembryonic-antigen-CEA) diagnosis

This work addresses the fabrication of an efficient, novel, and economically viable immunosensing armamentarium that will detect the carcinoembryonic antigen (CEA) typically associated with solid tumors (sarcomas, carcinomas, and lymphomas) and is used as a clinical tumor marker for all these malignancies. We synthesized silver nanoparticles by single-step chemical reduction and coated with silica using a modified Stober method to fabricate silica-coated silver core-shell nanoparticles. The morphologies, structure, and size of the nanoparticles were characterized by Transmission Electron Microscopy (TEM), UV-Visible spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infra-Red Spectroscopy (FTIR), and Dynamic Light Scattering (DLS), respectively. The results indicated that the average size of Ag nanoparticles and silica-coated Ag nanoparticles is 50 nm and 80 nm, respectively. Our TEM results indicate that the silica-shell uniformly encapsulates silver core particles. Further, a disposable electrochemical immunosensor for carcinoembryonic antigen (CEA) was proposed based on the antigen immobilized in a silica-coated silver core-shell nanoparticle film on the surface of an indium-tin-oxide (ITO) flat substrate. The morphological characteristics of the constructed biosensor were observed by scanning electron microscopy (SEM) and electrochemical methods. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed for the characterization of the proposed bioelectrode. The cyclic voltammogram appears to be more irreversible on silica coated silver core-shell nanoparticles. It is found that the fabricated immunosensor shows fast potentiometric response under the optimized conditions. The CEA could be determined in the linear range from 0.5 to 10 ng mL-1 with a detection limit of 0.01 ng mL-1 using the interface. The developed flat substrate of ITO for CEA detection (the model reagent) is a potentially promising immunosensing system, manifests good stability, and allows batch fabrication because of its economic feasibility.

Manganese Ferrite Nanoparticles (MnFe2O4): Size Dependence for Hyperthermia and Negative/Positive Contrast Enhancement in MRI

We synthesized manganese ferrite (MnFe₂O₄) nanoparticles of different sizes by varying pH during chemical co-precipitation procedure and modified their surfaces with polysaccharide chitosan (CS) to investigate characteristics of hyperthermia and magnetic resonance imaging (MRI). Structural features were analyzed by X-ray diffraction (XRD), high-resolution transmission electron microscopy (TEM), selected area diffraction (SAED) patterns, and Mössbauer spectroscopy to confirm the formation of superparamagnetic MnFe₂O₄ nanoparticles with a size range of 5–15 nm for pH of 9–12. The hydrodynamic sizes of nanoparticles were less than 250 nm with a polydispersity index of 0.3, whereas the zeta potentials were higher than 30 mV to ensure electrostatic repulsion for stable colloidal suspension. MRI properties at 7T demonstrated that transverse relaxation (T₂) doubled as the size of CS-coated MnFe₂O₄ nanoparticles tripled in vitro. However, longitudinal relaxation (T₁) was strongest for the smallest CS-coated MnFe₂O₄ nanoparticles, as revealed by in vivo positive contrast MRI angiography. Cytotoxicity assay on HeLa cells showed CS-coated MnFe₂O₄ nanoparticles is viable regardless of ambient pH, whereas hyperthermia studies revealed that both the maximum temperature and specific loss power obtained by alternating magnetic field exposure depended on nanoparticle size and concentration. Overall, these results reveal the exciting potential of CS-coated MnFe₂O₄ nanoparticles in MRI and hyperthermia studies for biomedical research.

Nanoparticles impact in biomedical waste management

Effectual management of biomedical waste is obligatory for healthy human beings and for a safe environment. Mismanagement of biomedical waste is a community health problem. Safe and persistent methods for the management of biomedical waste are of vital importance. This article reviews the classification of biomedical waste, sources, colour-coding system of biomedical waste and salient features of biomedical waste rules in 2016, and the future prospective of nanoparticles. The untreated disposal of biomedical waste is associated with a huge amount of risk, so the efficient treatment for biomedical waste is most imperative. The review also highlights the current methods for disposal of biomedical waste, biological treatments given to biomedical waste water in the effluent treatment plant, and impacts due to the current method. Management of biomedical waste is a great challenge in developed and developing countries. To manage the biomedical waste there is a need for cost-effective, ecofriendly and less contaminating approaches for a greener and safe environment. The awareness regarding waste management is of great interest not only for the community but also for associated employees.

Novel CoFe2O4@ZnO-CeO2 ternary nanocomposite: Sonochemical green synthesis using Crataegus microphylla extract, characterization and their application in catalytic and antibacterial activities

In this study, CoFe₂O₄@ZnO-CeO₂ magnetic nanocomposite (CoFe@Zn-Ce MNC) was successfully prepared by facile sonochemical method for the first time. CoFe@Zn-Ce MNC was obtained by green and cost-effective process in the presence of Crataegus microphylla (C. microphylla) fruit extract. Influence of some parameters like capping agents (C. microphylla, SDS and CTAB), sonication time (10, 30 and 60 min) and sonication power (40, 60 and 80 W) were studied to achieve optimum condition. The as-obtained products were characterized by FT-IR, FESEM, TEM, DRS, VSM, EDS, TGA and XRD analysis. Results showed that high magnetic properties (20.38 emug^-1), 70-80 nm size and spherical morphology were unique characteristics of synthesized nanocomposite. Antibacterial activity of CoFe@Zn-Ce MNC was examined against E. coli, P. aeruginoss and S. aureus bacteria. Among theme, S. aureus as gram-positive bacteria showed excellent antibacterial activity. Furthermore, photocatalytic performance of the CoFe@Zn-Ce MNC was investigated by degradation of humic acid (HA) molecules under visible and UV light irradiations. The influence of morphology of products and incorporation of cerium oxide with CoFe₂O₄@ZnO on photocatalytic activity of CoFe₂O₄@ZnO was performed. After 100 min illumination, the decomposition of HA pollutant by magnetic nanocomposite were 97.2% and 72.4% under exposure of UV and visible light irradiations, respectively. Also, CoFe@Zn-Ce MNC demonstrated high stability in the cycling decomposition experiment after six times cycling runs.

Graphene-Induced Room Temperature Ferromagnetism in Cobalt Nanoparticles Decorated Graphene Nanohybrid

Control over the magnetic interactions in magnetic nanoparticles (MNPs) is a crucial issue to the future development of nanometer-sized integrated "spintronic" applications. Here, we have developed a nanohybrid structure to achieve room temperature ferromagnetism, via a facile, effective, and reproducible solvothermal synthesis method. The plan has been put onto cobalt (Co) NPs, where the growth of Co NPs on the surface of reduced graphene oxide (rGO) nanosheets switches the magnetic interactions from superparamagnetic to ferromagnetic at room temperature. Switching-on ferromagnetism in this nanohybrid may be due to the hybridization between unsaturated 2p_z orbitals of graphene and 3d orbitals of Co, which promotes ferromagnetic long-range ordering. The ferromagnetic behavior of Co-rGO nanohybrid makes it excellent material in the field of spintronics, catalysis, and magnetic resonance imaging.

Influence of trivalent Cr ion substitution on the physicochemical, optical, electrical, and dielectric properties of sprayed NiFe2O4 spinel-magnetic thin films

In this study, we mainly investigated the effects of trivalent Cr ion substitution on the properties of nickel ferrite (NCF) spinel-thin films. The as-prepared spinel thin films were characterized by thermogravimetry-differential thermal analysis (TGA-DTA) to comprehensively examine their phase transition. X-ray diffraction (XRD) analysis revealed that the prepared films have a single-phase face-centered cubic crystal structure. A Raman study confirmed the arrangement of the inverse-cubic spinel structure of these spinel-thin films. Field-emission scanning electron microscopy (FE-SEM) images verified the slight agglomeration of particles. Similarly, transmission electron microscopy (TEM) images together with selected area electron diffraction (SAED) patterns supported the XRD results. PL spectra showed enhanced near band emission (NBE) intensity due to the passivation of oxygen vacancies by Cr³⁺ substitution. The DC electrical resistivity (ρ) increases from 1.4 × 10^-6 Ω cm to 4.42 × 10^-6 Ω cm at room temperature. Dielectric parameters were studied as a function of frequency in the range of 1-10 MHz at 300 K, and these parameters decreased with the increasing Cr³⁺ ion concentration in the spinel-thin films. The obtained results indicate the applicability of the fabricated thin films in high-frequency electronic devices.

Combining cobalt ferrite and graphite with cellulose nanocrystals for magnetically active and electrically conducting mesoporous nanohybrids

Free-standing mesoporous membranes based on cellulose nanocrystals (CNCs) are fabricated upon the incorporation of cobalt ferrite (CoFe₂O₄) and graphite nanoparticles at concentrations up to 20 wt % through a soft-templating process. Scanning electron microscopy (SEM) and N₂ adsorption-desorption isotherms reveal the development of highly-porous interconnected random 3D structure with surface areas up to 193.9 m² g^-1. Thermogravimetric analysis (TGA) shows an enhanced thermal stability thanks to the formation of a tortuous network limiting the hindrance of degradation by-products. Vibrating sample magnetometer (VSM) reveals a maximum magnetization saturation of 8.77 emu·g^-1 with materials having either ferromagnetic or diamagnetic behaviour upon the incorporation of CoFe₂O₄ and graphite, respectively. Four-point-probe measurements display a maximum electrical conductivity of 9.26 ± 0.04 S·m^-1 when graphite is incorporated into CNCs. A proof of concept for the applicability of synthesized nanohybrids for environmental remediation is provided, presenting the advantage of their easy recovery using external magnetic fields.

Nanomaterials for removal of waterborne pathogens

As the nanotechnological applications have taken over in different fields, their applications for water and wastewater treatment is also surfacing as a fast-developing and very promising area. Recent advancements in nanotechnological science and engineering advise that many of the waterborne pathogens could be culminated or debilitated using nanobiosorbents, nanocatalysts, bioactive nanoparticles, nanostructured catalytic membranes, nanobioreactors, nanoparticle-enhanced filtration among other products, and processes resulting from the development of nanotechnology. A detailed insight has been provided for advanced techniques such as photochemical (photocatalytic and advanced oxidation processes) applications of metal oxide nanoparticles, nanomembrane technology, bioinspired nanomaterials, and nanotechnological innovations (nano-Ag, fullerenes, nanotubes, and molecularly imprinted polymers, etc.), which prove to be highly potential as well as promising and cost-effective. However, there are still some shortcomings and challenges that must be overcome which will be looked upon in this chapter.

Recent advancements in manganite perovskites and spinel ferrite-based magnetic nanoparticles for biomedical theranostic applications

Recently, magnetic nanoparticles (MNPs) based on manganite perovskites (La_1-xSr_xMnO₃ or LSMO) and/or spinel ferrites (i.e. SPFs with the formula MFe₂O₄; M=Co, Mg, Mn, Ni and Zn and mixed SPFs (e.g. Co-Zn, Mg-Mn, Mn-Zn and/or Ni-Zn)) have garnered great interest in magnetic hyperthermia therapy (MHT) as heat-inducing agents due to their tuneable magnetic properties including Curie temperature (T _c) to generate controllable therapeutic temperatures (i.e. 42 °C-45 °C)-under the application of an alternating magnetic field (AMF)-for the treatment of cancer. In addition, these nanoparticles are also utilized in magnetic resonance imaging (MRI) as contrast-enhancing agents. However, the employment of the LSMO/SPF-based MNPs in these MHT/MRI applications is majorly influenced by their inherent properties, which are mainly tuned by the synthesis factors. Therefore, in this review article, we have systematically discussed the significant chemical methods used to synthesize the LSMO/SPF-based MNPs and their corresponding intrinsic physicochemical properties (size/shape/crystallinity/dispersibility) and/or magnetic properties (including saturation magnetization (M _s)/T _c). Then, we have analyzed the usage of these MNPs for the effective imaging of cancerous tumors via MRI. Finally, we have reviewed in detail the heating capability (in terms of specific absorption rate) of the LSMO/SPF-based MNPs under calorimetric/biological conditions for efficient cancer treatment via MHT. Herein, we have mainly considered the significant parameters-such as size, surface coating (nature and amount), stoichiometry, concentration and the applied AMFs (including amplitude (H) and frequency (f))-that influence the heat induction ability of these MNPs.

Structural, Morphological, Magnetic and Self-Heating Studies of One-Step Polyol Synthesized Manganese Ferrite (MnFe2O4) Nanoparticles

In this paper, uniform and superparamagnetic nanoparticles have been prepared using one-step polyol synthesis method. Structural, morphological and magnetic properties of obtained MnFe2O4 nanoparticles have been investigated by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM) and thermogravimetric analysis (TGA) techniques. Structural investigation showed that the average crystallite size of obtained nanoparticles was about 10[Formula: see text]nm. Magnetic study revealed that the nanoparticles were superparamagnetic at room temperature with magnetization 67[Formula: see text]emu/g at room temperature. The self-heating characteristics of synthesized MnFe2O4 nanoparticles were studied by applying external AC magnetic field of 167.6 to 335.2[Formula: see text]Oe at a fixed frequency of 265[Formula: see text]kHz. The SAR values of MnFe2O4 nanoparticles were calculated for 2, 5, 10[Formula: see text]mg[Formula: see text]mL[Formula: see text] concentrations and it is observed that the threshold hyperthermia temperature is achieved for all concentrations.

Synthesis and characterization of zinc oxide nanoparticles by using polyol chemistry for their antimicrobial and antibiofilm activity

The present investigation deals with facile polyol mediated synthesis and characterization of ZnO nanoparticles and their antimicrobial activities against pathogenic microorganisms. The synthesis process was carried out by refluxing zinc acetate precursor in diethylene glycol(DEG) and triethylene glycol(TEG) in the presence and in the absence of sodium acetate for 2 h and 3 h. All synthesized ZnO nanoparticles were characterized by X-ray diffraction (XRD), UV visible spectroscopy (UV), thermogravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy(FESEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) technique. All nanoparticles showed different degree of antibacterial and antibiofilm activity against Gram-positive Staphylococcus aureus (NCIM 2654)and Gram-negative Proteus vulgaris (NCIM 2613). The antibacterial and antibiofilm activity was inversely proportional to the size of the synthesized ZnO nanoparticles. Among all prepared particles, ZnO nanoparticles with least size (~ 15 nm) prepared by refluxing zinc acetate dihydrate in diethylene glycol for 3 h exhibited remarkable antibacterial and antibiofilm activity which may serve as potential alternatives in biomedical application.

Enzyme mimetic activities of spinel substituted nanoferrites (MFe2O4): A review of synthesis, mechanism and potential applications

Recently, the intrinsic enzyme-like activities of some nanoscale materials known as "nanozymes" have become a growing area of interest. Nanosized spinel substituted ferrites (SFs) with general formula of MFe₂O₄, where M represents a transition metal, are among a group of magnetic nanomaterials attracting researchers' enormous attention because of their excellent catalytic performance, biomedical applications and capability for environmental remediation. Due to their unique nanoscale physical-chemical properties, they have been used to mimic the catalytic activity of natural enzymes such as peroxidases, oxidases and catalases. In addition, various nanocomposite materials based on SFs have been introduced as novel artificial enzymes. This review mainly highlights the synthetic approaches for newly developed SF-nanozymes and also the structural/experimental factors that are effective on the kinetics and catalytic mechanisms of enzyme-like reactions. SF-nanozymes have been found potentially capable of being applied in various fields such as enzyme-free immunoassays and biosensors for colorimetric detection of biological molecules. Therefore, the application of SF nanoparticles, as efficient enzyme mimetics have been detailed discussed.

CuI incorporated cobalt ferrite nanoparticles as a magnetically separable catalyst for oxidative amidation reaction

A Cu-incorporated magnetic nanocatalyst has been developed for oxidative amidation of aryl aldehydes with 2-aminopyridine in the presence of TBHP.

One-pot synthesis of monodisperse CoFe2O4@Ag core-shell nanoparticles and their characterization

In recent years, monodispersed magnetic nanoparticles with a core/shell structure are expected for their wide applications including magnetic fluid, recoverable catalysts, and biological analysis. However, their synthesis method needs numerous processes such as solvent substitution, exchange of protective agents, and centrifugation. A simple and rapid method for the synthesis of monodispersed core-shell nanoparticles makes it possible to accelerate their further applications. This paper describes a simple and rapid one-pot synthesis of core (CoFe₂O₄)-shell (Ag) nanoparticles with high monodispersity. The synthesized nanoparticles showed plasmonic light absorption owing to the Ag shell. Moreover, the magnetic property of the nanoparticles had a soft magnetic behavior at room temperature and a hard magnetic behavior at 5 K. In addition, the nanoparticles showed high monodispersity with a low polydispersity index (PDI) value of 0.083 in hexane.

Comprehensive cytotoxicity studies of superparamagnetic iron oxide nanoparticles

Recently lots of efforts have been taken to develop superparamagnetic iron oxide nanoparticles (SPIONs) for biomedical applications. So it is utmost necessary to have in depth knowledge of the toxicity occurred by this material. This article is designed in such way that it covers all the associated toxicity issues of SPIONs. It mainly emphasis on toxicity occurred at different levels including cellular alterations in the form of damage to nucleic acids due to oxidative stress and altered cellular response. In addition focus is been devoted for in vitro and in vivo toxicity of SPIONs, so that a better therapeutics can be designed. At the end the time dependent nature of toxicity and its ultimate faith inside the body is being discussed.

Development of high-performance supercapacitor electrode derived from sugar industry spent wash waste

This study aims at developing supercapacitor materials from sugar and distillery industry wastes, thereby mediating waste disposal problem through reuse. In a two-step process, biomethanated spent wash (BMSW) was acid treated to produce solid waste sludge and waste water with significantly reduced total organic carbon (TOC) and biological oxygen demand (BOD) content. Further, waste sludge was directly calcined in presence of activating agent ZnCl₂ in inert atmosphere resulting in high surface area (730-900m²g^-1) carbon of unique hexagonal morphology. Present technique resulted in achieving two-faceted target of liquid-solid waste remediation and production of high-performance carbon material. The resulted high surface area carbon was tested in both three and two electrode systems. Electrochemical tests viz. cyclic voltammetry, galvanostatic charge-discharge and impedance measurement were carried out in aqueous KOH electrolyte yielding specific capacitance as high as 120Fg^-1, whereas all solid supercapacitor devised using PVA/H₃PO₄ polyelectrolyte showed stable capacitance of 105Fg^-1 at 0.2Ag^-1. The presence of transition metal particles and hetero-atoms on carbon surface were confirmed by XPS, EDX and TEM analysis which enhanced the conductivity and imparted pseudocapacitance to some extent into the working electrode. The present study successfully demonstrated production of high-performance electrode material from dirtiest wastewater making process green, sustainable and economically viable.

Synthesis and characterization of pHLIP® coated gold nanoparticles

Novel approaches in synthesis of spherical and multispiked gold nanoparticles coated with polyethylene glycol (PEG) and pH Low Insertion Peptide (pHLIP^®) were introduced. The presence of a tumor-targeting pHLIP^® peptide in the nanoparticle coating enhances the stability of particles in solution and promotes a pH-dependent cellular uptake. The spherical particles were prepared with sodium citrate as a gold reducing agent to form particles of 7.0±2.5 nm in mean metallic core diameter and ∼43 nm in mean hydrodynamic diameter. The particles that were injected into tumors in mice (21 µg of gold) were homogeneously distributed within a tumor mass with no staining of the muscle tissue adjacent to the tumor. Up to 30% of the injected gold dose remained within the tumor one hour post-injection. The multispiked gold nanoparticles with a mean metallic core diameter of 146.0±50.4 nm and a mean hydrodynamic size of ~161 nm were prepared using ascorbic acid as a reducing agent and disk-like bicelles as a template. Only the presence of a soft template, like bicelles, ensured the appearance of spiked nanoparticles with resonance in the near infrared region. The irradiation of spiked gold nanoparticles by an 805 nm laser led to the time- and concentration-dependent increase of temperature. Both pHLIP^® and PEG coated gold spherical and multispiked nanoparticles might find application in radiation and thermal therapies of tumors.

•

pHLIP^®-PEG coated pH-sensitive gold spherical nanoparticles were synthesized.

•

30% of the injected gold dose remained within the tumor one hour post-injection.

•

pHLIP^®-PEG coated pH-sensitive gold multispiked nanoparticles were synthesized.

•

Bicelles were used as a soft template to obtain multispiked nanoparticles.

•

Temperature increases after 805 nm irradiation of spiked gold nanoparticles.

Plasmonic/Magnetic Multifunctional nanoplatform for Cancer Theranostics

A multifunctional magneto-plasmonic CoFe2O4@Au core-shell nanoparticle was developed by iterative-seeding based method. This nanocargo consists of a cobalt ferrite kernel as a core (Nk) and multiple layers of gold as a functionalizable active stratum, (named as Nk@A after fifth iteration). Nk@A helps in augmenting the physiological stability and enhancing surface plasmon resonance (SPR) property. The targeted delivery of Doxorubicin using Nk@A as a nanopayload is demonstrated in this report. The drug release profile followed first order rate kinetics optimally at pH 5.4, which is considered as an endosomal pH of cells. The cellular MR imaging showed that Nk@A is an efficient T2 contrast agent for both L6 (r2-118.08 mM-1s-1) and Hep2 (r2-217.24 mM-1s-1) cells. Microwave based magnetic hyperthermia studies exhibited an augmentation in the temperature due to the transformation of radiation energy into heat at 2.45 GHz. There was an enhancement in cancer cell cytotoxicity when hyperthermia combined with chemotherapy. Hence, this single nanoplatform can deliver 3-pronged theranostic applications viz., targeted drug-delivery, T2 MR imaging and hyperthermia.

Role of functionalization: strategies to explore potential nano-bio applications of magnetic nanoparticles

Strategies to bridge the gap between magnetic nanoparticles for their nano bio applications.

Innovative Developments in Bacterial Detection with Magnetic Nanoparticles

It has been seen from the last decade that many bacterial strains are becoming insensitive to conventional detection techniques and it has its own limitations. Current developments in nanoscience and nanotechnology have expanded the ability to design and construct nanomaterials with targeting, therapeutic, and diagnostic functions. These multifunctional nanomaterials have attracted researchers, to be used as the promising tool for selective bacterial sensing applications. An important advantage of using magnetic nanoparticles to capture bacteria is the simple separation of bacteria from biological samples using magnets. This review includes significance of magnetic nanoparticles in bacterial detection. Relevant to topic, properties, designing strategies for magnetic nanoparticle, and innovative techniques used for detection are discussed. This review provides the readers how magnetic properties of nanoparticles can be utilized systematically for bacterial identification.

Cancer cell extinction through a magnetic fluid hyperthermia treatment produced by superparamagnetic Co–Zn ferrite nanoparticles

TEG mediated synthesis of CZF MNPs for cancer cell extinction by using magnetic fluid hyperthermia therapy.