Ravi Kumar

In this work, we design a magneto-luminescent nanocomposite system comprised of magnetic ferrite nanoparticles and a Ln³⁺-based luminophore, with an excellent balance of lanthanide emission and induction heating capacity, which remains a challenge. At first, we encapsulate Zn-doped ferrite nanoparticles (Zn_xFe_3-xO₄; x ≈ 0.3) of size ∼20 nm within thin layers of silica and amorphous Gd₂O₃ doped with Eu³⁺ (5 atom %), respectively. Then, we activate the Eu³⁺ luminescence in Zn_xFe_3-xO₄@SiO₂@Gd₂O₃:Eu³⁺ (Eu-ZFO) nanocomposites using the organic ligand 2-thenoyltrifluoroacetone (TTA)-mediated surface passivation approach. We find that the resulting nanocomposites (Eu-ZFO-TTA NCs) display bright red Eu³⁺-emission (quantum yield 9.3%) under near-UV excitation with a long emission lifetime (0.181 ms) and high stability against photoluminescence leakage. Moreover, we witness a significant magnetization (39.3 emu/g) and, thereby, a remarkably high induction heating capacity of Eu-ZFO-TTA NCs than the reported magneto-luminescent nanocomposites. This is depicted by the intrinsic loss power of Eu-ZFO-TTA NCs as high as 11 nH m²/kg in an aqueous dispersion under an AC magnetic field (AMF) of 12 kA/m, 335 kHz. Finally, we examine the bioimaging and AMF-induced hyperthermia performance of the nanocomposites in vitro on human lung adenocarcinoma A549 cells using a live cell confocal fluorescence microscopy study and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. We find the Eu-ZFO-TTA NCs highly biocompatible (IC₅₀ = approximately 800 μg/mL), and their intense red emission is very effective for monitoring their cellular internalization. Moreover, only 200 μg/mL dose of NCs is sufficient to induce significant cell death (>75%) under AMF. Besides, we perform a hemolysis test and observe that our NCs exhibit a high hemocompatibility at the 200 μg/mL dose (<5% hemolysis). These outcomes imply an immense prospect for Eu-ZFO-TTA NCs to replace the reported magneto-luminescent nanomaterials for future in vivo optical image-guided low-field magnetic hyperthermia therapy of cancer.

The objective of the present investigation is to optimize the thickness of Pulse Laser Deposition (PLD)-grown CoFe thin films to achieve minimal effective Gilbert damping (αeff) for potential spintronics applications. The effect of the thickness (5-30 nm) of CoFe ultra-thin films on the Si/SiO2 substrate on the structural, morphological and magnetic properties has been reported. The X-ray diffraction (XRD) peak at 44.5° shows the growth of CoFe along the (110) crystal plane. A nearly square M-H loop with high saturation magnetization (Ms) suggests good crystalline growth of CoFe film. A high coercive field (Hc) observed in the thinnest 5 nm film is due to defects such as dislocations and stacking faults that appear at very low thickness. These defects gradually decrease with an increase in CoFe film thickness, as evident from a decrease in the Hc and an increase in the Ms. The value of αeff is largest for the thinnest 5 nm film due to defects and magnetic inhomogeneities present at this thickness. The damping is reduced by approximately one-third for the 10 nm thin film in comparison to the 5 nm film, which signifies a good quality film with fewer disorders.

Magnetic nanoparticle (MNP)-mediated magnetic hyperthermia (MHT) under an alternating magnetic field (AMF) causes tumor regression via reactive oxygen species (ROS) generation. However, less therapeutic efficacy has been reported due to the generation of low levels of ROS in a hypoxic tumor microenvironment. Therefore, improved treatments are required to generate relatively high levels of ROS to promote irreversible oxidative damage to the tumor cells. Herein, we report a magnetothermodynamic (MTD) therapy, as a robust and versatile approach for cancer treatment, by combining the magnetothermodynamic-related ROS and heat-related immunological effect in order to overcome the aforementioned obstacle. The synergistic therapy was achieved by the development of vitamin k3 (Vk3)-loaded copper zinc ferrite nanoparticles (Vk3@Si@CuZnIONPs) as an efficient MTD agent. The in vitro results unveiled that enhanced ROS production under the influence of AMF is a predominant aspect in yielding an assertive anticancer response. The in vivo antitumor response was assessed in an ectopic tumor model of A549 lung adenocarcinoma by MTD. The tumor inhibition rate of 69% was achieved within 20 days of MTD treatment, exhibiting complete tumor eradication within 30 days. The validation of antitumor response was marked by severe apoptosis (TUNEL, Caspase-3) in the Vk3@Si@CuZnIONPs + AMF-treated group. The higher expression level of heat shock proteins and proinflammatory cytokines (IL-6, TNF-α, IL-1α, IL-1β) was speculated to play a role in the activation of immune response for faster tumor regression in the MTD-treated group. Therefore, by implementing a dual ROS and heat-mediated immunogenic effect, the antitumor efficiency of future cancer magnetotherapies will be greatly enhanced.

Spintronics, also known as magneto-electronics or spin transport electronics, uses the magnetic moment of the electron due to intrinsic spin along with its electric charge. In the present review, the topological insulators (2D, 3D, and hydride) were discussed including the conducting edge of 2D topological insulators (TIs). Preparation methods of TIs along with fundamental properties, such as low power dissipation and spin polarized electrons, have been explored. Magnetic TIs have been extensively discussed and explained. Weyl phases, topological superconductors, and TIs are covered in this review. We have focused on creating novel spintronic gadgets based on TIs which have metallic topological exterior facades that are topologically defended and have an insulating bulk. In this review, topological phases are discussed as a potential candidate for novel quantum phenomena and new technological advances for fault-tolerant quantum computation in spintronics, low-power electronics, and as a host for Majorana fermions are elucidated. Room temperature stable magnetic skyrmions and anti-skyrmions in spintronics for next-generation memory/storage devices have been reported.

Chitosan-coated Fe₃O₄nanoparticles induced rapid tumor ablation using magnetic hyperthermia, possibly mediated by caspase-3 dependent apoptosis andIL-6signaling, and showed gradual clearance from the excretory, hepatic and circulatory system in rats.

In this work, we have designed a magneto-luminescent nanocomposite as a single platform for optical imaging and safe magnetic hyperthermia therapy by optimizing the composition of magnetic nanoparticles and controlling the conjugation strategy of the luminescent lanthanide complex. We have synthesized Co_xMn_1-xFe₂O₄ nanoferrites, with x = 0 to 1 in 0.25 steps, from soft (MnFe₂O₄) to hard (CoFe₂O₄) ferrites of size (~20 nm) following a one-pot oxidative hydrolysis method. We have performed the induction heating study with an aqueous dispersion of nanoferrites using an alternating magnetic field (AMF) of 12 kAm^-1, 335 kHz. This shows an enhancement of heating efficiency with the increment of manganese content and attains the highest intrinsic loss power (ILP) of 6.47 nHm²kg^-1 for MnFe₂O₄ nanoparticles. We have then fabricated magneto-luminescent nanocomposite employing MnFe₂O₄ nanoparticles as it shows outstanding heating performance within the threshold limit of AMF (≤ 5×10⁹ Am^-1s^-1). A layer-by-layer coating strategy is followed where a pure silica coating of thickness ~10 nm on MnFe₂O₄ nanoparticles is achieved before encapsulation of the luminescent complex of europium(III), 2-thenoyltrifluoroacetone and 1,10-phenanthroline in the second layer of silica. This is to ensure the optimal distance between magnetic core and Eu(III)-complex to pertain significant luminescence in the composite (Eu-MnFe₂O₄). The photoluminescence spectra of an aqueous dispersion of Eu-MnFe₂O₄ by excitation in the UV region shows a narrow and strong emission at 612 nm which is stable even after 72 h. The induction heating study of an aqueous dispersion of Eu-MnFe₂O₄ in 12 kAm^-1, 335 kHz AMF shows an ILP as 4.02 nHm²kg^-1 which is remarkably higher than the hyperthermia efficiency of reported magneto-luminescent nanoparticles.

Graphene based 2D materials with a surfeit of active sites and advantageously high surface to volume ratio are effectively linked to well established nanostructured semiconducting metal oxides for development of nanocomposites with enhanced gas sensing properties. Graphene Oxide (GO), a sister material of graphene, is therefore a natural choice for development of room temperature operated gas sensors. In the current investigation hydrothermally grown GO and ZnO nanorods composite (GO–ZnO–NR) is utilised for room temperature gas sensing of H₂ and SO₂ gases. Room temperature detection of H₂ and SO₂ at sub-100 ppm levels with linear variation in response for different concentrations is demonstrated. Morphological and structural analyses are conducted using Scanning electron microscopy, Raman spectroscopy and X-ray diffraction. GO-ZnO-NR composite sensor is seen to exhibit robust sensing response of 5.82 and 5.45 for 100 ppm each of H₂ and SO₂ gases respectively at room temperature. Further, the delayed response and recovery times exhibited by the sensor for SO₂ gas are recognized to be due to formation of strongly adhering SO₃ species.

Aim: To explore the optimum temperature for cancer cell death using magnetic hyperthermia (MH), which in turn will affect the mode of cell death. Method: The focus of this study is to improve upon ...