Brain tumor targeting of magnetic nanoparticles for potential drug delivery: effect of administration route and magnetic field topography

Magnetic nanomaterials mediate precise magnetic therapy

Magnetic nanoparticle (MNP)-mediated precision magnet therapy plays a crucial role in treating various diseases. This therapeutic strategy compensates for the limitations of low spatial resolution and low focusing of magnetic stimulation, and realizes the goal of wireless teletherapy with precise targeting of focal areas. This paper summarizes the preparation methods of magnetic nanomaterials, the properties of magnetic nanoparticles, the biological effects, and the measurement methods for detecting magnetism; discusses the research progress of precision magnetotherapy in the treatment of psychiatric disorders, neurological injuries, metabolic disorders, and bone-related disorders, and looks forward to the future development trend of precision magnet therapy.

Sequential targeting dual-responsive magnetic nanoparticle for improved therapy of lung metastatic breast cancer

Lung metastatic breast cancer is a leading cause of cancer-related death in women and difficult to treat due to non-specific drug delivery. Herein a sequential targeting dual-responsive magnetic nanoparticle was fabricated, where Fe3O4 nanoparticle was used as magnetic core, then sequentially coated with tetraethyl orthosilicate, bis[3-(triethoxy-silyl)propyl] tetrasulfide, and 3-(trimethoxysilyl) propylmethacrylate to afford -C = C- on the surface for further polymerisation with acrylic acid, acryloyl-6-ethylenediamine-6-deoxy-β-cyclodextrin using N, N-bisacryloylcy- stamine as cross-linker, obtaining pH/redox dual-responsive magnetic nanoparticle (MNPs-CD) to delivery doxorubicin (DOX) for suppressing lung metastatic breast cancer. Our results suggested DOX-loaded nanoparticle could target the lung metastases site by sequential targeting, in which they first be delivered to the lung and even the metastatic nodules through size-driven, electrical interaction, and magnetic field-guided mechanisms, then be effectively internalised into the cancer cells followed by intelligently triggering DOX release. MTT analysis demonstrated DOX-loaded nanoparticle exhibited high anti-tumour activity against 4T1 and A549 cells. 4T1 tumour-bearing mice were employed to confirm the higher specific accumulation in lung and improved anti-metastatic therapy efficiency of DOX by focussing an extracorporeal magnetic field on the biological target. Our findings suggested the as-proposed dual-responsive magnetic nanoparticle offered a prerequisite to inhibit lung metastasis of breast cancer tumours.

Magnetically Driven Self-Degrading Zinc-Containing Cystine Microrobots for Treatment of Prostate Cancer

Prostate cancer is the most commonly diagnosed tumor disease in men, and its treatment is still a big challenge in standard oncology therapy. Magnetically actuated microrobots represent the most promising technology in modern nanomedicine, offering the advantage of wireless guidance, effective cell penetration, and non-invasive actuation. Here, new biodegradable magnetically actuated zinc/cystine-based microrobots for in situ treatment of prostate cancer cells are reported. The microrobots are fabricated via metal-ion-mediated self-assembly of the amino acid cystine encapsulating superparamagnetic Fe₃ O₄ nanoparticles (NPs) during the synthesis, which allows their precise manipulation by a rotating magnetic field. Inside the cells, the typical enzymatic reducing environment favors the disassembly of the aminoacidic chemical structure due to the cleavage of cystine disulfide bonds and disruption of non-covalent interactions with the metal ions, as demonstrated by in vitro experiments with reduced nicotinamide adenine dinucleotide (NADH). In this way, the cystine microrobots served for site-specific delivery of Zn²⁺ ions responsible for tumor cell killing via a "Trojan horse effect". This work presents a new concept of cell internalization exploiting robotic systems' self-degradation, proposing a step forward in non-invasive cancer therapy.

The role of tumor model in magnetic targeting of magnetosomes and ultramagnetic liposomes

The combined passive and active targeting of tumoral tissue remains an active and relevant cancer research field. Here, we exploit the properties of two highly magnetic nanomaterials, magnetosomes and ultramagnetic liposomes, in order to magnetically target prostate adenocarcinoma tumors, implanted orthotopically or subcutaneously, to take into account the role of tumor vascularization in the targeting efficiency. Analysis of organ biodistribution in vivo revealed that, for all conditions, both nanomaterials accumulate mostly in the liver and spleen, with an overall low tumor retention. However, both nanomaterials were more readily identified in orthotopic tumors, reflecting their higher tumor vascularization. Additionally, a 2- and 3-fold increase in nanomaterial accumulation was achieved with magnetic targeting. In summary, ultramagnetic nanomaterials show promise mostly in the targeting of highly-vascularized orthotopic murine tumor models.

Development of a Personalised Device for Systemic Magnetic Drug Targeting to Brain Tumours

Delivering therapies to deeply seated brain tumours (BT) is a major clinical challenge. Magnetic drug targeting (MDT) could overcome this by rapidly transporting magnetised drugs directly into BT. We have developed a magnetic device for application in murine BT models using an array of neodymium magnets with a combined strength of 0.7T. In a closed fluidic system, the magnetic device trapped magnetic nanoparticles (MNP) up to distances of 0.8cm. In mice, the magnetic device guided intravenously administered MNP (<50nm) from the circulation into the brain where they localised within mouse BT. Furthermore, MDT of magnetised Temozolomide (TMZmag+) significantly reduced tumour growth and extended mouse survival to 48 days compared to the other treatment groups. Using the same principles, we built a proof of principle scalable magnetic device for human use with a strength of 1.1T. This magnetic device demonstrated trapping of MNP undergoing flow at distances up to 5cm. MDT using our magnetic device provides an opportunity for targeted delivery of magnetised drugs to human BT.

Recent advances in mechanical force-responsive drug delivery systems

Mechanical force responsive drug delivery systems (in terms of mechanical force induced chemical bond breakage or physical structure destabilization) have been recently explored to exhibit a controllable pharmaceutical release behaviour at a molecular level. In comparison with chemical or biological stimulus triggers, mechanical force is not only an external but also an internal stimulus which is closely related to the physiological status of patients. However, although this mechanical force stimulus might be one of the most promising and feasible sources to achieve on-demand pharmaceutical release, current research in this field is still limited. Hence, this tutorial review aims to comprehensively evaluate the recent advances in mechanical force-responsive drug delivery systems based on different types of mechanical force, in terms of direct stimulation by compressive, tensile, and shear force, or indirect/remote stimulation by ultrasound and a magnetic field. Furthermore, the exciting developments and current challenges in this field will also be discussed to provide a blueprint for potential clinical translational research of mechanical force-responsive drug delivery systems.

Blood-brain barrier crossing using magnetic stimulated nanoparticles

Due to the low permeability and high selectivity of the blood-brain barrier (BBB), existing brain therapeutic technologies are limited by the inefficient BBB crossing of conventional drugs. Magnetic nanoparticles (MNPs) have shown great potential as nano-carriers for efficient BBB crossing under the external static magnetic field (SMF). To quantify the impact of SMF on MNPs' in vivo dynamics towards BBB crossing, we developed a physiologically based pharmacokinetic (PBPK) model for intraperitoneal (IP) injected superparamagnetic iron oxide nanoparticles coated by gold and conjugated with poly (ethylene glycol) (PEG) (SPIO-Au-PEG NPs) in mice. Unlike most reported PBPK models that ignore brain permeability, we first obtained the brain permeabilities with and without SMF by determining the concentration of SPIO-Au-PEG NPs in the cerebral blood and brain tissue. This concentration in the brain was simulated by the advection-diffusion equations and was numerically solved in COMSOL Multiphysics. The results from the PBPK model after incorporating the brain permeability showed a good agreement (regression coefficient R² = 0.848) with the in vivo results, verifying the capability of using the proposed PBPK model to predict the in vivo biodistribution of SPIO-Au-PEG NPs under the exposure to SMF. Furthermore, the in vivo results revealed that the distribution coefficient from blood to brain under the exposure to SMF (4.01%) is slightly better than the control group (3.68%). In addition, the modification of SPIO-Au-PEG NPs with insulin (SPIO-Au-PEG-insulin) showed an improvement of the brain bioavailability by 24.47% in comparison to the non-insulin group. With the SMF stimulation, the brain bioavailability of SPIO-Au-PEG-insulin was further improved by 3.91% compared to the group without SMF. The PBPK model and in vivo validation in this paper lay a solid foundation for future study on non-invasive targeted drug delivery to the brain.

An Overview of Nanotechnologies for Drug Delivery to the Brain

Drug delivery to the brain has been one of the toughest challenges researchers have faced to develop effective treatments for brain diseases. Owing to the blood–brain barrier (BBB), only a small portion of administered drug can reach the brain. A consequence of that is the need to administer a higher dose of the drug, which, expectedly, leads to a variety of unwanted side effects. Research in a variety of different fields has been underway for the past couple of decades to address this very serious and frequently lethal problem. One area of research that has produced optimistic results in recent years is nanomedicine. Nanomedicine is the science birthed by fusing the fields of nanotechnology, chemistry and medicine into one. Many different types of nanomedicine-based drug-delivery systems are currently being studied for the sole purpose of improved drug delivery to the brain. This review puts together and briefly summarizes some of the major breakthroughs in this crusade. Inorganic nanoparticle-based drug-delivery systems, such as gold nanoparticles and magnetic nanoparticles, are discussed, as well as some organic nanoparticulate systems. Amongst the organic drug-delivery nanosystems, polymeric micelles and dendrimers are discussed briefly and solid polymeric nanoparticles are explored in detail.

Magnetic implants in vivo guiding sorafenib liver delivery by superparamagnetic solid lipid nanoparticles

HYPOTHESIS

Solid lipid nanoparticles (SLNs), co-encapsulating superparamagnetic iron oxide nanoparticles and sorafenib, have been exploited for magnetic-guided drug delivery to the liver. Two different magnetic configurations, both comprising two small magnets, were under-skin implanted to investigate the effect of the magnetic field topology on the magnetic SLNP accumulation in liver tissues. A preliminary simulation analysis was performed to predict the magnetic field topography for each tested configuration.

EXPERIMENTS

SLNs were prepared using a hot homogenization approach and characterized using complementary techniques. Their in vitro biological behavior was assessed in HepG-2 liver cancer cells; wild-type mice were used for the in vivo study. The magnet configuration that resulted in a higher magnetic targeting efficiency was investigated by evaluating the iron content in homogenated murine liver tissues.

FINDINGS

SLNs, characterized by an average size smaller than 200 nm, retained their superparamagnetic behavior and relevant molecular resonance imaging properties as negative contrast agents. The evaluation of iron accumulation in the liver tissues was consistent with the magnetic induction profile of each magnet configuration, concurring with the results predicted by simulation analysis and obtained by measurements in living mice.

Polymeric magnetic nanoparticles: a multitargeting approach for brain tumour therapy and imaging

The most challenging task in targeting the brain is trespassing the blood-brain barrier (BBB) which restricts the movement of about 98% small molecules. Targeting the central nervous system using magnetic nanoparticles may deliver the drug to the target site along with a contrast imaging property. The use of magnetic nanoparticles can become non-invasive drug targeting and a bio-imaging method for brain cancer. The strategy to apply polymeric nanoparticles as a carrier of magnetic iron oxide nanoparticles can be a promising tool as a multitherapeutic drug delivery approach involving delivery of chemotherapeutic drugs with a magnetic targeting approach, imaging, and hyperthermia. This review will highlight the existing difficulties/barriers in crossing the BBB, types of magnetic materials, polymeric carriers for functionalization of magnetic nanoparticles, and targeting strategies as therapeutic and imaging modalities. Utilization of polymeric magnetic nanoparticles as an efficient targeting platform for better drug delivery and imaging for brain cancer and future prospects are also discussed. Polymeric magnetic nanoparticles as a drug delivery and bio-imaging vehicle for brain cancer.

Model-based optimized steering and focusing of local magnetic particle concentrations for targeted drug delivery

Magnetic drug targeting (MDT) is an application in the field of targeted drug delivery in which magnetic (nano)particles act as drug carriers. The particles can be steered toward specific regions in the human body by adapting the currents of external (electro)magnets. Accurate models of particle movement and control algorithms for the electromagnet currents are two of the many requirements to ensure effective drug targeting. In this work, a control approach for the currents is presented, based on an underlying physical model that describes the dynamics of particles in a liquid in terms of their concentration in each point in space. Using this model, the control algorithm determines the currents generating the magnetic fields that maximize the particle concentration in spots of interest over a period of time. Such an approach is computationally only feasible thanks to our innovative combination of model order reduction with the method of direct multiple shooting. Simulation results of an in-vitro targeting setup demonstrated that a particle collection can be successfully guided toward the targeted spot with limited dispersion through a surrounding liquid. As now present and future particle behavior can be taken into account, and non-stationary surrounding liquids can be dealt with, a more precise and flexible targeting is achieved compared to existing MDT methods. This proves that the presented methodology can bring MDT closer to its clinical application. Moreover, the developed model is compatible with state-of-the-art imaging methods, paving the way for theranostic platforms that combine both therapy as well as diagnostics.

Regulation of oligonucleotide adsorption by a thermo and pH dual-responsive copolymer layer

Oligonucleotides hold great promise as therapeutic agents to specifically and selectively inhibit gene expression. In order to achieve better targeting efficiency and treatment efficacy, nanocarriers that are dual-responsive to both temperature and pH are more attractive and suitable due to the fact that certain malignancies can cause a slight increase of local temperature and a minor decrease in extracellular pH around the tumor site at the same time. Here, we systematically study oligonucleotide adsorption on the poly(ethyleneimine)-b-poly(N-isopropylacrylamide) (PEI-b-PNIPAm) copolymer layer grafted on a planar surface and nanoparticles with various radii, where the single effect of temperature or pH alone on oligonucleotide adsorption has been extensively investigated, but the combined effect of temperature and pH is less discussed. The theoretical results show that the surface density of the adsorbed oligonucleotides exhibits thermo and pH dual-responsive behavior, in which temperature and pH exhibit a combined effect on the loading capacity of the oligonucleotides. The underlying molecular mechanism of the dual-responsive behavior is revealed. Besides, the effect of important but coupled parameters in nanocarrier design such as polymer surface coverage and length, salt concentration as well as surface curvature (inverse nanoparticle radius) that may influence the dual-responsive behavior of oligonucleotide adsorption is further discussed, which is of great significance to direct the optimal design of PNIPAm/PEI-based nanocarriers to improve the transfection efficiency by achieving the maximal loading capacity of oligonucleotides at different temperatures and pH values.

Recent advances in iron oxide nanoparticles for brain cancer theranostics: from in vitro to clinical applications

Introduction: Today, the development of multifunctional nanoplatforms is more seriously considered in the field of cancer theranostics.Areas covered: In this respect, nanoparticles provide several advantages over the routine, conventional diagnostic methods, and treatments. Due to the expedient properties of iron oxide nanoparticles, such as being readily modified, great payload potential, intrinsic magnetic qualification, considerable biocompatibility, and overwhelming response to targeting strategies, these nanoparticles can be considered good candidates for application as diagnostic contrast agents and drug/gene delivery vehicles, while also being incorporated into hyperthermia-based approaches. Interestingly, these agents are detectable with routine imaging modalities such as magnetic resonance imaging.Expert opinion: Therefore, combining the traditional diagnostics and therapies with nanotechnological approaches may leave a positive impact on the survival rate of patients with cancer. This review summarizes the application of magnetic iron oxide nanoparticles in both in vitro and in vivo models of brain tumors.

Immobilization of alcohol dehydrogenase from Saccharomyces cerevisiae onto carboxymethyl dextran-coated magnetic nanoparticles: a novel route for biocatalyst improvement via epoxy activation

A novel method is described for the immobilization of alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae onto carboxymethyl dextran (CMD) coated magnetic nanoparticles (CMD-MNPs) activated with epoxy groups, using epichlorohydrin (EClH). EClH was used as an activating agent to bind ADH molecules on the surface of CMD-MNPs. Optimal immobilization conditions (activating agent concentration, temperature, rotation speed, medium pH, immobilization time and enzyme concentration) were set to obtain the highest expressed activity of the immobilized enzyme. ADH that was immobilized onto epoxy-activated CMD-MNPs (ADH-CMD-MNPs) maintained 90% of the expressed activity. Thermal stability of ADH-CMD-MNPS after 24 h at 20 °C and 40 °C yielded 79% and 80% of initial activity, respectively, while soluble enzyme activity was only 19% at 20 °C and the enzyme was non-active at 40 °C. Expressed activity of ADH-CMD-MNPs after 21 days of storage at 4 °C was 75%. Kinetic parameters (K_M, v_max) of soluble and immobilized ADH were determined, resulting in 125 mM and 1.2 µmol/min for soluble ADH, and in 73 mM and 4.7 µmol/min for immobilized ADH.

Targeted delivery of β-glucosidase-loaded magnetic nanoparticles: effect of external magnetic field duration and intensity

Aim: The effect of applied magnetic field duration and intensity on the delivery of β-glucosidase-loaded magnetic nanoparticles was evaluated. Materials & methods: The prepared β-glucosidase-loaded magnetic nanoparticles were targeted to subcutaneous tumors with an external magnetic field. Iron concentration and enzyme activity in tumor tissue were analyzed via electron spin resonance detection, Prussian blue staining and enzyme activity measurement. Results: The increase in magnetic nanoparticles quantity and enzyme activity in tumor tissue was not synchronous with the magnetic targeting duration. In addition, accumulation of magnetic nanoparticles and the increase in enzyme activity were not synchronous with the magnetic field intensity. Conclusion: The results suggested that appropriate magnetic field conditions should be considered for targeted delivery of bioactivity proteins based on magnetic nanoparticles.

Strategies for Improved Intra-arterial Treatments Targeting Brain Tumors: a Systematic Review

Conventional treatments for brain tumors relying on surgery, radiation, and systemic chemotherapy are often associated with high recurrence and poor prognosis. In recent decades, intra-arterial administration of anti-cancer drugs has been considered a suitable alternative drug delivery route to intravenous and oral administration. Intra-arterial administration is believed to offer increasing drug responses by primary and metastatic brain tumors, and to be associated with better median overall survival. By directly injecting therapeutic agents into carotid or vertebral artery, intra-arterial administration rapidly increases intra-tumoral drug concentration but lowers systemic exposure. However, unexpected vascular or neural toxicity has questioned the therapeutic safety of intra-arterial drug administration and limits its widespread clinical application. Therefore, improving targeting and accuracy of intra-arterial administration has become a major research focus. This systematic review categorizes strategies for optimizing intra-arterial administration into five categories: (1) transient blood-brain barrier (BBB)/blood-tumor barrier (BTB) disruption, (2) regional cerebral hypoperfusion for peritumoral hemodynamic changes, (3) superselective endovascular intervention, (4) high-resolution imaging techniques, and (5) others such as cell and gene therapy. We summarize and discuss both preclinical and clinical research, focusing on advantages and disadvantages of different treatment strategies for a variety of cerebral tumor types.

Beyond Oncological Hyperthermia: Physically Drivable Magnetic Nanobubbles as Novel Multipurpose Theranostic Carriers in the Central Nervous System

Magnetic Oxygen-Loaded Nanobubbles (MOLNBs), manufactured by adding Superparamagnetic Iron Oxide Nanoparticles (SPIONs) on the surface of polymeric nanobubbles, are investigated as theranostic carriers for delivering oxygen and chemotherapy to brain tumors. Physicochemical and cyto-toxicological properties and in vitro internalization by human brain microvascular endothelial cells as well as the motion of MOLNBs in a static magnetic field were investigated. MOLNBs are safe oxygen-loaded vectors able to overcome the brain membranes and drivable through the Central Nervous System (CNS) to deliver their cargoes to specific sites of interest. In addition, MOLNBs are monitorable either via Magnetic Resonance Imaging (MRI) or Ultrasound (US) sonography. MOLNBs can find application in targeting brain tumors since they can enhance conventional radiotherapy and deliver chemotherapy being driven by ad hoc tailored magnetic fields under MRI and/or US monitoring.

Breaking Barriers: Bioinspired Strategies for Targeted Neuronal Delivery to the Central Nervous System

Central nervous system (CNS) disorders encompass a vast spectrum of pathological conditions and represent a growing concern worldwide. Despite the high social and clinical interest in trying to solve these pathologies, there are many challenges to bridge in order to achieve an effective therapy. One of the main obstacles to advancements in this field that has hampered many of the therapeutic strategies proposed to date is the presence of the CNS barriers that restrict the access to the brain. However, adequate brain biodistribution and neuronal cells specific accumulation in the targeted site also represent major hurdles to the attainment of a successful CNS treatment. Over the last few years, nanotechnology has taken a step forward towards the development of therapeutics in neurologic diseases and different approaches have been developed to surpass these obstacles. The versatility of the designed nanocarriers in terms of physical and chemical properties, and the possibility to functionalize them with specific moieties, have resulted in improved neurotargeted delivery profiles. With the concomitant progress in biology research, many of these strategies have been inspired by nature and have taken advantage of physiological processes to achieve brain delivery. Here, the different nanosystems and targeting moieties used to achieve a neuronal delivery reported in the open literature are comprehensively reviewed and critically discussed, with emphasis on the most recent bioinspired advances in the field. Finally, we express our view on the paramount challenges in targeted neuronal delivery that need to be overcome for these promising therapeutics to move from the bench to the bedside.

Recent advancements in brain tumor targeting using magnetic nanoparticles

Transport of drugs through the blood-brain barrier to the brain and the toxic effects of drugs on the healthy cells can limit the effectiveness of chemotherapeutic agents. In recent years, magnetic nanoparticles (MNPs) have received much attention as targeted therapeutic and diagnostic systems due to their simplicity, ease of preparation and ability to tailor their properties such as their composition, size, surface morphology, etc. for biomedical applications. MNPs are utilized in drug delivery, radio therapeutics, hyperthermia treatment, gene therapy, biotherapeutics and diagnostic imaging. The present review will address the challenges in brain tumor targeting and discuss the application and recent developments in brain tumor targeting using MNPs.

Dual-Targeting Temozolomide Loaded in Folate-Conjugated Magnetic Triblock Copolymer Nanoparticles to Improve the Therapeutic Efficiency of Rat Brain Gliomas

In order to conduct an effective chemotherapy session as a treatment modality for glioblastoma tumors, a nanocarrier platform is required for the drug to cross the blood brain barrier (BBB) successfully and properly target glioma cells. Dual-targeting Temozolomide (TMZ) loaded triblock polymer coated magnetic nanoparticles (MNPs) were synthesized with a SPION core and by conjugating the surface with folic acid (FA), which were shown to effectively pass the BBB and target tumor cells. Two principal methods, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were employed for characterization of the synthesized nanoparticles. TMZ-loaded MNP-FA nanoparticles presented with a size of 58.61 nm, a zeta potential of -29.85 ± 0.47 mV, and a drug loading content of 6.85 ± 0.46%. Data gathered from inductively coupled plasma optical emission spectrometry (ICP-OES) and Prussian blue staining indicated effective dual-targeting, which subsequently led to an appreciably enhanced penetration through the BBB and accumulation of MNPs-FA in rat glioma cells. The anticancer effect of the dual-targeting MNPs-FA was also indicated by the increased survival time (>100%, p < 0.001) and decreased tumor volume (p < 0.001). In conclusion, the dual-targeting TMZ-loaded MNPs-FA are able to improve therapeutic efficiency toward brain gliomas in rats.

Nano-mediated delivery of double-stranded RNA for gene therapy of glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most common type of malignant gliomas, characterized by genetic instability, intratumoral histopathological variability and unpredictable clinical behavior. Disappointing results in the treatment of gliomas with surgery, radiation and chemotherapy have fueled a search for new therapeutic targets and treatment modalities. Here we report new approach towards RNA interference therapy of glioblastoma multiforme based on the magnetic nanoparticles delivery of the double-stranded RNA (dsRNA) with homological sequences to mRNA of tenascin-C (TN-C), named ATN-RNA. The obtained nanocomposite consisted of polyethyleneimine (PEI) coated magnetic nanoparticles conjugated to the dsRNA show high efficiency in ATN-RNA delivery, resulting not only in significant TN-C expression level suppressesion, but also impairing the tumor cells migration. Moreover, synthesized nanomaterials show high contrast properties in magnetic resonance imaging (MRI) and low cytotoxicity combining with lack of induction of interferon response. We believe that the present work is a successful combination of effective, functional, non-immunostimulatory dsRNA delivery system based on magnetic nanoparticles with high potential for further application in GBM therapy.

Granzyme B Functionalized Nanoparticles Targeting Membrane Hsp70-Positive Tumors for Multimodal Cancer Theranostics

Functionalized superparamagnetic iron oxide nanoparticles (SPIONs) have emerged as potential clinical tools for cancer theranostics. Membrane-bound 70 kDa heat shock protein (mHsp70) is ubiquitously expressed on the cell membrane of various tumor types but not normal cells and therefore provides a tumor-specific target. The serine protease granzyme B (GrB) that is produced as an effector molecule by activated T and NK cells has been shown to specifically target mHsp70 on tumor cells. Following binding to Hsp70, GrB is rapidly internalized into tumor cells. Herein, it is demonstrated that GrB functionalized SPIONs act as a contrast enhancement agent for magnetic resonance imaging and induce specific tumor cell apoptosis. Combinatorial regimens employing stereotactic radiotherapy and/or magnetic targeting are found to further enhance the therapeutic efficacy of GrB-SPIONs in different tumor mouse models.

Fe3O4-solamargine induces apoptosis and inhibits metastasis of pancreatic cancer cells

Fe3O4-magnetic liposome (MLP) can deliver drugs to target tissues and can increase drug efficacy. The present study aimed to investigate the effects of solamargine (SM) and Fe3O4-SM in pancreatic cancer (PC). Cell viability was detected using a Cell Counting kit‑8 assay. Apoptosis and cell cycle progression was tested using a flow cytometry assay. A scratch assay was used to examine cell metastasis. Quantitative polymerase chain reaction, western blot analysis or immunohistochemical analysis were performed to determine the expression of target factors. Magnetic resonance imagining (MRI) and terminal deoxynucleotidyl-transferase-mediated dUTP nick end labelling were conducted to detect tumor growth and apoptosis in vivo, respectively. It was demonstrated that Fe3O4-SM inhibited cancer cell growth via a slow release of SM over an extended period of time. SM was revealed to induce apoptosis and cell cycle arrest. Furthermore, SM decreased the expression of X-linked inhibitor of apoptosis, Survivin, Ki‑67, proliferating cell nuclear antigen and cyclin D1, but increased the activity of caspase-3. It was also observed that SM inhibited tumor cell metastasis by modulating the expression of matrix metalloproteinase (MMP)-2 and TIMP metallopeptidase inhibitor-2. Furthermore, the phosphorylation of protein kinase B and mechanistic target of rapamycin was suppressed by SM. Notably, the effect of SM was enhanced by Fe3O4-SM. The malignant growth of PC was decreased by SM in vivo. Furthermore, the expression of Ki‑67 was decreased by SM and Fe3O4-SM. Additionally, cell apoptosis was increased in the Fe3O4-SM group, compared with the SM group. The present study illustrated the antitumor effect and action mec-hanism produced by SM. Additionally, it was demonstrated that Fe3O4-SM was more effective than SM in protecting against PC.

Functionalized Superparamagnetic Iron Oxide Nanoparticles (SPIONs) as Platform for the Targeted Multimodal Tumor Therapy

Standard cancer treatments involve surgery, radiotherapy, chemotherapy, and immunotherapy. In clinical practice, the respective drugs are applied orally or intravenously leading to their systemic circulation in the whole organism. For chemotherapeutics or immune modulatory agents, severe side effects such as immune depression or autoimmunity can occur. At the same time the intratumoral drug doses are often too low for effective cancer therapy. Since monotherapies frequently cannot cure cancer, due to their synergistic effects multimodal therapy concepts are applied to enhance treatment efficacy. The targeted delivery of drugs to the tumor by employment of functionalized nanoparticles might be a promising solution to overcome these challenges. For multimodal therapy concepts and individualized patient care nanoparticle platforms can be functionalized with compounds from various therapeutic classes (e.g. radiosensitizers, phototoxic drugs, chemotherapeutics, immune modulators). Superparamagnetic iron oxide nanoparticles (SPIONs) as drug transporters can add further functionalities, such as guidance or heating by external magnetic fields (Magnetic Drug Targeting or Magnetic Hyperthermia), and imaging-controlled therapy (Magnetic Resonance Imaging).

Development of a magnetic nano-graphene oxide carrier for improved glioma-targeted drug delivery and imaging: In vitro and in vivo evaluations

To overcome the obstacles inflicted by the BBB in Glioblastoma multiforme (GBM) we investigated the use of Multifunctional nanoparticles that designed with a Nano-graphene oxide (NGO) sheet functionalized with magnetic poly (lactic-co-glycolic acid) (PLGA) and was used for glioma targeting delivery of radiosensitizing 5-iodo-2-deoxyuridine (IUdR). In vitro biocompatibility of nanocomposite has been studied by the MTT assay. In vivo efficacy of magnetic targeting on the amount and selectivity of magnetic nanoparticles accumulation in glioma-bearing rats under an external magnetic field (EMF) density of 0.5 T was easily monitored with MRI. IUdR-loaded magnetic NGO/PLGA with a diameter of 71.8 nm, a zeta potential of -33.07 ± 0.07 mV, and a drug loading content of 3.04 ± 0.46% presented superior superparamagnetic properties with a saturation magnetization (Ms) of 15.98 emu/g. Furthermore, Prussian blue staining showed effective magnetic targeting, leading to remarkably improved tumor inhibitory efficiency of IUdR. The tumor volume of rats after treatment with IUdR/NGO/SPION/PLGA + MF was decreased significantly compared to the rats treated with buffer saline, IUdR and SPION/IUdR/NGO/PLGA. Most importantly, our data demonstrate that IUdR/NGO/SPION/PLGA at the present magnetic field prolongs the median survival time of animals bearing gliomas (38 days, p < 0.01). Nanoparticles also had high thermal sensitivities under the alternating magnetic field. In conclusion, we developed magnetic IUdR/NGO/PLGA, which not only achieved to high accumulation at the targeted tumor site by magnetic targeting but also indicated significantly enhanced therapeutic efficiency and toxicity for glioma both in vitro and in vivo. This innovation increases the possibility of improving clinical efficiency of IUdR as a radiosensitizer, or lowering the total drug dose to decrease systemic toxicity.

In Vitro Carcinoma Treatment Using Magnetic Nanocarriers under Ultrasound and Magnetic Fields

Nowadays, tumor hypoxia has become a more predominant problem for diagnosis as well as treatment of cancer due to difficulties in delivering chemotherapeutic drugs and their carriers to these regions with reduced vasculature and oxygen supply. In such cases, external physical stimulus-mediated drug delivery, such as ultrasound and magnetic fields, would be effective. In this work, the effect of simultaneous exposure of low-intensity pulsed ultrasound and static magnetic field on colon (HCT116) and hepatocellular (HepG2) carcinoma cell inhibition was assessed in vitro. The treatment, in the presence of anticancer drug, with and without magnetic carrier, significantly increased the reactive oxygen species production and hyperpolarized the cancer cells. As a result, a significant increase in cell inhibition, up to 86%, was observed compared to 50% inhibition with bare anticancer drug. The treatment appears to have relatively more effect on HepG2 cells during the initial 24 h than on HCT116 cells. The proposed treatment was also found to reduce cancer cell necrosis and did not show any inhibitory effect on healthy cells (MC3T3). Our in vitro results suggest that this approach has strong application potential to treat cancer at lower drug dosage to achieve similar inhibition and can reduce health risks associated with drugs.

A Novel Magnetic Actuation Scheme to Disaggregate Nanoparticles and Enhance Passage across the Blood-Brain Barrier

The blood–brain barrier (BBB) hinders drug delivery to the brain. Despite various efforts to develop preprogramed actuation schemes for magnetic drug delivery, the unmodeled aggregation phenomenon limits drug delivery performance. This paper proposes a novel scheme with an aggregation model for a feed-forward magnetic actuation design. A simulation platform for aggregated particle delivery is developed and an actuation scheme is proposed to deliver aggregated magnetic nanoparticles (MNPs) using a discontinuous asymmetrical magnetic actuation. The experimental results with a Y-shaped channel indicated the success of the proposed scheme in steering and disaggregation. The delivery performance of the developed scheme was examined using a realistic, three-dimensional (3D) vessel simulation. Furthermore, the proposed scheme enhanced the transport and uptake of MNPs across the BBB in mice. The scheme presented here facilitates the passage of particles across the BBB to the brain using an electromagnetic actuation scheme.

Analysis of Hypericin-Mediated Effects and Implications for Targeted Photodynamic Therapy

The phototoxic effect of hypericin can be utilized for Photodynamic Therapy (PDT) of cancer. After intravenous application and systemic distribution of the drug in the patient's body, the tumor site is exposed to light. Subsequently, toxic reactive oxygen species (ROS) are generated, inducing tumor cell death. To prevent unwanted activation of the drug in other regions of the body, patients have to avoid light during and after the treatment cycles, consequently impairing quality of life. Here, we characterize toxicity and hypericin-mediated effects on cancer cells in vitro and confirm that its effect clearly depends on concentration and illumination time. To reduce side effects and to increase therapy success, selective accumulation of hypericin in the tumor region is a promising solution. Loading hypericin on superparamagnetic iron oxide nanoparticles (SPIONs) and guiding them to the desired place using an external magnetic field might accomplish this task (referred to as Magnetic Drug Targeting (MDT)). Thus, using a double targeting strategy, namely magnetic accumulation and laser induced photoactivation, might improve treatment effectivity as well as specificity and reduce toxic side effects in future clinical applications.

Earthicle: The Design of a Conceptually New Type of Particle

The conception and the steps made in the design of a conceptually new type of composite particle, so-called "earthicle", are being described. This particle is meant to roughly mimic the layered structure of the Earth, having zerovalent iron core, silicate mantle, and a thin carbonaceous crust resembling the biosphere and its geological remnants. Particles are made in a stable colloidal form in an aqueous medium, involving chemical precipitation and pyrolysis of citric acid in the solution. The effects of various synthesis parameters were studied, including borohydride and oleate concentrations, APTES/TEOS molar ratio, chemical nature of the carbon precursors, and others. XRD analysis confirmed the predominantly zerovalent iron composition of the core, amorphous silica and crystalline iron silicate/silicide composition of the mesolayer, and the carbonaceous, amorphous graphitic composition of the surface coating. The atomically thin carbon shell was also detected as a distinct shoulder on the broad n-π* absorption resonance and the peak at ∼300 nm, a signature of sp² hybridized electronic orbitals and the result of the interband π-π* transition characteristic of graphitic structures. The irregularity of the shape of generally round Fe⁰ particles has caused the uniformity of the silica shell to be directly proportional to the particle size. The size of the earthicles ranged from 60 to 500 nm depending on the ionic concentration of the precursors and additives. Silica layer effectively prevented the aggregation of the iron core and increased the biocompatibility of the particles. The point of zero charge first increased from the acidic to the neutral range after coating Fe⁰ core with the APTES-functionalized, aminated silica shell and then restored its low value after depositing the carboxylated carbonic crust in a charge-reversal process designed to facilitate the formation of core-multishell structures. Tested on K7M2 osteosarcoma cell line and primary kidney and lung fibroblasts, cytotoxicity was cell-line dependent; however, the trend assessed in both planar and 3D cell culture with respect to the three types of particles, Fe⁰, Fe/SiO₂, and Fe/SiO₂/C, was general and independent of the cell line. Thus, the pronounced toxicity of Fe⁰ alone became neutralized after the silica layer was coated around Fe⁰. The further addition of the carbonic layer reduced the viability as compared to Fe/SiO₂, albeit in a statistically significant manner only for K7M2 cell line when compared against the untreated control. Cell response also varied depending on the formulation: while some formulations exhibited lethal effects on kidney fibroblasts, were harmless to lung fibroblasts, and boosted the proliferation of K7M2 osteosarcoma cells, other formulations exhibited the opposite behavior despite being similar in terms of their core/double-shell structure. Compared across three different cancerous cell lines, K7M2 osteosarcoma and U87 and E297 glioblastoma, a similar cell-line dependency in response was observed, yet the viability reduction was consistent for all Fe/SiO₂/C particles, ranging from 80% to 85% of the untreated control. Carbon surface layer, albeit of graphitic structural nature, was of a markedly more viable character than that of nanosized graphene oxide. The viability of lung fibroblasts incubated with Fe/SiO₂/C particles was reduced in the presence of the alternating magnetic field of 312.75 A/m and 1 MHz, while the viability reduction caused by Fe/SiO₂/C particles in kidney fibroblasts and K7M2 cells was converted from statistically insignificant to significant, suggesting that the composite particles could be used for hyperthermia treatments, although their properties should be optimized for a more intense effect. A single-cell immunofluorescent analysis of the interaction of primary kidney fibroblasts and K7M2 osteosarcoma cells with Fe/SiO₂/C particles demonstrated that the cell uptake and perinuclear localization may be responsible for the necrotic effects. This analysis also showed that composite Fe/SiO₂/C particles may have the ability to cause the rupture of the cancer cell nucleus while having a harmless effect on the primary cells. Such a promising and selective anticancer activity will be investigated in more detail in future studies.

Real-time monitoring of magnetic drug targeting using fibered confocal fluorescence microscopy

Magnetic drug targeting has been proposed as means of concentrating therapeutic agents at a target site and the success of this approach has been demonstrated in a number of studies. However, the behavior of magnetic carriers in blood vessels and tumor microcirculation still remains unclear. In this work, we utilized polymeric magnetic nanocapsules (m-NCs) for magnetic targeting in tumors and dynamically visualized them within blood vessels and tumor tissues before, during and after magnetic field exposure using fibered confocal fluorescence microscopy (FCFM). Our results suggested that the distribution of m-NCs within tumor vasculature changed dramatically, but in a reversible way, upon application and removal of a magnetic field. The m-NCs were concentrated and stayed as clusters near a blood vessel wall when tumors were exposed to a magnetic field but without rupturing the blood vessel. The obtained FCFM images provided in vivo in situ microvascular observations of m-NCs upon magnetic targeting with high spatial resolution but minimally invasive surgical procedures. This proof-of-concept descriptive study in mice is envisaged to track and quantify nanoparticles in vivo in a non-invasive manner at microscopic resolution.

Magnetic Drug Targeting: Preclinical in Vivo Studies, Mathematical Modeling, and Extrapolation to Humans

A sound theoretical rationale for the design of a magnetic nanocarrier capable of magnetic capture in vivo after intravenous administration could help elucidate the parameters necessary for in vivo magnetic tumor targeting. In this work, we utilized our long-circulating polymeric magnetic nanocarriers, encapsulating increasing amounts of superparamagnetic iron oxide nanoparticles (SPIONs) in a biocompatible oil carrier, to study the effects of SPION loading and of applied magnetic field strength on magnetic tumor targeting in CT26 tumor-bearing mice. Under controlled conditions, the in vivo magnetic targeting was quantified and found to be directly proportional to SPION loading and magnetic field strength. Highest SPION loading, however, resulted in a reduced blood circulation time and a plateauing of the magnetic targeting. Mathematical modeling was undertaken to compute the in vivo magnetic, viscoelastic, convective, and diffusive forces acting on the nanocapsules (NCs) in accordance with the Nacev-Shapiro construct, and this was then used to extrapolate to the expected behavior in humans. The model predicted that in the latter case, the NCs and magnetic forces applied here would have been sufficient to achieve successful targeting in humans. Lastly, an in vivo murine tumor growth delay study was performed using docetaxel (DTX)-encapsulated NCs. Magnetic targeting was found to offer enhanced therapeutic efficacy and improve mice survival compared to passive targeting at drug doses of ca. 5-8 mg of DTX/kg. This is, to our knowledge, the first study that truly bridges the gap between preclinical experiments and clinical translation in the field of magnetic drug targeting.

Monoclonal antibody-conjugated superparamagnetic iron oxide nanoparticles for imaging of epidermal growth factor receptor-targeted cells and gliomas

The objective of this study was to successfully synthesize epidermal growth factor receptor monoclonal antibody-conjugated superparamagnetic iron oxide nanoparticles (EGFRmAb-SPIONs) and explore their biocompatibility and potential applications as a targeted magnetic resonance imaging (MRI) contrast agent for the EGFR-specific detection of brain glioma in vivo. After conjugation of EGFRmAb with SPIONs, the magnetic characteristics of EGFRmAb-SPIONs were investigated. Thereafter, the targeting abilities of EGFRmAb-SPIONs with MRI were qualitatively and quantitatively assessed in EGFR-positive C6 glioma cells in vitro and in a Wistar rat model bearing C6 glioma in vivo. Furthermore, the preliminary biocompatibility and toxicity of EGFRmAb-SPIONs were evaluated in normal rats through hematology assays and histopathologic analyses. Statistical analysis was performed using one-way analysis of variance and Student t-test, with a significance level of p < .05. From the results of EGFRmAb-SPION characterizations, the average particle size was 10.21 nm and the hydrodynamic diameter was 161.5 ± 2.12 nm. The saturation magnetization was 55 emu/g·Fe, and T2 relaxivity was 92.73 s-1mM-1 in distilled water. The preferential accumulation of the EGFRmAb-SPIONs within glioma and subsequent MRI contrast enhancement were demonstrated both in vitro in C6 cells and in vivo in rats bearing C6 glioma. After intravenous administration of EGFRmAb-SPIONs, T2-weighted MRI of the rat model with brain glioma exhibited an apparent hypointense region within glioma from 2 to 48 hours. The maximal image contrast was reached at 24 hours, where the signal intensity decreased and the R2 value increased by 30% compared to baseline. However, T2-weighted imaging of the rat model administered with SPIONs showed no visible signal changes within the tumor over the same time period. Moreover, no evident toxicities in vitro and in vivo with EGFRmAb-SPIONs were clearly identified based on the laboratory examinations. EGFRmAb-SPIONs could potentially be employed as a targeted contrast agent in the molecule-specific diagnosis of brain glioma in MRI.

β-Cyclodextrin based magnetic nanoconjugates for targeted drug delivery in cancer therapy

β-Cyclodextrin based magnetic nanoconjugates for targeted drug delivery.

Superparamagnetic yolk–shell porous nanospheres of iron oxide@magnesium silicate: synthesis and application in high-performance anticancer drug delivery

The as-prepared yolk–shell porous nanospheres of SPIO@MS exhibit a high drug loading capacity, and a sustained and pH-responsive drug release behaviour.

Triple-Modal Imaging of Magnetically-Targeted Nanocapsules in Solid Tumours In Vivo

Triple-modal imaging magnetic nanocapsules, encapsulating hydrophobic superparamagnetic iron oxide nanoparticles, are formulated and used to magnetically target solid tumours after intravenous administration in tumour-bearing mice. The engineered magnetic polymeric nanocapsules m-NCs are ~200 nm in size with negative Zeta potential and shown to be spherical in shape. The loading efficiency of superparamagnetic iron oxide nanoparticles in the m-NC was ~100%. Up to ~3- and ~2.2-fold increase in tumour uptake at 1 and 24 h was achieved, when a static magnetic field was applied to the tumour for 1 hour. m-NCs, with multiple imaging probes (e.g. indocyanine green, superparamagnetic iron oxide nanoparticles and indium-111), were capable of triple-modal imaging (fluorescence/magnetic resonance/nuclear imaging) in vivo. Using triple-modal imaging is to overcome the intrinsic limitations of single modality imaging and provides complementary information on the spatial distribution of the nanocarrier within the tumour. The significant findings of this study could open up new research perspectives in using novel magnetically-responsive nanomaterials in magnetic-drug targeting combined with multi-modal imaging.

Nanotechnology in neurology: Genesis, current status, and future prospects

Nanotechnology is a promising, novel field of technological development. There is great potential in research and clinical applications for neurological diseases. Here we chronicle the inception of nanotechnology, discuss its integration with neurology, and highlight the challenges in current application. Some of the problems involving practical use of neuronanotechnology are direct biological toxicity, visualization of the nanodevice, and the short life expectancy of nanomachinery. Neuron cell therapy is an upcoming field for the treatment of challenging problems in neurology. Peptide nanofibers based on amphiphilic molecules have been developed that can autoregulate their structure depending on the conditions of the surrounding milieu. Such frameworks are promising for serving as drug delivery systems or communication bridges between damaged neurons. For common disabling diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS), recent developments have seen revolutionary nanotech-based novelties, which are discussed here in detail. Bioimaging integrated with nanoneuromedicine has opened up new doors for cancer and infection therapeutics.

Magnetic Nanoparticles Cross the Blood-Brain Barrier: When Physics Rises to a Challenge

The blood-brain barrier is a physical and physiological barrier that protects the brain from toxic substances within the bloodstream and helps maintain brain homeostasis. It also represents the main obstacle in the treatment of many diseases of the central nervous system. Among the different approaches employed to overcome this barrier, the use of nanoparticles as a tool to enhance delivery of therapeutic molecules to the brain is particularly promising. There is special interest in the use of magnetic nanoparticles, as their physical characteristics endow them with additional potentially useful properties. Following systemic administration, a magnetic field applied externally can mediate the capacity of magnetic nanoparticles to permeate the blood-brain barrier. Meanwhile, thermal energy released by magnetic nanoparticles under the influence of radiofrequency radiation can modulate blood-brain barrier integrity, increasing its permeability. In this review, we present the strategies that use magnetic nanoparticles, specifically iron oxide nanoparticles, to enhance drug delivery to the brain.

Pharmacokinetics, pharmacodynamics and toxicology of theranostic nanoparticles

Nanoparticles (NPs) are considered a promising tool in both diagnosis and therapeutics. Theranostic NPs possess the combined properties of targeted imaging and drug delivery within a single entity. While the categorization of theranostic NPs is based on their structure and composition, the pharmacokinetics of NPs are significantly influenced by the physicochemical properties of theranostic NPs as well as the routes of administration. Consequently, altered pharmacokinetics modify the pharmacodynamic efficacy and toxicity of NPs. Although theranostic NPs hold great promise in nanomedicine and biomedical applications, a lack of understanding persists on the mechanisms of the biodistribution and adverse effects of NPs. To better understand the diagnostic and therapeutic functions of NPs, this review discusses the factors that influence the pharmacokinetics, pharmacodynamics and toxicology of theranostic NPs, along with several strategies for developing novel diagnostic and therapeutic modalities.

Specific detection of CD133-positive tumor cells with iron oxide nanoparticles labeling using noninvasive molecular magnetic resonance imaging

Background

The use of ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles to visualize cells has been applied clinically, showing the potential for monitoring cells in vivo with magnetic resonance imaging (MRI). USPIO conjugated with anti-CD133 antibodies (USPIO-CD133 Ab) that recognize the CD133 molecule, a cancer stem cell marker in a variety of cancers, was studied as a novel and potent agent for MRI contrast enhancement of tumor cells.

Materials and methods

Anti-CD133 antibodies were used to conjugate with USPIO via interaction of streptavidin and biotin for in vivo labeling of CD133-positive cells in xenografted tumors and N-ethyl-N-nitrosourea (ENU)-induced brain tumors. The specific binding of USPIO-CD133 Ab to CD133-positive tumor cells was subsequently detected by Prussian blue staining and MRI with T2-weighted, gradient echo and multiple echo recombined gradient echo images. In addition, the cellular toxicity of USPIO-CD133 Ab was determined by analyzing cell proliferation, apoptosis, and reactive oxygen species production.

Results

USPIO-CD133 Ab specifically recognizes in vitro and labels CD133-positive cells, as validated using Prussian blue staining and MRI. The assays of cell proliferation, apoptosis, and reactive oxygen species production showed no significant differences in tumor cells with or without labeling of USPIO-CD133 Ab. In vivo imaging of CD133-positive cells was demonstrated by intravenous injection of USPIO-CD133 Ab in mice with HT29 xenografted tumors. The MRI of HT29 xenografts showed several clusters of hypotensive regions that correlated with CD133 expression and Prussian blue staining for iron. In rat, brain tumors induced by transplacental ENU mutagenesis, several clusters of hypointensive zones were observed in CD133-expressing brain tumors by MRI and intravenously administered USPIO-CD133 Ab.

Conclusion

Combination of USPIO-CD133 Ab and MRI is valuable in recognizing CD133-expressing tumor cells in vitro, extracellularly labeling for cell tracking and detecting CD133-expressing tumors in xenografted tumors as well as ENU-induced rat brain tumors.

Drug delivery strategies to enhance the permeability of the blood-brain barrier for treatment of glioma

Gliomas are amongst the most insidious and destructive types of brain cancer and are associated with a poor prognosis, frequent recurrences, and extremely high lethality despite combination treatment of surgery, radiotherapy, and chemotherapy. The existence of the blood–brain barrier (BBB) restricts the delivery of therapeutic molecules into the brain and offers the clinical efficacy of many pharmaceuticals that have been demonstrated to be effective for other kinds of tumors. This challenge emphasizes the need to be able to deliver drugs effectively across the BBB to reach the brain parenchyma. Enhancement of the permeability of the BBB and being able to transport drugs across it has been shown to be a promising strategy to improve drug absorption and treatment efficacy. This review highlights the innovative technologies that have been introduced to enhance the permeability of the BBB and to obtain an optimal distribution and concentration of drugs in the brain to treat gliomas, such as nanotechniques, hyperthermia techniques, receptor-mediated transport, cell-penetrating peptides, and cell-mediated delivery.