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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.

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.

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.

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.

© 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.

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.

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.

We use ion beam proximity lithography (IBPL) to produce 4 mm times 4 mm arrays of 220-nm dots in perpendicularly oriented Co/Pd multilayered media. A novel technique of overlapping neighbors is used with IBPL to generate samples with controllable size distribution sigmaD of the nanoarrays. The switching field distribution sigmaHcr/HCr is measured for each sample before and after irradiation, and a linear relationship is experimentally found between sigmaHcr/HCr and sigmaD. Empirical calculations support our determination that self-demagnetization fields are responsible for a portion of the switching field distribution. Using the zero intercept of the experimental data, we find the inherent anisotropy distribution in the Co/Pd samples is on the order of 10%. We further irradiate the samples with He+ ions to alter the anisotropy and better understand the role of shape anisotropy. As interface anisotropy is reduced in the Co/Pd bit-patterned medium (BPM) samples, shape anisotropy has a much greater contribution on the switching field distribution of the BPM samples.

Today, conventional magnetic recording schemes are coming to an end because of the superparamagnetic limit. Heat-assisted magnetic recording (HAMR) may ultimately extend data densities beyond 1 TB/in2. HAMR systems utilize the phenomenon during which the magnetic properties of the recording media could be locally modified via heating (optionally, by an optical source in the near field) to temperature in the vicinity of the Curie value of the media material. As a result, heat induced by the optical source can temporarily reduce the magnetic coercivity of high anisotropy material to a level attainable by the magnetic writing head, thus making it feasible to record on relatively small ultra-high anisotropy (and thermally stable) grains, consequently enhancing the areal density dramatically. The key challenge is to develop a near-field transducer capable of delivering over 50 nW into a spot diameter of 30 nm. Traditional fiber schemes are barely capable of 0.1 nW. To resolve the issue, a laser diode could be placed with the emitting edge only a few nanometers away from the recording media. The light can propagate through a nanoaperture on the surface of an aluminum-coated emitting edge. This paper will present an experimental study of recording characteristics of various near-field transducers fabricated via focused ion beam (FIB). To count the number of photons emitted in the near field, a scanning near-field optical microscopy system has been implemented. The experiments indicate that the FIB-fabricated transducers could deliver power of over a few microwatt into a 30-nm spot (Fig. 7).

Magnetic logic devices have advantages of non-volatility, radiation hardness, scalability down to the sub-5-nm range, and three-dimensional (3D) integration capability. Despite these advantages, nanomagnetic applications for information processing are limited today. The main stumbling block is the inadequately high energy required to switch information states in the spin-based nanodevices. Recently, the spin-transfer torque (STT) effect has been introduced as a promising solution [1-2]. In STT magnetic tunneling junctions (MTJs), using a spin-polarized electric current to switch magnetic states has the potential to solve the energy problem. However, the switching current density on the order of 1 MA/cm2 in the current STT-MTJ devices, with the smallest reported to date characteristic cross-sectional size on the order of 10 nm, still remains inadequately high for enabling a wide range of information processing applications [3-4]. For the technology to be competitive in the near future, it is critical to show that it could be favorably scaled into the sub-10-nm range. On a positive note, due to a new physics in this previously poorly explored size range, nanomagnetic devices may display promising characteristics that can make them superior to their semiconductor counterparts. In this size range, the underlying spin physics is due to the surface as much as it is due the volume. As a result, the effective thermal reservoir that absorbs spin excitations is substantially reduced, which in turn leads to a reduced spin damping and consequently to a reduced switching current density. Hence, the current study to understand the junction size dependence of the spin switching current is timely. This paper presents the key results of this study.

Summary form only given. It is commonly believed that to achieve high recording performance, the gap between the leading and trailing poles in a single pole head (SPH) has to be long with respect to the . Such an SPH is referred to as type I. An SPH in which the gap length is small air bearing surface (ABS) to soft underlayer (SUL) spacing with respect to SUL-to-ABS spacing is referred to as type II. In this work, the recording characteristics of type II and type I SPHs are compared. For clarity, SPH and RH imply the presence and the absence of a SUL, respectively. It should be stressed that recording on a medium with a RH is fundamentally different from recording with a SPH. In recording with a SPH, the writing is done by the trailing edge of the trailing pole. This is in contrast to recording with a RH, in which the writing is done by the trailing edge of the gap. A conventional RH used to write onto a medium with a SUL acts as a type II SPH.

In this paper, we describe techniques for the magnetic characterization of perpendicular recording media. Such measurements made using traditional techniques, such as the vibrating sample magnetometry (VSM) and alternating gradient force magnetometer (AGFM), have to be corrected for the sample shape demagnetizing factor, which is often found not to be equal to -4/spl pi/. For measurements other than the simple hysteresis loop, such as remanence curves, this correction must be carried out in real time and we describe the method by which this can be achieved and the process for achieving the correct demagnetization of perpendicular films prior to measurements of the isothermal remanent magnetization curve. A further complication is that real perpendicular media have a soft underlayer beneath the recording layer, which swamps and confuses signals from instruments such as VSM or AGFM. Hence, we describe the construction and use of a magnetooptical Kerr effect magnetometer, which does not penetrate significantly into the soft layer and enables the perpendicular layer to be measured independently. We describe the properties of a traditional alloy perpendicular medium and a Co-Pd multilayer system, which in the latter case exhibits multiple switching behavior. We also address the issue of the effect of the soft underlayer on the coupling in similar longitudinal films and find that the presence of the underlayer induces significant additional coupling effects that may well give rise to an increase in noise in recorded signals.

Focused ion beam (FIB) applications in the field of nanoscale probe recording are explored. A detailed description of how to use FIBs for trimming longitudinal and perpendicular magnetic recording and playback devices to dimensions of less than 100 nm is presented. An experiment was conducted to demonstrate that the magnetoresistive property of a read element, e.g. a giant-magnetoresistive sensor, strongly depends on the focused ion current and the beam accelerating voltage.

Introduction: Delivering a drug specifically into the tumor cell past its membrane and then releasing the drug into the tumor cells without affecting the normal cells remains a formidable challenge. Unlike any other nanoparticles, magnetoelectric nanoparticles (MENs) display a non-zero magnetoelectric (ME) effect and thus present a unique capability to use external magnetic fields to control intrinsic electric fields associated with cell membranes and the interaction between MENs and therapeutic loads. Because cancer and normal cells of the same type have different electric properties, MENs is used for high-specificity targeted delivery. An a.c. magnetic field is used to trigger drug release off the nanoparticles. Brief Methods: 30-nm CoFe2O4-BaTiO3 core shell MENs, with a magnetization of 1 emu/g, a coercivity of 300 Oe, and a ME coefficient of 10-100 mV cm-1 Oe-1 were prepared with a coprecipitation process. MENs were coated with fluorescein isothiocyanate to monitor their intra-cellular transport through a high-contrast confocal microscopy. Three cancer cell lines including Skov-3 (Ovarian adenocarcinoma), U87-MG (Glioblastoma), and MCF-7A (Breast adenocarcinoma), and two normal cell lines including brain endothelial cells (Brain EC) and ovarian cells HOMEC were cultured at 37°C. The transport of MENs loaded with drugs, peptides, and RNAs through the cell membranes and the consequent release of the load under different d.c. and a.c. magnetic fields were studied through confocal microscopy and photoabsorption spectroscopy, respectively. Trypan-blue viability count was used to assess cell growth inhibition under different study conditions. Atomic force microscopy of the cell membranes was conducted to understand the interaction between the nanoparticles and the cells. Summary of new data: Comparison of MENs with purely magnetic iron oxide nanoparticles showed that the penetration through the cancer cell membrane could be achieved only with MENs. It took d.c. fields of 100 Oe and over 1000 Oe to nanoelectroporate the membranes of SKOV-3 and HOMEC cell lines, respectively. An a.c. magnetic field with a strength of 50 Oe and a near-d.c. frequency of 100 Hz was sufficient to enable release of a therapeutic load off MENs. All the cancer cell lines under study showed membrane penetration threshold d.c. fields at least a factor of ten smaller compared to their normal counterparts. Conclusion: MENs displayed unique capabilities for externally controlled high-specificity targeted anticancer drug delivery and release on demand via application of d.c. and a.c. magnetic fields, respectively. Because MENs rely on a physical mechanism rather than antibody-mediated delivery, they can be used for high specificity delivery and high-efficacy controlled release of a broad range of therapeutic loads including drugs, peptides, and RNAs to treat many different cancers. Citation Format: Emmanuel Stimphil, Abhi Nagesetti, Tiffanie S. Stewart, Alexa Rodzinski, Rakesh Guduru, Ping Liang, Carolyn Runowicz, Sakhrat Khizroev. Magnetoelectric nanoparticles for high-specificity treatment of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2199. doi:10.1158/1538-7445.AM2017-2199

In regard to cancer therapy, magnetoelectric nanoparticles (MENs) have proven to be in a class of its own when compared to any other nanoparticle type. Like conventional magnetic nanoparticles, they can be used for externally controlled drug delivery via application of a magnetic field gradient and image-guided delivery. However, unlike conventional nanoparticles, due to the presence of a non-zero magnetoelectric effect, MENs provide a unique mix of important properties to address key challenges in modern cancer therapy: (i) a targeting mechanism driven by a physical force rather than antibody matching, (ii) a high-specificity delivery to enhance the cellular uptake of therapeutic drugs across the cancer cell membranes only, while sparing normal cells, (iii) an externally controlled mechanism to release drugs on demand, and (iv) a capability for image guided precision medicine. These properties separate MEN-based targeted delivery from traditional biotechnology approaches and lay a foundation for the comp...

A scanning magnetoresistance microscope (SMRM) was used to enable recording experiments on bit patterned media prototypes not yet suitable for spin-stand evaluation. The SMRM generates a 2D playback response of the media by “dragging” a recording head across the sample using a piezoelectric nanopositioner. A large-scale parameter optimization technique is applied to extract relevant parameters such as pulse amplitude, pulse width, and pulse position from the 2D playback response. The parameters were analyzed to learn that the pulse response of our recording head cannot be accurately modeled as a Gaussian function. The error in the optimized parameters is dominated by intertrack interference and to a lesser extent measurement resolution and thermal drift.

Using 3D modeling, guidelines for ultra-high density perpendicular recording were defined. The concepts developed to choose dimensions and materials were verified experimentally using MFM and spin-stand experiments with a 60 nm wide focused ion beam (FIB) trimmed head.

The effect of the relative head-to-medium velocity on the switching dynamics of individual grains is studied using the Landau-Lifshitz-Gilbert equation of motion. The coercive field of a grain may increase or decrease with velocity depending on the direction of crystal anisotropy. An asymmetry is present and the coercivity of an ensemble of grains with random in-plane anisotropy is found to increase, in agreement with measurements on a CoCr longitudinal magnetic recording medium.

CoCrPtTa/Ti bilayer thin films have been sputter deposited onto both glass and Al substrates under high sputtering rate in a manufacturing environment. From microstructure and magnetic property studies, it is found that Cr segregation and stacking fault density are the two major issues in obtaining high quality perpendicular media. (0002) texture orientation spread and c lattice parameter remain almost constant within the variation range of the deposition parameters, though there is a small distinction between the media on glass and those on Al substrates.

This paper reviews the material properties of Fe-AlN high moment soft magnetic material, and discusses the design, fabrication and performance of write heads using this material. These write heads comprise two designs. The first had FeAlN for both top and bottom poles. The second incorporated a 0.2 /spl mu/m thick FeAlN layer underneath an electroplated Ni/sub 80/Fe/sub 20/ top pole. The first type of head was tested on high coercivity (3300 Oe) media. Wide and narrow track width heads saturated the media at the highest tested write frequency of 225 MHz. At 90 MHz, they exhibited overwrite approaching 50 dB and hard transition peak shift of less than 1 nm. This overwrite was 7-9 dB higher than that measured for heads with Ni/sub 45/Fe/sub 55/ top poles. A 50% amplitude roll-off density (D/sub 50/) of up to 6300 fc/mm was also measured, using a narrow gap MR read sensor. However, reverse dc erase noise measurements indicated significantly lower head efficiency compared to NiFe heads, as has been observed previously. The second type of head on the other hand exhibited /spl sim/5 dB better overwrite compared to a Ni/sub 80/Fe/sub 20/ head, without a large loss in head efficiency.

Micromagnetic modeling based on LLG formalism was used to study the magnetization reversal processes in patterned recording layer. The write fields generated by an idealized single pole write head with a uniformly magnetized air-bearing surface (ABS) were used. The applied write field is highly nonuniform within a bit, making consistent comparison based on its values difficult. The effects of the bit geometry, medium thickness, head/medium magnetic spacing (flying height), ABS geometry, the effects of neighboring bits on magnetization reversal, and the sensitivity of the write process to non-zero write misregistration (WMR) were investigated. It was shown that the larger ABS cross-section heads generate stronger write fields resulting in a capability of using higher anisotropy/better thermal stability media materials. Also, the sensitivity on WMR is weaker for larger ABS cross-section heads simplifying the optimization of a recording system design.

Perpendicular recording may be the most viable, near future, replacement for the longitudinal core technology in ultrahigh-density magnetic disk storage. Central to this mode of recording is a soft underlayer (SUL) which facilitates flux flow between writer poles, and is responsible for an effective increase in recording field. However, there are controversies concerning the effectiveness and limitations of using soft underlayers; among which are readback noise and inadequate switching torque. Patterned SUL is proposed as a new and viable approach to SUL limitations in perpendicular media, with improved system performance. Numerical models have been developed using commercially available FEM and BEM software suites (ANSYS and Ampere) to demonstrate key advantages of patterned SUL in perpendicular media

Magnetoresistive playback off bit patterned magnetic recording media is studied. Three playback configurations are compared: not shielded sensors, shielded sensors commonly used in magnetic recording systems, and shielded differential sensors. Influence of patterned medium parameters including bit-filling ratio, bit shape, bit position jitter, bit-size variation on the playback signal is studied. Playback signal amplitude, D50, and signal-to-noise ratio are used to compare different playback sensor configurations. It is found that in general, shielded differential readers offer superior performance as compared to both shielded single sensor readers and not shielded readers

Nature Communications 4: Article number: 1707 (2013); Published: 16 April 2013; Updated: 25 October 2013. This Article contains typographical errors in the second paragraph of the Results section and the first paragraph of the Discussion section. In each case the magneto-electric (ME) coefficient ofthe nanoparticles was incorrectly cited in V cm −1 Oe −1, whereas the value should have been 100 mV cm −1 Oe −1.

The nanotechnology capable of high-specificity targeted delivery of anti-neoplastic drugs would be a significant breakthrough in Cancer in general and Ovarian Cancer in particular. We addressed this challenge through a new physical concept that exploited (i) the difference in the membrane electric properties between the tumor and healthy cells and (ii) the capability of magneto-electric nanoparticles (MENs) to serve as nanosized converters of remote magnetic field energy into the MENs' intrinsic electric field energy. This capability allows to remotely control the membrane electric fields and consequently trigger high-specificity drug uptake through creation of localized nano-electroporation sites. In in-vitro studies on human ovarian carcinoma cell (SKOV-3) and healthy cell (HOMEC) lines, we applied a 30-Oe d.c. field to trigger high-specificity uptake of paclitaxel loaded on 30-nm CoFe2O4@BaTiO3 MENs. The drug penetrated through the membrane and completely eradicated the tumor within 24 hours without affecting the normal cells.