Magnetic field pattern synthesis and its application in targeted drug delivery: Design and implementation

A new synthesis method for complex electric field patterning using a multichannel dense array system with applications in low-intensity noninvasive neuromodulation

Multichannel coil array systems offer precise spatiotemporal electronic steering and patterning of electric and magnetic fields without the physical movement of coils or magnets. This capability could potentially benefit a wide range of biomagnetic applications such as low-intensity noninvasive neuromodulation or magnetic drug delivery. In this regard, the objective of this work is to develop a unique synthesis method, that enabled by a multichannel dense array system, generates complex current pattern distributions not previously reported in the literature. Simulations and experimental results verify that highly curved or irregular (e.g., zig-zag) patterns at singular and multiple sites can be efficiently formed using this method. The synthesis method is composed of three primary components; a pixel cell (basic unit of pattern formation), a template array ("virtual array": code that disseminates the coil current weights to the "physical" dense array), and a hexagonal coordinate system. Low-intensity or low-field magnetic stimulation is identified as a potential application that could benefit from this work in the future and as such is used as an example to frame the research.

ANTITUMOR EFFECT OF ELECTROMAGNETIC FIELDS AND THEIR EFFECT ON PAIN IN EXPERIMENTAL AND CLINICAL ONCOLOGY

The review examined and analyzed scientific publications on the effect of electromagnetic fields (EMF) on various sys­tems of the human body and animals with tumors, as well as on pain in the experiment and the clinic. The theoretical foundations and practical results of the use of EMF in various modulations and modes in the goals and objectives of oncology, including how to optimize the process of anesthesia and correct the vital activity of the body's functional systems with a tumor, are consecrated. Information is given on possible physicochemical effects, features, and mecha­nisms of therapeutic influence at various levels of a living organism. The ability of electromagnetic waves to transfer in­formation both within a single biosystem and at the level of a whole living organism with a tumor is shown. Studies of combined action of EMF and chemotherapy were analyzed. It has been established that there are experimental prerequisites for using this factor in order to induce changes in the permeability of the membranes of tumor cells by in­creasing the internalization of chemotherapeutic agents and, thus, enhance the antitumor effect. The role of EMF in the induction of apoptosis in tumor cells is shown. It has been shown that chemotherapy together with electromagnetic fields induces apoptosis and has an inhibitory effect on DNA synthesis in osteosarcoma cells, breast cancer, colon cancer, melanoma and other tumors. The role of magnetic fields in order to enhance the analgesic effect was investigated. The analgesic effect is due to the cessation or weakening of nerve impulses from the painful focus due to the elimination of hypoxia, the improvement of microcirculation, and the reduction of edema, it has been shown. Transcranial magnetic therapy is used as an analgesic tool in onconurology. The therapeutic anti-pain effect is associated with the stimulation of the antinociceptive system, an increase in the synthesis of natural analgesics — endorphins with their subsequent release into the cerebrospinal fluid and blood. As it has already been shown, with the increase in the intensity of pain and its duration, all indicators of the quality of life and the results of treatment of the patient deteriorate, so the search for ways to improve the antitumor effectiveness of specialized treatment and eliminate the causes that prevent their im­plementation continue to be relevant and in demand.

Use of magnetic fields and nanoparticles to trigger drug release and improve tumor targeting

Drug delivery strategies aim to maximize a drug's therapeutic index by increasing the concentration of drug at target sites while minimizing delivery to off-target tissues. Because biological tissues are minimally responsive to magnetic fields, there has been a great deal of interest in using magnetic nanoparticles in combination with applied magnetic fields to selectively control the accumulation and release of drug in target tissues while minimizing the impact on surrounding tissue. In particular, spatially variant magnetic fields have been used to encourage accumulation of drug-loaded magnetic nanoparticles at target sites, while time-variant magnetic fields have been used to induce drug release from thermally sensitive nanocarriers. In this review, we discuss nanoparticle formulations and approaches that have been developed for magnetic targeting and/or magnetically induced drug release, as well as ongoing challenges in using magnetism for therapeutic applications. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

A Vascular Thrombus Therapy Method Based on Magnetic-Induced Vibration

A vascular thrombus therapy method based on magnetic-induced vibration is presented. It is a mechanicalway of removing vascular thrombus that adopts the combined use of two concepts, namely (i) magnetic-induced vibration of magnetostrictive materials and (ii) changes in physical form of thrombus under high-frequency impact and vibration. This method has many advantages that (i) eliminate the side effects of drug treatment, (ii) reduce the complexity of traditional mechanical method, and (iii) improve the reliability of treatment. Practical results obtained from the simulations and experiments are included. They verify the proposed system and indicate that this method can effectively treat vascular thrombus and reduce patient's suffering and costs. Bioelectromagnetics. 2019;40:391-401. © 2019 Bioelectromagnetics Society.

Single-Sided Near-Field Wireless Power Transfer by A Three-Dimensional Coil Array

Wirelessly powered medical microrobots are often driven or localized by magnetic resonance imaging coils, whose signal-to-noise ratio is easily affected by the power transmitter coils that supply the microrobot. A controlled single-sided wireless power transmitter can enhance the imaging quality and suppress the radiation leakage. This paper presents a new form of electromagnet which automatically cancels the magnetic field to the back lobes by replacing the traditional circular coils with a three-dimensional (3D) coil scheme inspired by a generalized form of Halbach arrays. It is shown that, along with the miniaturization of the transmitter system, it allows for improved magnetic field intensity in the target side. Measurement of the produced magnetic patterns verifies that the power transfer to the back lobe is 15-fold smaller compared to the corresponding distance on the main lobe side, whilst maintaining a powering efficiency similar to that of conventional planar coils. To show the application of the proposed array, a wireless charging pad with an effective powering area of 144 cm² is fabricated on 3D-assembled printed circuit boards. This 3D structure obviates the need for traditional magnetic shield materials that place limitations on the working frequency and suffer from non-linearity and hysteresis effects.

A review on the use of magnetic fields and ultrasound for non-invasive cancer treatment

Current popular cancer treatment options, include tumor surgery, chemotherapy, and hormonal treatment. These treatments are often associated with some inherent limitations. For instances, tumor surgery is not effective in mitigating metastases; the anticancer drugs used for chemotherapy can quickly spread throughout the body and is ineffective in killing metastatic cancer cells. Therefore, several drug delivery systems (DDS) have been developed to target tumor cells, and release active biomolecule at specific site to eliminate the side effects of anticancer drugs. However, common challenges of DDS used for cancer treatment, include poor site-specific accumulation, difficulties in entering the tumor microenvironment, poor metastases and treatment efficiency. In this context, non-invasive cancer treatment approaches, with or without DDS, involving the use of light, heat, magnetic field, electrical field and ultrasound appears to be very attractive. These approaches can potentially improve treatment efficiency, reduce recovery time, eliminate infections and scar formation. In this review we focus on the effects of magnetic fields and ultrasound on cancer cells and their application for cancer treatment in the presence of drugs or DDS.