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Unlike any other nanoparticles known to date, magnetoelectric nanoparticles (MENPs) can generate relatively strong electric fields locally via the application of magnetic fields and, vice versa, have their magnetization change in response to an electric field from the microenvironment. Hence, MENPs can serve as a wireless two-way interface between man-made devices and physiological systems at the molecular level. With the recent development of room-temperature biocompatible MENPs, a number of novel potential medical applications have emerged. These applications include wireless brain stimulation and mapping/recording of neural activity in real-time, targeted delivery across the blood-brain barrier (BBB), tissue regeneration, high-specificity cancer cures, molecular-level rapid diagnostics, and others. Several independent in vivo studies, using mice and nonhuman primates models, demonstrated the capability to deliver MENPs in the brain across the BBB via intravenous injection or, alternatively, bypassing the BBB via intranasal inhalation of the nanoparticles. Wireless deep brain stimulation with MENPs was demonstrated both in vitro and in vivo in different rodents models by several independent groups. High-specificity cancer treatment methods as well as tissue regeneration approaches with MENPs were proposed and demonstrated in in vitro models. A number of in vitro and in vivo studies were dedicated to understand the underlying mechanisms of MENPs-based high-specificity targeted drug delivery via application of d.c. and a.c. magnetic fields. This article is categorized under: Nanotechnology Approaches to BiologyNanoscale Systems in Biology Therapeutic Approaches and Drug DiscoveryNanomedicine for Neurological Disease Therapeutic Approaches and Drug DiscoveryNanomedicine for Oncologic Disease Therapeutic Approaches and Drug DiscoveryEmerging Technologies.

Electroporation has been shown to be an effective method of intracellular drug delivery and tissue ablation, however it faces significant challenges not only in clinical application due to the risks associated with the necessity of high voltage electrodes, but also due to a lack of fundamental research into the electrical characteristics of cancer cells. In order to improve outcomes in the clinic when using irreversible electroporation(IRE), it will be crucial to create a deeper understanding of the mechanisms underlying electroporation, such as the impacts of resting membrane potential on IRE outcomes. Magnetoelectric-nanoparticles (MENPs)have proven their ability to generate electric fields when stimulated by an external magnetic field and thus may be an effective alternative to electrodes for in-vivo electroporation and electro-chemotherapy. The ability of MENPs to electroporate cells is limited by the strength of their magnetoelectric (ME)effect, as such it is important to optimize MENPs fabrication for future applications. Improving this technology will require a deeper understanding of the membrane potential and other electrical properties of cancer cells.We fabricated MENPs consisting of a magnetostrictive CoFe2O4 core coupled with a piezoelectric BaTiO3shell. SKOV-3 and HOMEC cells were seeded in culture plates and given a 50ul dose of particle suspension, and 10ul of propidium iodide(PI). The cell samples were then stimulated by a 10 minute exposure to an alternating magnetic field of 400Oe at 100Hz. Fluorescence-microscope images were taken at 5 minute intervals during, and for 10 minutes following, the magnetic stimulation. These images were processed in MATLAB to quantify total fluorescence, and thus PI uptake, over time for each cell culture-particle combination.MENPs coupled with magnetic field stimulation were able to cause PI uptake in both HOMEC and SKOV-3 cells, indicating electroporation had occurred. By adding PI at time intervals after stimulation, we were able to determine whether electroporation had been reversible or irreversible by showing dye uptake would stop soon after stimulation had ended in the case of reversible EP but not IRE. We found SKOV-3 to have been reversibly electroporated, and HOMEC to have undergone IRE. To understand these results we used Oxonol uptake in a flow cytometry measurement to estimate resting membrane potential (RMP). HOMEC cells were shown to have a RMP approximately 20mV smaller than SKOV-3, which corresponded to the occurrence of IRE in HOMEC compared to reversible electroporation in SKOV-3.These results demonstrate the efficacy of MENPs to electroporate mammalian cells in the presence of a magnetic field. They also indicate a link between RMP and reversibility of electroporation. Further research into the electrical properties of cancer cells will be needed to formulate a complete model of the interactions between the nanoparticles and mammalian cells. Citation Format: Max Shotbolt, Victoria Andre, Skye Conlan, Ping Liang, Sakhrat Khizroev. Investigating the impacts of membrane potential on nano-electroporation efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 819.

Magnetoelectric coefficient values of above 5 and 2 V cm-1 Oe-1 in 20 nm CoFe2O4-BaTiO3 and NiFe2O4-BaTiO3 core-shell magnetoelectric nanoparticles were demonstrated. These colossal values, compared to 0.1 V cm-1 Oe-1 commonly reported for the 0-3 system, are attributed to (i) the heterostructural lattice-matched interface between the magnetostrictive core and the piezoelectric shell, confirmed through transmission electron microscopy, and (ii) in situ scanning tunneling microscopy nanoprobe-based ME characterization. The nanoprobe technique allows measurements of the ME effect at a single-nanoparticle level which avoids the charge leakage problem of traditional powder form measurements. The difference in the frequency dependence of the ME value between the two material systems is owed to the Ni-ferrite cores becoming superparamagnetic in the near-dc frequency range. The availability of novel nanostructures with colossal ME values promises to unlock many new applications ranging from energy-efficient information processing to nanomedicine and brain-machine interfaces.

Nanomedicine, an emerging field at the intersection of medicine and nanotechnology, has the potential to be revolutionary. The human body is an extremely complex engineering system optimized through many years of evolution. It involves trillions of interconnected cells; intrinsic electric fields at the subcellular level play an important role in these interactions and, ultimately, define fundamental physiological mechanisms.

Almost 1000 million people have recently been diagnosed with a mental health or substance disorder (RitchieRoser, 2018). Psychiatric disorders, and their treatment, represent a big burden to the society worldwide, causing about 8 million deaths per year (Walker et al., 2015). Daily progress in science enables continuous advances in methods to treat patients; however, the brain remains to be the most unknown and complex organ of the body. There is a growing demand for innovative approaches to treat psychiatric as well as neurodegenerative disorders, disorders with unknown curability, and treatments mostly designed to slow disease progression. Based on that need and the peculiarity of the central nervous system, in the present review, we highlight the handicaps of the existing approaches as well as discuss the potential of the recently introduced magnetoelectric nanoparticles (MENPs) to become a game-changing tool in future applications for the treatment of brain alterations. Unlike other stimulation approaches, MENPs have the potential to enable a wirelessly controlled stimulation at a single-neuron level without requiring genetic modification of the neural tissue and no toxicity has yet been reported. Their potential as a new tool for targeting the brain is discussed. This article is categorized under: Therapeutic Approaches and Drug DiscoveryNanomedicine for Cardiovascular Disease Therapeutic Approaches and Drug DiscoveryNeurological Disease.

Wireless and precise stimulation of deep brain structures could have important applications to study intact brain circuits and treat neurological disorders. Herein, we report that magnetoelectric nanoparticles (MENs) can be guided to a targeted brain region to stimulate brain activity with a magnetic field. We demonstrated the nanoparticles’ capability to reliably evoke fast neuronal responses in cortical slices ex vivo. After fluorescently labeled MENs were intravenously injected and delivered to a targeted brain region by applying a magnetic field gradient, a magnetic field of low intensity (350–450 Oe) applied to the mouse head reliably evoked cortical activities, as revealed by two-photon and mesoscopic imaging of calcium signals and by an increased number of c-Fos expressing cells after stimulation. Neither brain delivery of MENs nor the magnetic stimulation caused significant increases in astrocytes and microglia. Thus, MENs could enable a non-invasive and contactless deep brain stimulation without the need of genetic manipulation. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13311-021-01071-0.

We report a one-step synthesis of nicotine-containing nanoparticles by using a size-controllable nanofiltration technique. Nanostructures with polydimethylsiloxane (PDMS) were prepared as a biocompatible well-type polymeric carrier containing a hydrophobic and highly viscous nicotine drug through a novel spontaneous emulsification solvent diffusion method. This approach could be used for efficient dispersion of nicotine in biological systems. Our present results, together with size controllability, pave a way to new types of functional material structures for novel transdermal pharmaceuticals that contain nicotine/cotinine in nanosized structures.

Understanding the physics of spintronic devices in the 3-nm size range can pave the way to next-generation energy-efficient information processing devices. To build a spin computer, a layer of 3-nm CoFe 2 O 4 nanoparticles was sandwiched as a central layer into the standard spin-transfer torque magnetic tunneling junction (STT-MTJ) stack. With further focused ion beam (FIB) trimming, a dual-layer junction consisting of one or more nanoparticles separating two CoFeB ferromagnetic layers was turned into a two-terminal spintronic device. The measured room-temperature electron transport through the device showed a staircase effect reminiscent of a single electron transport, which in addition depended on the relative orientations of the magnetic states of the ferromagnetic layers and the high-anisotropy ferrimagnetic nanoparticle. Besides having the staircase steps, the V-I curve indicated switching of the nanoparticles magnetization through the STT effect at currents of above 0.05 uA. The magnetoresistance (MR) curve of this device with the magnetic field applied perpendicular to the junction had an anomalous oscillatory field dependence in a relatively low field range of below 100 Oe.

Nanotechnology is a novel tool for handling of matter at the microscopic level, within the atomic, molecular, and supramolecular domains. While neuroscience and neuroengineering operate at the cellular level, their association with the nanotechnology is bringing synergic unexpected strides. In the last decade, an unprecedented increase in the successful application of nanotechnology methods to basic neuroscience and to clinical practice occurred. Novel nanotechnologies are expected to bring important insights into brain mechanisms and medical care to patients. The chapter details attempt from different disciplines to improve brain performance in both healthy people and patients who suffer from neurological disabilities. Applications of nanotechnology (with the advent of nanoparticles, nanowires, carbon nanotubes, devices, sensors, interfaces) are employed to augment, invasive/noninvasive record, stimulate, repair, cure, or regenerate the brain functions (sensory, motor/locomotor, cognitive/memory/learning, reward/emotion) and brain circuitry (in cortex, subcortex/basal ganglia/thalamus, brainstem, spinal cord).

This paper presents an experimental study in which 30-nm CoFe2O4–BaTiO3 core-shell magnetoelectric nanostructures (MENs) were embedded into graphite sheets to enable external control of intrinsic properties such as the intercalation process. The embedded nanoparticles were self-assembled into a honeycomb pattern with a characteristic period on the order of 200 nm, as confirmed through energy-dispersive spectroscopy (EDS) by scanning electron microscopy (SEM) as well as through atomic and magnetic force microscopy (AFM and MFM). Integration of the nanoparticles into the graphite structure was also confirmed through Fourier transform infrared (FT-IR) imaging and X-Ray diffraction (XRD) analysis. XRD measurements indicate crystallographic changes in the response to application of a 500-Oe magnetic field. M-H measurements by vibrating sample magnetometer (VSM) showed the coercivity of the nanoparticles on the order of 250 Oe.

Aim: We studied externally controlled anticancer effects of binding tumor growth inhibiting synthetic peptides to magnetoelectric nanoparticles (MENs) on treatment of glioblastomas. Methods: Hydrothermally synthesized 30-nm MENs had the core–shell composition of CoFe2O4@BaTiO3. Molecules of growth hormone-releasing hormone antagonist of the MIA class (MIA690) were chemically bound to MENs. In vitro experiments utilized human glioblastoma cells (U-87MG) and human brain microvascular endothelial cells. Results: The studies demonstrated externally controlled high-efficacy binding of MIA690 to MENs, targeted specificity to glioblastoma cells and on-demand release of the peptide by application of d.c. and a.c. magnetic fields, respectively. Conclusion: The results support the use of MENs as an effective drug delivery carrier for growth hormone-releasing hormone antagonists in the treatment of human glioblastomas.

New types of functional material structures will emerge if the shape and properties are controlled in three-dimensional nanodevices. Possible applications of these would be nanoelectronics and medical systems. Magnetic nanoparticles (MNPs) are especially important in electronics such as magnetic storage, sensors, and spintronics. Also, in those that are used as magnetic resonance imaging contrasts, and tissue specific therapeutic agents, as well as in the labeling and sorting of cells, drug delivery, separation of biochemical products, and in other medical applications. Most of these applications require MNPs to be chemically stable, uniform in size, and controllable in terms of their magnetic properties and shape. In this paper three new functions of iron (Fe)-based nanoparticles are reported: shape transformation, oxidation prevention, and self-alignment. The shape of the Fe nanoparticles could be controlled by changing their oxidation states and properties by using a nanocarbon coating. Full field X-ray microscopy using synchrotron radiation revealed controllable magnetic properties of MNPs at the L3 edge which depended on the oxidation states. Then, inkjet printing was successfully performed to deposit a uniform layer of MNPs by the size.

The brain is a massive network of neurons which are interconnected through chemical and electrical field oscillations. It is hard to overestimate the significance of the ability to control chemical and physical properties of the network at both the collective and single-cell levels. Most psychiatric and neurodegenerative diseases are typically characterized by certain aberrations of these oscillations. Recently, magnetoelectric nanoparticles (MENs) have been introduced to achieve the desired control. MENs effectively enable wirelessly controlled nanoelectrodes deep in the brain. Although MENs have been shown to cross the blood-brain barrier via intravenous (IV) administration, achieving adequate efficacy of the delivery remains an open question. Herein, through in vivo studies on a mouse model, we demonstrate at least a 4-fold improved efficacy of the targeted delivery of MENs across BBB via intranasal administration compared to an equivalent IV administration.

Cobalt ferrite – barium titanate coreshell composite nanoparticles are an important part of the emerging field of magnetoelectric materials. Understanding the structure of these nanoparticles is vital towards controlling and adjusting their key properties for specific applications. Although transmission electron microscopy can reveal nanoparticle size, shape, and crystallinity, key information regarding the magnetic properties and the compositional makeup of the coreshell configuration remains elusive at nanoscale. This paper covers the use of scanning probe microscopy to directly measure these features using topography imaging, magnetic force imaging, and phase imaging. This technique provides significant insights into the intrinsic magnetoelectric coupling between the magnetostrictive cobalt ferrite core and the piezoelectric barium titanate shell. Particularly, this technique was applied to obtain phase images that directly exhibited the coreshell configuration, including an intermediate transition region between the core and the shell. The samples examined include 20 nm and 50 nm cobalt ferrite-barium titanate coreshell nanoparticles fabricated via co-precipitation and sol–gel synthesis. The results revealed a cuboid shape for the cobalt ferrite cores, and an oval shape for the cobalt ferrite-barium titanate coreshell nanoparticles. This result was confirmed by transmission electron microscopy. Additionally, the paper comprehensively analyzes the samples in their powder form via X-ray diffraction. The results indicate that the crystallinity of barium titanate is enhanced as the cobalt ferrite concentration is increased because of heterogeneous nucleation requiring a lower nucleation barrier compared to homogeneous nucleation.

The spin-transfer torque magnetic tunneling junction (MTJ) technology may pave a way to a universal memory paradigm. MTJ devices with perpendicular magnetic anisotropy have the potential to have high thermal stability, high tunneling magnetoresistance, and low critical current for energy-efficient current-induced magnetization switching. Using devices fabricated through focused ion beam etching with Ga- and Ne-ion beams, this paper aimed to understand the size dependence of the current/voltage characteristics in the sub-10 nm range. The switching current density drastically dropped around 1 MA/cm $^{\mathrm { {2}}}$ as the device size was reduced below 10 nm. A stability of over 22 kT measured for a 5 nm device indicated a significantly reduced spin relaxation time.

Spin-transfer torque (STT) magnetic tunnel junctions (MTJs) in the sub-10-nm size range have shown enhancement in energy efficiency. This improved switching energy efficiency means a longer spin relaxation time, a corresponding stronger spin accumulation, and a resulting lower switching current density. This improvement in switching energy efficiency stems from a reduction in damping as the device size is reduced. This can be seen by a reduction in the damping constant in the Landau-Lifshitz Gilbert (LLG) equation. This term can take a range of values, and this range depends on the different contributions from the surface relative to the bulk. Specifically, at such small sizes the damping constant differs from the bulk damping constant. In this study, a detailed equation defining this surface-to-volume relative contribution was developed. This theory was tested through simulations involving a sub-10-nm cobalt cube utilizing the Object Oriented Micromagnetic Framework (OOMMF). These simulations showed a longer spin relaxation time with a decrease in device size (defined by side length) as well as a reduction in switching current density with a decrease in side length. This reduction in switching current density was approximately logarithmic versus volume, surface area, and side length. Moreover, in the sub-5-nm range, this reduction was nearly linear with respect to side length. These results agree with theoretical predictions and they are aligned with the experimentally demonstrated quantum size effect.

Background Neurodegenerative diseases are devastating diagnoses. Examining local electric fields in response to neural activity in real time could shed light on understanding the origins of these diseases. To date, there has not been found a way to directly map these fields without interfering with the electric circuitry of the brain. This theoretical study is focused on a nanotechnology concept to overcome the challenge of brain electric field mapping in real time. The paper shows that coupling the magnetoelectric effect of multiferroic nanoparticles, known as magnetoelectric nanoparticles (MENs), with the ultra-fast and high-sensitivity imaging capability of the recently emerged magnetic particle imaging (MPI) can enable wirelessly conducted electric-field mapping with specifications to meet the requirements for monitoring neural activity in real time. Methods The MPI signal is numerically simulated on a realistic human brain template obtained from BrainWeb, while brain segmentation was performed with BrainSuite software. The finite element mesh is generated with Computer Geometry Algorithm Library. The effect of MENs is modeled through local point magnetization changes according to the magnetoelectric effect. Results It is shown that, unlike traditional magnetic nanoparticles, MENs, when coupled with MPI, provide information containing electric field’s spatial and temporal patterns due to local neural activity with signal sensitivities adequate for detection of minute changes at the sub-cellular level corresponding to early stage disease processes. Conclusions Like no other nanoparticles known to date, MENs coupled with MPI can be used for mapping electric field activity of the brain at the sub-neuronal level in real time. The potential applications span from prevention and treatment of neurodegenerative diseases to paving the way to fundamental understanding and reverse engineering the brain.

In magnetic hard disk technology, continued scaling of bit density requires higher coercivity and anisotropy media in order to maintain data retention time. This creates a major challenge for scaling the electromagnet-based write head, which is currently being addressed by heat-assisted magnetic recording (HAMR) technology. In this work, we investigate the use of spin transfer torque point contacts induced by spin-polarized current injected from a nanoscale probe tip across a very narrow gap into magnetic media to change magnetization direction. We present our recent experiment using a functional nanoprobe to substitute the disk writer structure. State-ofthe-art He-ion focused ion beam (FIB) trimming was used to develop a nanoscale magnetic structure on top of a tip as shown in Fig 1(A). The standard Ta(5nm)/CoFeB(1nm)/MgO(0.9nm) on tip side and another Ta(5nm)/CoFeB(1nm)/MgO(0.9nm) stack on media side were deposited via sputter deposition and milled. The IV characteristics are shown in Fig 1(B) and show magnetization switching of the media through MTJ-type probing. The magnetization change of practical medial structures which consist of sub-10-nm L1(0) ordered FePt structures was observed using the fixed layer of the tip as shown in Fig 1(C). This result suggests a completely new approach for hard disk writing and could pave the way to the field of magnetic recording with ultra-small, ultra-high density, and ultra-fast data rate further.

© 2018 Author(s). Spin-transfer torque magnetic tunneling junction devices capable of a multilevel three-dimensional (3D) information processing are studied in the sub-20-nm size range. The devices are built using He+ and Ne+ focused ion beam etching. It has been demonstrated that due to their extreme scalability and energy efficiency, these devices can significantly reduce the device footprint compared to the modern CMOS approaches and add advanced features in a 3D stack with a sub-20-nm size using a spin polarized current.

Aim: The in vivo study on imprinting control region mice aims to show that magnetoelectric nanoparticles may directly couple the intrinsic neural activity-induced electric fields with external magnetic fields. Methods: Approximately 10 µg of CoFe2O4–BaTiO3 30-nm nanoparticles have been intravenously administrated through a tail vein and forced to cross the blood–brain barrier via a d.c. field gradient of 3000 Oe/cm. A surgically attached two-channel electroencephalography headmount has directly measured the modulation of intrinsic electric waveforms by an external a.c. 100-Oe magnetic field in a frequency range of 0–20 Hz. Results: The modulated signal has reached the strength comparable to that due the regular neural activity. Conclusion: The study opens a pathway to use multifunctional nanoparticles to control intrinsic fields deep in the brain.

© 2017 IEEE. Nanomagnetic devices in -The sub-5-nm size range still do not exist, not only because of many fabrication and characterization challenges but also because of -The poorly understood physics in this size range. Previous experimental studies from various groups have shown that -The spin relaxation time can be increased by orders of magnitude with this size reduction. The increased spin lifetime leads to a combination of effects such as spin accumulation and tunneling magnetoresistance enhancement which in turn can significantly and favorably affect -The device performance [1]. The goal of this study is to exploit this new physics through fabrication and testing of magnetic tunneling junction (MTJ) devices with a characteristic size of below 5 nm. To achieve this goal, we integrate magnetic nanoparticles into MTJ structures and measure -Their key properties such as I-V curves and magnetoresistance dependencies. The nanoparticles, with sizes ranging from below 2 to over 10 nm, are made of -The ferrimagnetic spinel ferrite CoFe2O4 using co-precipitation chemistry. It has been -Theoretically predicted that -These nanoparticles become half-metallic in this size range and thus can lead to unprecedented high magnetoresistance values. Indeed, -The nanodevices under study display spin-filtering properties, as confirmed through measurements of magnetoresistance and I-V dependences [2]. This paper summarizes -The measured room-temperature anomalous magnetoresistance and I-V curves with a Coulomb-staircase-like dependence characteristic of a single-electron transport.

Aim: The biodistribution and clearance of magnetoelectric nanoparticles (MENs) in a mouse model was studied through electron energy dispersive spectroscopy. Materials & methods: This approach allows for detection of nanoparticles (NPs) in tissues with the spatial resolution of scanning electron microscopy, does not require any tissue-sensitive staining and is not limited to MENs. Results: The size-dependent biodistribution of intravenously administrated MENs was measured in vital organs such as the kidneys, liver, spleen, lungs and brain at four different postinjection times including 1 day, 1 week, 4 and 8 weeks, respectively. Conclusion: The smallest NPs, 10-nm MENs, were cleared relatively rapidly and uniformly across the organs, while the clearance of the larger NPs, 100- and 600-nm MENs, was highly nonlinear with time and nonuniform across the organs.

Magnetoelectric (ME) nanoparticles (MENs) intrinsically couple magnetic and electric fields. Using them as nuclear magnetic resonance (NMR) sensitive nanoprobes adds another dimension for NMR detection of biological cells based on the cell type and corresponding particle association with the cell. Based on ME property, for the first time we show that MENs can distinguish different cancer cells among themselves as well as from their normal counterparts. The core-shell nanoparticles are 30 nm in size and were not superparamagnetic. Due to presence of the ME effect, these nanoparticles can significantly enhance the electric field configuration on the cell membrane which serves as a signature characteristic depending on the cancer cell type and progression stage. This was clearly observed by a significant change in the NMR absorption spectra of cells incubated with MENs. In contrast, conventional cobalt ferrite magnetic nanoparticles (MNPs) did not show any change in the NMR absorption spectra. We conclude that different membrane properties of cells which result in distinct MEN organization and the minimization of electrical energy due to particle binding to the cells contribute to the NMR signal. The nanoprobe based NMR spectroscopy has the potential to enable rapid screening of cancers and impact next-generation cancer diagnostic exams.

To realize the potential of magnetic tunnel junctions (MTJs) for high-density non-volatile memory and non-volatile logic, the critical current to switch the magnetization must be lowered. This paper presents a simulation study of a new structure of perpendicular MTJs (pMTJs) which divides the fixed layer into two coupling parts. We investigate the TMR and the critical current density of this new pMTJ by micromagnetic simulation using OOMMF for various cases. The simulation results show that this new structure pMTJ has lower critical current and shorter switching time compared to the conventional three-layer MTJs.

In the magnetic hard disk drive industry, a continuous increase in the recording density requires higher anisotropy media in order to maintain thermal stability. However, further advances by scaling have run into a stumbling block due to limitations on the required magnetic fields, particularly for writing, which is currently being addressed by alternative approaches such as heat-assisted magnetic recording and microwave-assisted magnetic recording technologies. In this work, we investigate and demonstrate another alternative approach which is based on the effect of the spin transfer torque (STT). The approach uses tunneling spin-polarized currents, instead of magnetic fields, between a nanoscale magnetic probe and a magnetic recording media, both with a perpendicular anisotropy. Writing is performed by spin polarized electrons injected from the probe into the media, due to the STT effect. Reading is produced by the tunneling magnetoresistance (TMR) effect between the two magnetic layers, in the probe writer and the media substrate, respectively. The energy-efficient switching, with an energy of 3.1 MA/cm2, is confirmed through the TMR and the magneto-optical Kerr effect. The demonstrated STT-based magnetic recording overcomes the magnetic field limitations to both writing and reading and thus paves the way for the next-generation energy-efficient and extremely high-density recording.

Using magnetoelectric nanoparticles (MENs) for targeted drug delivery and on-demand, field-controlled release can overcome the control challenges of the conventional delivery approaches. The magnetoelectric effect provides a new way to use an external magnetic field to remotely control the intrinsic electric fields that govern the binding forces between the functionalized surface of the MEN and the drug load. Here, a study is reported in which the composition of the intermediate functionalized layer is tailored to control not only the toxicity of the new nanoparticles but also the threshold magnetic field for the dissociation of the drug from 30-nm CoFe2O4–BaTiO3 core–shell MENs in a controllably wide field range, from below 10 to over 200 Oe, as required to facilitate superficial, intermediate, and deep-tissue drug delivery. Paclitaxel is used as a test drug. Specific experiments are described to maintain low toxicity levels and to achieve controllable dissociation of the drug molecules from the MENs' surface at three different subranges—low ( 200 Oe)—by selecting the following 2-nm intermediate layers: i) glycerol monooleate (GMO), ii) Tween-20, and iii) ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). Field-dependent FTIR, absorption spectra, atomic force microscopy, magnetometry analysis, zeta-potential measurements, and blood circulation experiments are used to study the described functionalization effects.

It is a challenge to eradicate tumor cells while sparing normal cells. We used magnetoelectric nanoparticles (MENs) to control drug delivery and release. The physics is due to electric-field interactions (i) between MENs and a drug and (ii) between drug-loaded MENs and cells. MENs distinguish cancer cells from normal cells through the membrane’s electric properties; cancer cells have a significantly smaller threshold field to induce electroporation. In vitro and in vivo studies (nude mice with SKOV-3 xenografts) showed that (i) drug (paclitaxel (PTX)) could be attached to MENs (30-nm CoFe2O4@BaTiO3 nanostructures) through surface functionalization to avoid its premature release, (ii) drug-loaded MENs could be delivered into cancer cells via application of a d.c. field (~100 Oe), and (iii) the drug could be released off MENs on demand via application of an a.c. field (~50 Oe, 100 Hz). The cell lysate content was measured with scanning probe microscopy and spectrophotometry. MENs and control ferromagnetic and polymer nanoparticles conjugated with HER2-neu antibodies, all loaded with PTX were weekly administrated intravenously. Only the mice treated with PTX-loaded MENs (15/200 μg) in a field for three months were completely cured, as confirmed through infrared imaging and post-euthanasia histology studies via energy-dispersive spectroscopy and immunohistochemistry.

L1 0 -FePt thin films were deposited on silicon substrates with the structure of Si/CrRu/MgO/FePt. The magnetic and microstructural properties were optimized by varying the FePt sputter pressure and temperature, as well as the thicknesses of all three layers. High coercivity films greater than 1.8 T were grown when the FePt sputter pressure was at 1.33 Pa with a thickness of only 4 nm, on CrRu and MgO underlayers as thin as 10 nm and 2 nm, respectively.

We present an experimental study on ultra-dense 3-D non-volatile magnetic universal logic gates with reconfigurable AND and OR functions. A four-layer magnetic structure with a net thickness of less than 30 nm is employed as a study illustration of a highly scalable magnetic logic device. In the device, the magnetic state of the top output "soft" layer depends on the magnetic states of the remaining three "hard" layers used as two input and one reset layers, respectively. To build vertically oriented magnetic devices with a gradient of the coercivity and the magnetization across the thickness, we use Co/Pd multilayers sputter-deposited via a combinatorial synthesis. Through a focused magneto-optical Kerr effect (F-MOKE) study, we relate input and output states in the 4-layer logic device to shoulders on major and minor M-H hysteresis loops. We use magnetic force microscopy (MFM) to identify magnetic logic operations.

The effects of substrate Ar-ion milling and Ta adhesion layer on the microstructural and magnetic properties of L1(0)-FePt films prepared on Si, SiO2, and glass substrates were investigated. It was discovered that the relatively large in-plane surface roughness of CrRu/MgO/FePt films deposited on Si substrates was due to the deformation of the CrRu layer when the composition was heated to 550 degrees C. More than an order of magnitude improvement for the in-plane surface roughness was achieved when substrate Ar-ion milling or Ta adhesion layer was incorporated into the process. While the Ta adhesion layer proved to be detrimental to the (200) growth of the CrRu layer, optimal FePt film properties with coercivity values larger than 2 Tesla and out-of-plane roughness less than 1 nm were achieved when only substrate Ar-ion milling was implemented.

International audience; Graphene displays unprecedented electronic properties including room-temperature ballistic transport and quantum conductance, and because of its small spin-orbit interaction, graphene has the potential to function as the building block of future spintronic devices. Theoretical calculations indicate that a defective graphene sheet will be simultaneously semiconducting and magnetic; thus it would act as a room-temperature magnetic semiconductor. Recently, ferromagnetic ordering at room temperature has been observed by magnetometry measurements on bulk samples of reduced graphene oxide.

The effect of double erasure on Monolayer Bacteriorhodopsin (BR) protein films after photonic excitation to the ultra stable Q-state is studied. It was found that the pronounced emission of 755 nm light occurs only as the protein is made to transition from the Q-state to the ground state via irradiation with blue light. Requirements for the implementation of a next generation Protein-Based Memory (PBM) device utilizing monolayer BR films are considered. The finite element method was used to simulate the optical intensity distribution of nano-aperture waveguides for Red (650 nm), Green (510 nm) and Blue (475 nm) light to analyze the utility of nanoaperture transducers for use in a Protein Based Memory device. The minimum output power required to induce a photochromic transition in BR is calculated to be between 20 nW and 27 nW on a 30 nm spot depending upon the operating wavelength.

In-situ fluid-cell AFM has been used to investigate the corrosion mechanisms of TaZrO and BCN thin films as protective coatings for magnetic media. This technique allows for real-time, in-situ monitoring of corrosion with nanometer resolution. The technique proved valuable in revealing peculiarities that cannot be detected using conventional techniques. In contrast to the nitride films, the results point to defect-based diffusion type corrosion mechanism in the oxide films.

To enable patient- and disease-specific diagnostic and treatment at the intracellular level in real time, it is imperative to engineer a perfect way to locally stimulate selected individual neurons, navigate and dispense a cargo of biomolecules into damaged cells or image sites with relatively high efficacy and with adequate spatial and temporal resolutions. Significant progress has been made using biotechnology; especially with the development of bioinformatics, there are endless molecular databases to identify biomolecules to target almost any disease-specific biomarker. Conversely, the technobiology approach that exploits advanced engineering to control underlying molecular mechanisms to recover biosystem’s energy states at the molecular level as well as at the level of the entire network of cells (i.e., the internet of the human body) is still in its early research stage. The recently developed magnetoelectric nanoparticles (MENPs) provide a tool to enable the unique capabilities of technobiology. Using exemplary studies that could potentially lead to future pinpoint treatment and prevention of cancer, neurodegenerative diseases, and HIV, this article discusses how MENPs could become a vital enabling tool of technobiology.