Immobilized Au nanoparticles on chitosan-biguanidine modified Fe3O4 nanoparticles and investigation of its anti-human lung cancer activity

In current nanoscience bioengineered magnetic nanoparticles (NPs) have come into prominence with considerable impact. These advanced functional materials find outstanding applications in chemical science in catalysis, environmental issues, sensing etc, as well as in biology as drug delivery agent, chemical therapeutics and others. We have been prompted to architect and synthesize a novel Au NP adorned over chitosan-biguanidine polyplex modified core–shell type magnetic nanocomposite (Fe₃O₄/CS-biguanidine/Au NPs). The bioshells facilitate to protect the core ferrite NPs as well as provides stability to the synthesized Au NPs by capping. The material was characterized using different analytical techniques like Fourier Transformed Infra-Red spectroscopy (FT-IR), Inductively Coupled Plasma-Optical Emission Microscopy (ICP-OES), Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray spectroscopy (EDX), Transmission Electron Microscopy (TEM), Vibrating Sample Magnetometer (VSM) and X-ray Diffraction (XRD) studies. We explored the biological application of the nanocomposite in determining cytotoxicity of three adenocarcinoma cell lines (PC-14, LC-2/ad, HLC-1) through the MTT assay. The material showed very good activity by exhibiting very low % cell viability over the cell lines dose-dependently. The IC50 of Fe₃O₄/CS-biguanidine/Au NPs were observed 503, 398 and 475 µg/mL respectively against the three cell lines. The best output was observed at a concentration of 1000 µg/mL of catalyst in terms of cytotoxicity and inhibition of lung cancer growth. The anti-cancer potential was found in close relation to their antioxidant potential.     

Nanotheranostic fabrication of iron oxide for rapid photocatalytic degradation of organic dyes and antifungal potential

This research work includes the fabrication of iron oxide nanoparticles (Fe₂O₃ NPs) by green construction approach using Wisteria sinensis leaves extract. Due to its eco-friendly approach, the synthesis of iron oxide NPs (Fe₂O₃ NPs) using various plant sources, such as plant parts, and microbial cells have gained a lot of attention in recent years. Cost-effectiveness and ease of availability make Wisteria sinensis leaves extract a potential candidate for the construction of iron oxide NPs. The various key features like biocompatibility, non-toxicity capping, and stabilizing agents present in biological sources are advantageous for usage in a variety of applications. The phytoconstituents present in the leaf extract of Wisteria sinensis serve as reducing and stabilizing agents. The biologically fabricated (Fe₂O₃ NPs) were analyzed using FT-IR, XRD, UV–vis spectroscopy, and SEM. In the present work, the antioxidant and photocatalytic dye degradation efficiency of Fe₂O₃ NPs has been studied. The dye degradation efficiency of methylene blue dye was found to be 87% at 180 min upon exposure to sunlight. The capacity of Fe₂O₃ NPs to scavenge 2,2-diphenyl-1-picrylhydrazyl hydrate free radicals (DPPH) was examined using a UV–Vis spectrophotometer. The study compared the radical scavenging activity (RSA) of Fe₂O₃ nanoparticles (NPs) with that of the standard antioxidant ascorbic acid. The results demonstrated that Fe₂O₃ NPs have a greater ability to scavenge radicals than ascorbic acid. The half-maximal inhibitory concentration (IC50) of Fe₂O₃ NPs was observed to range from 0.12 to 0.17. Furthermore, Fe₂O₃ NPs displayed the highest antifungal activity, with an inhibition zone of 26.8 mm against F. oxysporum. These findings suggest that the biologically synthesized Fe₂O₃ NPs possess potent antimicrobial and dye degradation properties.     

Synthesis of Co/MFe2O4 (M=Fe, Mn) core/shell nanocomposite particles

Monodispersed cobalt nanoparticles (NPs) with controllable size (8–14 nm) have been synthesized using thermal decomposition of dicobaltoctacarbonyl in organic solvent. The as-synthesized high magnetic moment (125 emu/g) Co NPs are dispersible in various organic solvents, and can be easily transferred into aqueous phase by surface modification using phospholipids. However, the modified hydrophilic Co NPs are not stable as they are quickly oxidized, agglomerated in buffer. Co NPs are stabilized by coating the MFe₂O₄ (M=Fe, Mn) ferrite shell. Core/shell structured bimagnetic Co/MFe₂O₄ nanocomposites are prepared with tunable shell thickness (1–5 nm). The Co/MFe₂O₄ nanocomposites retain the high magnetic moment density from the Co core, while gaining chemical and magnetic stability from the ferrite shell. Compared to Co NPs, the nanocomposites show much enhanced stability in buffer solution at elevated temperatures, making them promising for biomedical applications.     

Pectin mediated green synthesis of Fe3O4/Pectin nanoparticles under ultrasound condition as an anti-human colorectal carcinoma bionanocomposite

This work described the one-pot synthesis of apple pectin encapsulated Fe₃O₄ nanoparticles (Fe₃O₄/Pectin NPs) which is prepared by co-precipitation of Fe(II/(III) ions in alkaline solution mediated by pectin under ultrasound condition. This process led to formation of magnetic nanoparticles within the network of pectin. Physicochemical characterization of the as-synthesized Fe₃O₄/Pectin NPs was carried out through electron microscopy (SEM and TEM), energy dispersive X-ray spectroscopy (EDX), vibrating sample magnetometer (VSM) and X-ray diffraction (XRD). The in vitro cytotoxic and anti-colorectal cancer effects of biologically synthesized Fe₃O₄/Pectin NPs against Ramos.2G6.4C10, HCT-8 [HRT-18], HCT 116, and HT-29 cancer cell lines were assessed. The anti-colorectal cancer properties of the Fe₃O₄/Pectin NPs could significantly remove Ramos.2G6.4C10, HCT-8 [HRT-18], HCT 116, and HT-29 cancer cell lines in a time and concentration-dependent manner by MTT assay. The IC₅₀ of the Fe₃O₄/Pectin NPs were 317, 337, 187, and 300 µg/mL against Ramos.2G6.4C10, HCT-8 [HRT-18], HCT 116, and HT-29 cancer cell lines. The antioxidant activity of Fe₃O₄/Pectin NPs was determined by DPPH method. The Fe₃O₄/Pectin NPs showed the high antioxidant activity according to the IC₅₀ value. It seems that the anti-human colorectal cancer effect of recent nanoparticles is due to their antioxidant effects.     

Physiochemical properties and novel biological applications of Callistemon viminalis‐mediated α‐Cr2O3 nanoparticles

We report an eco‐friendly synthesis of α‐Cr₂O₃ nanoparticles (NPs) using Callistemon viminalis (Bottle Brush) flower extracts as an efficient reducing and capping agent. NPs of sizes 15 nm and 17 nm were synthesized by annealing them at 400°C and 500°C, respectively, which were characterized by X‐ray diffraction, UV–Vis, Fourier transform‐infrared, high‐resolution‐transmission electron microscopy/scanning electron microscopy, SAED, energy‐dispersive X‐ray spectroscopy and SQUID. Microplate‐based assay was used for examining antibacterial potential against 12 pathogenic bacterial strains, and their minimum inhibitory concentrations were calculated. MTT cytotoxic assay was accomplished on Leishmania tropica amastigotes and promastigotes, which revealed IC₅₀ values of 44 μg/ml and 10.56 μg/ml, respectively. An IC₅₀ value of 46.32 μg/ml was obtained for HepG2 cancer cells. Enzyme inhibition studies indicated good acetylcholinesterase, moderate butyrylcholinesterase and low alpha‐glucosidase inhibition. Hemolytic assay indicated hemocompatibility at low concentration. In addition, good DPPH radical scavenging and moderate reducing power and total antioxidant potential was revealed by α‐Cr₂O₃ NPs.     

Facile synthesis of multifunctional multiwalled carbon nanotubes/Fe3O4 nanoparticles/polyaniline composite nanotubes

With an average diameter of 100-150 nm, composite nanotubes of polyaniline (PANI)/multiwalled carbon nanotubes (MWNTs) containing Fe₃O₄ nanoparticles (NPs) were synthesized by a two-step method. First, we synthesized monodispersed Fe₃O₄ NPs (d=17.6 nm, σ=1.92 nm) on the surface of MWNTs and then decorated the nanocomposites with a PANI layer via a self-assembly method. SEM and TEM images indicated that the obtained samples had the morphologies of nanotubes. The molecular structure and composition of MWNTs/Fe₃O₄ NPs/PANI nanotubes were characterized by Fourier transform infrared spectra (FTIR), energy dispersive X-ray spectrometry (EDX), X-ray photoelectron spectra (XPS), X-ray diffraction (XRD) and Raman spectra. UV-vis spectra confirmed the existence of PANI and its response to acid and alkali. As a multifunctional material, the conductivity and magnetic properties of MWNTs/Fe₃O₄ NPs/PANI composites nanotubes were also investigated.     

Covalent bonding of magnetic Fe3O4 nanoparticles to aminopropyl‐functionalized magnesium phyllosilicate clay: Synthesis and cytotoxic potential investigation

Stable water dispersion of Fe₃O₄ magnetic nanoparticles (NPs) were successfully synthesized by using 3‐glycidoxypropyltrimethoxysilane (GPTMS) and Mg‐phyllo (organo) silicate known as aminoclay (AC) containing pendant amino groups with the approximate composition (R₈Si₈Mg₆O₁₆(OH)₄, R = CH₂CH₂CH₂NH₂). The Fe₃O₄‐GPTMS magnetic NPs with an epoxy functional group are suitable for forming a covalent bond with the amine group of aminoclay in an epoxy ring opening reaction. Appropriate Fe₃O₄‐GPTMS‐aminoclay (FG‐AC) magnetic composite are promising carriers for the targeting and delivery of platinum‐based anticancer drugs. Analysis of the cytotoxicity of the nanostructures on a K562 leukemia cell line using a colorimetery assay shows that both the FG‐AC and cis‐platin/FG‐AC magnetic composite were biocompatible. The nanostructures characterizations were investigated by Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy and energy dispersive analysis of X‐ray techniques. Magnetic measurement revealed that the saturated magnetization of the FG‐AC nanocomposite reached 7.6 emu/g and showed the characteristics of magnetism.     

Synthesis of Fe3O4@SiO2-Au/Cu magnetic nanoparticles and its efficient catalytic performance for the Ullmann coupling reaction of bromamine acid

Over bimetallic Au/Cu catalyst supported on magnetic Fe₃O₄ nanoparticles, water-mediated bromamine acid could be selectively converted into 4,4'-diamino-1,1'-dianthraquinonyl-3,3'-disulfonic acid (DAS) with a yield of 88.67%. The magnetic catalyst could be readily separated and reused.     

Preparation of chitosan functionalized end‐capped Ag‐NPs and composited with Fe3O4‐NPs: Controlled release to pH‐responsive delivery of progesterone and antibacterial activity against pseudomonas aeruginosa (PAO‐1)

In this work, functionalized chitosan end‐capped Ag nanoparticles (NPs) and composited with Fe₃O₄‐NPs was prepared as pH‐responsive controlled release carrier for gastric‐specific drug delivery. The structure of prepared material was characterized by FE‐SEM, XRD, EDS and FT‐IR analysis. The loading behavior of the progesterone onto this novel material was studied in aqueous medium at 25°C and their release was followed spectrophotometrically at 37°C in seven different buffer solutions (pH 1.2, 2.2, 3.2, 4.2, 5.2, 6.2 and 7.2) to simulate intestine and gastric media which experimental results reveal more release rate in pH 1.2 (gastric medium) with respect to other buffers. This observation is attributed to dependency of the CS‐IMBDO‐Ag‐Fe₃O₄‐NPs and progesterone structure with buffer pH that candidate this new material as prospective pH‐sensitive carrier for gastric‐targeted drug delivery. On the other hand, the antibacterial properties of this material against gram‐negative bacterium pseudomonas aeruginosa (PAO‐1) in agar plates was studied and accordingly based on broth micro dilution the minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) with respect to standard CLSI in different concentrations of CS‐IMBDO‐Ag‐Fe₃O₄‐NPs was calculated. The results reveal that MIC and MBC values are 50 and 1250 μg/mL, respectively. In addition, extracts of Portulaca oleracea leaves was prepared and its antibacterial activity in single and binary system with CS‐IMBDO‐Ag‐Fe₃O₄‐NPs as synergies effect against PAO‐1 was tested and results shown that these materials have significant synergistic effect for each other.     

Environmentally friendly and highly efficient synthesis of benzoxazepine and malonamide derivatives using HPA/TPI‐Fe3O4 nanoparticles as recoverable catalyst in aqueous media

A magnetic inorganic–organic nanohybrid material (HPA/TPI‐Fe₃O₄ NPs) was produced as an efficient, highly recyclable and eco‐friendly catalyst for the one‐pot multi‐component synthesis of malonamide and 2,3,4,5‐tetrahydrobenzo[b ][1,4]oxazepine derivatives with high yields in short reaction times (25–35 min) in aqueous media at room temperature. The nanohybrid catalyst was prepared by the chemical anchoring of H₆P₂W₁₈O₆₂ onto the surface of modified Fe₃O₄ nanoparticles (NPs) with N ‐[3‐(triethoxysilyl)propyl]isonicotinamide (TPI) linker. The magnetic recoverable catalyst was easily recycled at least ten times without any loss of catalytic activity.     

Magnetic Resonance and Mössbauer Studies of Superparamagnetic γ‐Fe2O3 Nanoparticles Encapsulated into Liquid‐Crystalline Poly(propylene imine) Dendrimers

We present the first results of electron magnetic resonance (EMR) and Mössbauer spectroscopy studies of γ‐Fe₂O₃ nanoparticles (NPs) incorporated into liquid‐crystalline, second‐generation dendrimers. The mean size of NPs formed in the dendrimers was around 2.5 nm. A temperature‐driven transition from superparamagnetic to ferrimagnetic resonance was observed for the sample. Low‐temperature blocking of the NP magnetic moments has been clearly evidenced in the integrated EMR line intensity and the blocking temperature was about 60 K. The physical parameters of magnetic NPs (magnetic moment, effective magnetic anisotropy) have been determined from analyses of the EMR data. The effective magnetic anisotropy constant is enhanced relative to bulk γ‐Fe₂O₃ and this enhanced value is associated with the influence of the surface and shape effects. The angular dependence of the EMR signal position for the field‐freezing sample from liquid‐crystalline phase showed that NPs possessed uniaxial anisotropy, in contrast to bulk γ‐Fe₂O₃. Mössbauer spectroscopy determined that fabricated NPs consisted of an α‐Fe core and a γ‐Fe₂O₃ shell.     

Iron Oxide Nanoparticles: Biosynthesis,Magnetic Behavior,Cytotoxic Effect

Iron oxide nanoparticles have attracted much attention because of their superparamagnetic properties and their potential applications in many fields such as magnetic storage devices, catalysis, sensors, superparamagnetic relaxometry (SPMR), and high-sensitivity biomolecule magnetic resonance imaging (MRI) for medical diagnosis and therapeutics. In this study, iron oxide nanoparticles (Fe₂O₃ NPs) have been synthesized using a taranjabin (camelthorn or persian manna) aqueous solution. The synthesized Fe₂O₃ NPs were identified through powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), field energy scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX), vibrating-sample magnetometer (VSM) and Raman technics. The results show that the nanoparticles have a hexagonal structure with 20 to 60 nm in size. The cytotoxic effect of the synthesized nanoparticles has been tested upon application against lung cancer cell (A549) lines. It was found that there is no cytotoxic activity at lower concentrations of 200 μg/mL. The ability of the synthesized nanoparticles for lead removal in wastewaters was tested. Results show that highest concentration of adsorbent (50 mg/L) has maximum removal efficiency (96.73 %). So, synthesized Fe₂O₃ NPs can be a good candidate to use as heavy metals cleaner from contaminated waters.     

Supercritical Carbon Dioxide Assisted Deposition of Fe3O4 Nanoparticles on Hierarchical Porous Carbon and Their Lithium‐Storage Performance

A composite of highly dispersed Fe₃O₄ nanoparticles (NPs) anchored in three‐dimensional hierarchical porous carbon networks (Fe₃O₄/3DHPC) as an anode material for lithium‐ion batteries (LIBs) was prepared by means of a deposition technique assisted by a supercritical carbon dioxide (scCO₂)‐expanded ethanol solution. The as‐synthesized Fe₃O₄/3DHPC composite exhibits a bimodal porous 3D architecture with mutually connected 3.7 nm mesopores defined in the macroporous wall on which a layer of small and uniform Fe₃O₄ NPs was closely coated. As an anode material for LIBs, the Fe₃O₄/3DHPC composite with 79 wt % Fe₃O₄ (Fe₃O₄/3DHPC‐79) delivered a high reversible capacity of 1462 mA h g^?1 after 100 cycles at a current density of 100 mA g^?1, and maintained good high‐rate performance (728, 507, and 239 mA h g^?1 at 1, 2, and 5 C, respectively). Moreover, it showed excellent long‐term cycling performance at high current densities, 1 and 2 A g^?1. The enhanced lithium‐storage behavior can be attributed to the synergistic effect of the porous support and the homogeneous Fe₃O₄ NPs. More importantly, this straightforward, highly efficient, and green synthetic route will definitely enrich the methodologies for the fabrication of carbon‐based transition‐metal oxide composites, and provide great potential materials for additional applications in supercapacitors, sensors, and catalyses.     

3D Porous Carbon Framework Stabilized Ultra‐Uniform Nano γ‐Fe2O3: A Useful Catalyst System

We present a novel strategy for the scalable fabrication of γ‐Fe₂O₃@3DPCF, a three‐dimensional porous carbon framework (PCF) anchored ultra‐uniform and ultra‐stable γ‐Fe₂O₃ nanocatalyst. The γ‐Fe₂O₃@3DPCF nanocomposites were facilely prepared with the following route: condensation of iron(III) acetylacetonate with acetylacetonate at room temperature to form the polymer precursor (PPr), which was carbonized subsequently at 800 °C. The homogeneous aldol condensation offered an ultra‐uniform distribution of iron, so that the γ‐Fe₂O₃ nanoparticles (NPs) were uniformly distributed in the 3D carbon architecture with the average size of approximate 20 nm. The Fe₂O₃ NPs were capped with carbon, so that the iron oxide maintained its γ‐phase instead of the more stable α‐phase. The nanocomposite was an excellent catalyst for the reduction of nitroarene; it gave >99 % conversion and 100 % selectivity for the reduction of nitroarenes to the corresponding anilines at 100 °C. The fabrication of the γ‐Fe₂O₃@3DPCF nanocatalyst represents a green and scalable method for the synthesis of novel carbon‐based metal oxide nanostructures.     

Green synthesis of reduced graphene oxide/Fe3O4/Ag ternary nanohybrid and its application as magnetically recoverable catalyst in the reduction of 4‐nitrophenol

Materials having both magnetic and catalytic properties have shown great potential for practical applications. Here, a reduced graphene oxide/iron oxide/silver nanohybrid (rGO/Fe₃O₄/Ag NH) ternary material was prepared by green synthesis of Ag on pre‐synthesized rGO/Fe₃O₄. The as‐prepared rGO/Fe₃O₄/Ag NH was characterized using Fourier transform infrared spectroscopy, X‐ray diffractometry, Raman spectroscopy, vibrating sample magnetometry, transmission electron microscopy and energy‐dispersive X‐ray spectroscopy. rGO sheets were covered with Fe₃O₄ (8–16 nm) and Ag (18–40 nm) nanoparticles at high densities. The mass percentages were 13.47% (rGO), 62.52% (Fe₃O₄) and 24.01% (Ag). rGO/Fe₃O₄/Ag NH exhibited superparamagnetic behavior with high saturated magnetization (29 emu g⁻¹ at 12 kOe), and efficiently catalyzed the reduction of 4‐nitrophenol (4‐NP) with a rate constant of 0.37 min⁻¹, comparable to those of Ag‐based nanocatalysts. The half‐life of 4‐NP in the presence of rGO/Fe₃O₄/Ag NH was ca 1.86 min. rGO/Fe₃O₄/Ag NH could be magnetically collected and reused, and retained a high conversion efficiency of 94.4% after the fourth cycle. rGO/Fe₃O₄/Ag NH could potentially be used as a magnetically recoverable catalyst in the reduction of 4‐NP and environmental remediation.     

General Preparation of Heme Protein Functional Fe3O4@Au‐Nps Magnetic Nanocomposite for Sensitive Detection of Hydrogen Peroxide

Stable magnetic nanocomposite of gold nanoparticles (Au‐NPs) decorating Fe₃O₄ core was successfully synthesized by the linker of Boc‐L‐cysteine. Transmission electron microscope (TEM), energy dispersive X‐ray spectroscopy (EDX) and cyclic voltammograms (CV) were performed to characterize the as‐prepared Fe₃O₄@Au‐Nps. The results indicated that Au‐Nps dispersed homogeneously around Fe₃O₄ with the ratio of Au to Fe₃O₄ nanoparticles as 5–10/1 and the apparent electrochemical area as 0.121 cm². After self‐assembly of hemoglobin (Hb) on Fe₃O₄@Au‐Nps by electrostatic interaction, a hydrogen peroxide biosensor was developed. The Fe₃O₄@Au‐Nps/Hb modified GCE exhibited fast direct electron transfer between heme center and electrode surface with the heterogeneous electron transfer rate constant (Ks ) of 3.35 s⁻¹. Importantly, it showed excellent electrocatalytic activity towards hydrogen peroxide reduction with low detection limit of 0.133 μM (S /D =3) and high sensitivity of 0.163 μA μM⁻¹, respectively. At the concentration evaluated, the interfering species of glucose, dopamine, uric acid and ascorbic acid did not affect the determination of hydrogen peroxide. These results demonstrated that the introduction of Au‐Nps on Fe₃O₄ not only stabilized the immobilized enzyme but also provided large surface area, fast electron transfer and excellent biocompatibility. This facile nanoassembly protocol can be extended to immobilize various enzymes, proteins and biomolecules to develop robust biosensors.     

Facile deposition of gold nanoparticles on core–shell Fe3O4@polydopamine as recyclable nanocatalyst

A simple and green method for the controllable synthesis of core–shell Fe₃O₄ polydopamine nanoparticles (Fe₃O₄@PDA NPs) with tunable shell thickness and their application as a recyclable nanocatalyst support is presented. Magnetite Fe₃O₄ NPs formed in a one-pot process by the hydrothermal approach with a diameter of ∼240 nm were coated with a polydopamine shell layer with a tunable thickness of 15–45 nm. The facile deposition of Au NPs atop Fe₃O₄@PDA NPs was achieved by utilizing PDA as both the reducing agent and the coupling agent. The satellite nanocatalysts exhibited high catalytic performance for the reduction of p-nitrophenol. Furthermore, the recovery and reuse of the catalyst was demonstrated 8 times without detectible loss in activity. The synergistic combination of unique features of PDA and magnetic nanoparticles establishes these core–shell NPs as a versatile platform for potential applications.     

Synthesis of nano‐sized magnetite mesoporous carbon for removal of Reactive Yellow dye from aqueous solutions

In this study, core‐shell structures of magnetite nanoparticles coated with CMK‐8 ordered mesoporous carbon (Fe₃O₄@SiO₂‐CMK‐8 NPs) have been successfully synthesized for the first time by carbonizing sucrose inside the pores of the Kit‐6 mesoporous silica. The nano‐sized mesoporous particles were characterized by X‐ray diffraction, Fourier transform‐infrared spectroscopy, scanning electron microscope, dynamic light scattering, vibrating‐sample magnetometer, Brunauer–Emmett–Teller (BET) and transmission electron microscopy instruments. The obtained nanocomposite was used for removal of Reactive Yellow 160 (RY 160) dye from aqueous samples. The N₂ adsorption–desorption method (at 77 K) confirmed the mesoporous structure of synthesized Fe₃O₄@SiO₂‐CMK‐8 NPs. Also, the surface area was calculated by the BET method and Langmuir plot as 276.84 m²/g and 352.32 m²/g, respectively. The surface area, volume and pore diameter of synthesized nanoparticles (NPs) were calculated from the pore size distribution curves using the Barrett–Joyner–Halenda formula (BJH). To obtain the optimum experimental variables, the effect of various experimental parameters on the dye removal efficiency was studied using Taguchi orthogonal array experimental design method. According to the experimental results, about 90.0% of RY 160 was removed from aqueous solutions at the adsorbent amount of 0.06 g, pH 3 and ionic strength = 0.05 m during 10 min. The pseudo‐second order kinetic model provided a very good fit for the RY 160 dye removal (R² = 0.999). The Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models were applied to describe the equilibrium isotherms, and the Langmuir isotherm showed the best fit to data with the maximum adsorption capacity of 62.893 mg/g. Furthermore, the Fe₃O₄@SiO₂‐CMK‐8 NPs could be simply recovered by external magnet, and exhibited recyclability and reusability for a subsequent six runs.     

Simple Surfactant Concentration‐Dependent Shape Control of Polyhedral Fe3O4 Nanoparticles and Their Magnetic Properties

The shape and size of monodisperse Fe₃O₄ nanoparticles (NPs) are controlled using a chemical solution synthesis in the presence of the surfactant cetylpyridinium chloride (CPC). Cubic Fe₃O₄ NPs surrounded by six {100} planes are obtained in the absence of CPC. Increasing the CPC content during synthesis causes the shape of the resulting Fe₃O₄ NPs to change from cubic to truncated cubic, cuboctahedral, truncated octahedral, and finally octahedral. During this evolution, the predominantly exposed planes of the Fe₃O₄ NPs vary from {100} to {111}. The shape control results from the synergistic effect of the pyridinium cations, chloride anions, and long‐chain alkyl groups of CPC, which is confirmed by comparison with NPs synthesized in the presence of various related cationic surfactants. The size of the cubic Fe₃O₄ NPs can be tuned from 50 to 200 nm, by changing the concentration of oleic acid in the reaction solution. The Fe₃O₄ NPs exhibit shape‐dependent saturation magnetization, remanent magnetization, and coercivity.     

Promising photoluminescence optical approach for triiodothyronine hormone determination based on smart copper metal–organic framework nanoparticles

A copper metal–organic framework nanoparticles (Cu‐MOF‐NPs) synthesized via simple technique. The prepared Cu‐MOF‐NPs nanoparticles were further characterized using ¹H‐NMR, FE‐SEM/EDX and thermal study (DSC/TGA). The FE‐SEM/EDX, thermal analysis, and NMR spectrum data with the other analysis support the nano‐Cu‐MOF structure and the monomeric unit (n[Cu (AIP)₂(APY)(H₂O)₂].4H₂O) of Cu‐MOF‐NPs. The photoluminescence (PL) studies of triiodothyronine hormone (T3) based on the prepared Cu‐MOF‐NPs investigated. The results revealed that the Cu‐MOF‐NPs might be used as a biosensor in the determination of triiodothyronine hormone (T3) in biological fluids through a significant quenching of the photoluminescence intensity of Cu‐MOF‐NPs at excitation wavelength 492 nm. The calibration plot achieved over the concentration range 0.0–200.0 ng/dL T3 hormone with a correlation coefficient 0.996 and limit of detection (LOD) and quantification (LOQ) 0.198 and 0.60 ng/dL, respectively. The PL spectra are indicating that Cu‐MOF‐NPs has highly selective sensing properties for T3 hormone without interfering with other human many hormones types. This approach considered a promising analytical tool for early diagnosis of the cases of thyroid disease. The mechanism of quenching between the Cu‐MOF‐NPs, and T3 hormone studied. The mechanism was a dynamic type and obtained due to the energy transfer mechanism.