Jerina Majeed

Inorganic–organic multiferroic hybrid films of Fe3O4 and PVDF with significant magneto-dielectric coupling

Flexible and self-standing inorganic-organic hybrid films of silica coated Fe3O4 nanoparticles and polyvinylidene fluoride (PVDF) polymer with significant magneto-dielectric coupling have been prepared at low temperature by a simple solvent casting method. PVDF films with two different concentrations of silica coated Fe3O4 (4.76 and 9.09 wt%) have been developed and well characterized using different techniques like XRD, TEM and IR. The thin film coating of silica on Fe3O4 could be detected by IR and TEM. The ferroelectric, magnetic and magneto-capacitive measurements at room temperature confirm the multiferroic nature of the composite films with significant magneto-electric coupling between Fe3O4 and PVDF.

Enhanced specific absorption rate in silanol functionalized Fe3O4 core–shell nanoparticles: Study of Fe leaching in Fe3O4 and hyperthermia in L929 and HeLa cells

Core-shell Fe3O4-SiO2 magnetic nanoparticles (MNPs) have been synthesized using a simple synthesis procedure at different temperatures. These MNPs are used to investigate the effect of surface coating on specific absorption rate (SAR) under alternating magnetic field. The temperature achieved by silica coated Fe3O4 is higher than that by uncoated MNPs (Fe3O4). This can be attributed to extent of increase in Brownian motion for silica coated MNPs. The sample prepared at optimized temperature of 80°C shows the highest SAR value of 111W/g. It is found that SAR value decreases with increase in shell thickness. The chemical stability of these samples is analyzed by leaching experiments at pH 2-7. The silica coated samples are stable up to 7 days even at pH 2. Biocompatibility of the MNPs is evaluated in vitro by assessing their cytotoxicity on L929 and human cervical cancer cells (HeLa cells) using sulforhodamine-B assay. Their hyperthermic killing ability is also evaluated in HeLa cells using the same method. Cells treated with MNPs along with induction heating show decrease in viability as compared to that without induction heating. Further, cell death is found to be ∼55% more in cells treated with silica coated MNPs under induction heating as compared to untreated control. These results establish the efficacy of Fe3O4-SiO2 prepared at 80°C in killing of tumor cells by cellular hyperthermia.

Water-dispersible polyphosphate-grafted Fe3O4 nanomagnets for cancer therapy

We report the development of a new class of water-dispersible polyphosphate-grafted Fe3O4 nanomagnets (PPNMs) by a facile soft chemical approach. The grafting of polyphosphate with Fe3O4 nanoparticles is evident from Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), dynamic light scattering (DLS) and zeta-potential measurements. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses reveal the formation of highly crystalline Fe3O4 nanoparticles with an average size of about 10 nm. These nanoparticles show good colloidal stability, strong magnetic field responsivity and protein resistance characteristics. Induction heating studies confirm localized heating of these superparamagnetic PPNMs with good intrinsic loss power under an AC magnetic field (AMF). The drug loading and release behavior of the PPNMs was explored using doxorubicin hydrochloride (DOX) as a model drug. The decrease in fluorescence intensity and increase in surface charge of drug-loaded PPNMs strongly suggest the conjugation of DOX with the PPNMs. The cell viability and hemolysis assays suggest that the PPNMs do not have adverse toxic effects for further in vivo use. Specifically, high loading affinity for DOX with sustained release, substantial cellular internalization and self-heating capacity makes these novel magnetic nanoparticles suitable for drug delivery and hyperthermia therapy applications.

Kinetic modeling: dependence of structural and sorption properties of ZnO—crucial role of synthesis

Zinc oxide nanoparticles were synthesized by two different routes namely pyrolytic and gel combustion methods and characterized using different techniques like XRD, TGA/DSC, diffuse reflectance spectrophotometry, zeta potential, NMR and IR. The efficiency of the nanoparticles with respect to sorption of different toxic species like chromate and rhodamine 6G was evaluated. The studies showed that the synthesis route adopted affects the characteristics of the nanoparticles, thus leading to the difference in sorption efficiency. The mechanism of sorption proposed was based on the different characterization studies and it was found that the sorption was not only an electrostatic interaction but can occur due to the presence of pores or some binding groups. The highly pH-dependent sorption efficiency of the nanoparticles is evident from the results, whereas their kinetics was described by a pseudo-second-order kinetic model and further explained by using Weber–Morris and Boyd models. The overall rate process appeared to be influenced by both external mass transfer and intraparticle diffusion. Considering the simplicity of the synthetic procedure and the possibility of a cost effective catalyst, the developed nanomaterials have great potential for applications in water treatment technologies.

Correlation of Mo dopant and photocatalytic properties of Mo incorporated TiO2: an EXAFS and photocatalytic study

The present study addresses the quantitative estimation and understanding of the nature of phases present in Mo-incorporated titania through extensive EXAFS measurements (at Mo K-edge and Ti K-edge) and to decipher their role in photodegradation of Methylene Blue (MB) dye under UV and visible irradiation. EXAFS results revealed the presence of both MoO3 nano heterophase phase and substitutional Mo dopants in the TiO2 lattice, the extent of the latter was reduced with the increasing Mo content of the sample. The presence of MoO3 in the Mo-incorporated titania was also revealed by FT-IR and TEM studies. Photocatalytic studies have shown considerable adsorption of the cationic MB-dye, perhaps due to the electronic interaction between the dye and catalytic surface. Under visible irradiation, the photocatalytic activity followed the trend: Mo-5 > Mo-2 > Mo-1 > Mo-10 ≫ TiO2, while the trend for photodegradation of MB dye under UV irradiation was as follows: Mo-5 > Mo-2 > Mo-1 > TiO2 > Mo-10. These results have been explained in the light of the structural properties of the Mo–TiO2 system obtained from EXAFS measurements. It has been observed that the relative ratio of substitutional Mo-dopant to the MoO3 phase in this tri-phasic photocatalyst plays a crucial role in augmenting its oxidative photocatalytic property.

Multifunctional hybrid structures of ferromagnetic FePt and ferroelectric BaTiO3 nanoparticles: facile synthesis and characterization

Nanohybrid structures of FePt and BaTiO3 with bifunctional properties were synthesized by a two step synthesis procedure including solid state and solvothermal methods. Two different compositions of FePt and BaTiO3 nanoparticle samples were synthesized. The hybrid composite, having the lower FePt concentration, exhibited bifunctionality including superparamagnetism with a blocking temperature near room temperature and ferroelectricity at ambient conditions. Magnetocapacitive measurements of this bifunctional FePt–BiTiO3 sample showed behaviour typical of weak magnetoelectric coupling. This synthetic approach provides a general method for preparing advanced multifunctional and technologically important ceramic–alloy hybrids.

Effect of Synthesis Protocol on the Surface Charge of Zinc Oxide Nanoparticles and its Consequence on Sorption Ability

The surface charge of nanosorbents is a very important factor which affects applications. In the present paper, the surface charge of ZnO NPs was tailored using by adopting different synthesis protocols. The synthesized nanoparticles were characterized and zeta potential measurements showed that the ZnO Nps synthesized by pyrolysis method (ZnO (PY)) and the gel-combustion method (ZnO (GC)) possess a positive charge while the co-precipitation method results in nanoparticles (ZnO (CP)) with negative surface charge.

Fe3O4@SiO2 core-shell nanoparticles: Synthesis, characterization and application in environmental remediation

In this study, Fe3O4@SiO2 core-shell structure was synthesized by a one pot co-precipitation method, and its applicability as Low-Cost Abundantly available adsorbent for removal of heavy metal ions from simulated industrial waste water was examined. The detailed characterization of morphology showed that the Fe3O4 nanoparticle was coated with amorphous silica of a shell thickness of 2–3 nm. The core-shell magnetic nanoparticles (MNPs) showed a great removal capability of four different heavy metal ions (Zn (II), Co (II), Ni (II), and Cu (II). These MNPs showed high magnetic saturation values, which ensure the convenience of recovering sorbent for reusability with the assistance of external magnetic field. Specifically, this present study shows the use of MNPs as an effective recyclable adsorbent for environmental remediation.