Magnetically modulated nanosystems: a unique drug-delivery platform

Fabrication of Superparamagnetic Bimetallic Magnesium Nanoferrite Using Green Polyol: Characterization and Anticancer Analysis in Vitro on Lung Cancer Cell Line A549

Magnetic bimetallic nanoparticles find many industrial and clinical applications in the field of water treatment, antibacterial and anticancer activities. Therefore, the current article reports green synthesis using oleo-polyol as a surface modifier and synthesis agent for bimetallic magnetic magnesium ferrite nanoparticles. The role of hydroxyl functionality of castor oil (a natural polyol) on the enhancement of structural, morphological, magnetic, and particle size properties has also been discussed. These properties were characterized using FTIR, XRD spectroscopy, SEM, AFM, and TEM microscopy, Brunauer-Emmett-Teller (BET), and vibrating sample magnetometer (VSM) techniques. The effect of calcination temperatures (600-900 °C) on particle size (23-40 nm to 500-600 nm), crystallite sizes (73.15-292.67 nm), and saturation magnetization (20.87, 23.07, 32.39, and 33.13 emu g^-1) was analyzed. The influence of calcined temperatures on the anticancer activity of these nanoparticles has also been investigated in vitro using lung cancer cells (A549). Their biocompatibility, cytotoxicity, flow cytometry, and statistical analysis against lung cancer cells (A549) have been discussed. The green synthesis of magnesium nanoferrite particles using natural polyol and their application as anticancer agents against lung cancer cells (A549) have not been reported previously. They have exhibited far superior IC₅₀ values and anticancer activity as compared to other reported metal oxides and magnesium oxide nanoparticles.

Recent development of gene therapy for pancreatic cancer using non-viral nanovectors

Pancreatic cancer (PC), characterized by its dense desmoplastic stroma and hypovascularity, is one of the most lethal cancers with a poor prognosis in the world. Traditional treatments such as chemotherapy, radiotherapy, and targeted therapy show little benefit in the survival rate in patients with advanced PC due to the poor penetration and resistance of drugs, low radiosensitivity, or severe side effects. Gene therapy can modify the morbific and drug-resistant genes as well as insert the tumor-suppressing genes, which has been shown to have great potential in PC treatment. The development of safe non-viral vectors for the highly efficient delivery of nucleic acids is essential for effective gene therapy, and has been attracting much attention. In this review, we first summarized the PC-promoting genes and gene therapies using plasmid DNA, mRNA, miRNA/siRNA-based RNA interference technology, and genome editing technology. Second, the commonly used non-viral nanovector and theranostic gene delivery nanosystem, especially the tumor microenvironment-sensitive delivery nanosystem and the cell/tumor-penetrating delivery nanosystem, were introduced. Third, a combination of non-viral nanovector-based gene therapy and other therapies, such as immunotherapy, chemotherapy, photothermal therapy (PTT), and photodynamic therapy (PDT), for PDAC treatment was discussed. Finally, a number of clinical trials have demonstrated the proof-of-principle that gene therapy or the combination of gene therapy and chemotherapy using non-viral vectors can inhibit the progression of PC. Although most of the non-viral vector-based gene therapies and their combination therapy are still under preclinical research, the development of genetics, molecular biology, and novel vectors would promote the clinical transformation of gene therapy.

An in-depth analysis of novel combinatorial drug therapy via nanocarriers against HIV/AIDS infection and their clinical perspectives: a systematic review

Introduction: Conventional antiretroviral therapy against HIV infections is threatening to become outdated due to the low chemical, physical, biological, and pharmacokinetic characteristics of therapeutic molecules, followed by the high chance of emergence of drug resistance. Considering the co-encapsulation of multi-infection agents in a single nanocarrier is emerging to offer various benefits such as synergistic action, improved therapeutic efficacy, reduced drug resistance development, patient compliance, and economical therapy.Areas covered: A systematic review of nano-based combinatorial drug therapy was performed using various databases including Scopus, PubMed, Google Scholar, and Science Direct between 2000 and 2020. The search set was screened as per the inclusion and exclusion criteria, followed by 46 scientific articles and seven clinical studies selected for in-depth analysis.Expert opinion: There has been an immense effort to analyze the mechanism of HIV infection to develop a promising therapeutic approach, although the aim of complete prevention has not been succeeded yet. The key finding is to overcome the challenges associated with conventional therapy by the combinatorial drug in a single nanoformulation, which holds great potential for impact in the management of HIV infection.

Magnetically responsive polycaprolactone nanocarriers for application in the biomedical field: magnetic hyperthermia, magnetic resonance imaging, and magnetic drug delivery

There are huge demands on multifunctional nanocarriers to be used in nanomedicine. Herein, we present a simple and efficient method for the preparation of multifunctional magnetically responsive polymeric-based nanocarriers optimized for biomedical applications. The hybrid delivery system is composed of drug-loaded polymer nanoparticles (poly(caprolactone), PCL) coated with a multilayer shell of polyglutamic acid (PGA) and superparamagnetic iron oxide nanoparticles (SPIONs), which are known as bio-acceptable components. The PCL nanocarriers with a model anticancer drug (Paclitaxel, PTX) were formed by the spontaneous emulsification solvent evaporation (SESE) method, while the magnetically responsive multilayer shell was formed via the layer-by-layer (LbL) method. As a result, we obtained magnetically responsive polycaprolactone nanocarriers (MN-PCL NCs) with an average size of about 120 nm. Using the 9.4 T preclinical magnetic resonance imaging (MRI) scanner we confirmed, that obtained MN-PCL NCs can be successfully used as a MRI-detectable drug delivery system. The magnetic hyperthermia effect of the MN-PCL NCs was demonstrated by applying a 25 mT radio-frequency (f = 429 kHz) alternating magnetic field. We found a Specific Absorption Rate (SAR) of 55 W g-1. The conducted research fulfills the first step of investigation for biomedical application, which is mandatory for the planning of any in vitro and in vivo studies.

In vivo effect of magnetic microspheres loaded with E2-a in the treatment of alveolar echinococcosis

The alveolar echinococcosis of human is a severe helminthic disease caused by the larva of Echinococcus multilocularis tapeworms. Novel compounds or therapy strategies for the treatment of alveolar echinococcosis are urgently needed due to the limitation of the widely used albendazole. Magnetic microspheres as drug carriers in magnetically targeted therapy of tumor have gained growing interests advantaged by delivering the drug to the aimed site, achieving localized therapeutic effect effectively under the influence of an external magnetic field. In this study, we formulated magnetic microspheres loaded with E2-a (PLGA-Fe-E2-a) and identified the activity in E. multilocularis-infected mice which infected with 3,000 protoscoleces intraperitoneally. Compared with the untreated control, with the help of a magnet, there was a significant reduction in parasite burden with PLGA-Fe-E2-a treatment and similar reduction observed with albendazole. PLGA-Fe-E2-a treatment group also showed a significant increase in the IFN-γ level and impaired morphological and ultrastructural alterations. Most importantly, one-third concentrations of E2-a from PLGA-Fe-E2 based on the release profile of E2-a was equally effective in inhibiting metacestode growth as E2-a treated group, supporting efficacy and bioavailability of a drug. It will be an alternative treatment for alveolar echinococcosis using magnetic microspheres as drug carriers.

Magnetic Materials and Systems: Domain Structure Visualization and Other Characterization Techniques for the Application in the Materials Science and Biomedicine

Magnetic structures have attracted a great interest due to their multiple applications, from physics to biomedicine. Several techniques are currently employed to investigate magnetic characteristics and other physicochemical properties of magnetic structures. The major objective of this review is to summarize the current knowledge on the usage, advances, advantages, and disadvantages of a large number of techniques that are currently available to characterize magnetic systems. The present review, aiming at helping in the choice of the most suitable method as appropriate, is divided into three sections dedicated to characterization techniques. Firstly, the magnetism and magnetization (hysteresis) techniques are introduced. Secondly, the visualization methods of the domain structures by means of different probes are illustrated. Lastly, the characterization of magnetic nanosystems in view of possible biomedical applications is discussed, including the exploitation of magnetism in imaging for cell tracking/visualization of pathological alterations in living systems (mainly by magnetic resonance imaging, MRI).

Recent advances in musculoskeletal local drug delivery

Musculoskeletal disorders are a significant burden on the global economy and public health. Advanced drug delivery plays a key role in the musculoskeletal field and holds the promise of enhancing the repair of degenerated and injured musculoskeletal tissues. Ideally, drug delivery should have the ability to directly deliver therapeutic agents to the diseased/injured sites with a desirable drug level over a period of time. Here, we present a mini-review of the current state-of-the-art research associated with local drug delivery and its use for the treatment of musculoskeletal disorders. First, an overview of drug delivery strategies, with a focus on issues related to musculoskeletal pathology, potential therapeutic strategies, conventional and non-conventional drugs, and various delivery systems, is introduced. Then, we highlight recent advances in the emerging fields of musculoskeletal local drug delivery, involving therapeutic drugs (e.g., genes, small molecule therapeutics, and stem cells), novel delivery vehicles (e.g., 3D printing and tissue engineering techniques), and innovative delivery approaches (e.g., multi-drug delivery and smart stimuli-responsive delivery). The review concludes with future perspectives and associated challenges for developing local drug delivery for musculoskeletal applications. STATEMENT OF SIGNIFICANCE: Three important aspects are highlighted in this manuscript: 1) The advanced musculoskeletal drug delivery is introduced from the aspects ranging from musculoskeletal disorders, potential therapeutic solutions, and various drug delivery systems. 2) The recent advances in the emerging fields of musculoskeletal local drug delivery, involving therapeutic drugs (e.g., genes, small molecule therapeutics, and stem cells), novel delivery vehicles (e.g., 3D printing and tissue engineering technique), and innovative delivery approaches (e.g., multi-drug delivery and smart stimuli-responsive delivery), are highlighted. 3) The challenges and perspectives of future research directions in the development of musculoskeletal local drug delivery are presented.

A perspective on magnetic core-shell carriers for responsive and targeted drug delivery systems

Magnetic core-shell nanocarriers have been attracting growing interest owing to their physicochemical and structural properties. The main principles of magnetic nanoparticles (MNPs) are localized treatment and stability under the effect of external magnetic fields. Furthermore, these MNPs can be coated or functionalized to gain a responsive property to a specific trigger, such as pH, heat, or even enzymes. Current investigations have been focused on the employment of this concept in cancer therapies. The evaluation of magnetic core-shell materials includes their magnetization properties, toxicity, and efficacy in drug uptake and release. This review discusses some categories of magnetic core-shell drug carriers based on Fe2O3 and Fe3O4 as the core, and different shells such as poly(lactic-co-glycolic acid), poly(vinylpyrrolidone), chitosan, silica, calcium silicate, metal, and lipids. In addition, the review addresses their recent potential applications for cancer treatment.

Functional Diagnostic and Therapeutic Nanoconstructs for Efficient Probing of Circulating Tumor Cells

The circulation of tumor cells in peripheral blood is mostly recognized as a prerequisite for cancer progression or systemic invasion, and it correlates with the pivotal hallmark of malignancies known as metastasis. Multiple detection schemes for circulating tumor cells (CTCs) have emerged as the most discerning criteria for monitoring the outcome of anticancer therapy. Therefore, there has been a tremendous increase in the use of robust nanostructured platforms for observation of these mobile tumor cells through various simultaneous diagnosis and treatment regimens developed from conventional techniques. This review seeks to give detailed information about the nature of CTCs as well as techniques for exploiting specific biomarkers to help monitor cancer via detection, capturing, and analysis of unstable tumor cells. We will further discuss nanobased diagnostic interventions and novel platforms which have recently been developed from versatile nanomaterials such as polymer nanocomposites, metal organic frameworks, bioderived nanomaterials and other physically responsive particles with desirable intrinsic and external properties. Herein, we will also include in vivo nanotheranostic platforms which have received a lot of attention because of their enormous clinical potential. In all, this review sums up the general potential of key promising nanoinspired systems as well as other advanced strategies under research and those in clinical use.

Magnetic Nano-Systems in Drug Delivery and Biomedical Applications

Nanotechnology is that sphere of technology that involves the participation of biology, chemistry, physics, and engineering sciences. Nanoscale science defines the chemistry and physics of structures lying in the range of 1-100 nm. Among the nanosystems researched, magnetic nanosystems are highlighted due their unique ability, which enables their targeting to specific locations on application of an external magnetic field. The exhibited property of these magnetic nanosystems being super-paramagnetism, there is no retention of magnetic property on removal of the magnetic field, thus enabling a reversion of the targeting process. For effective utilization of these nanosystems, they should be reduced to nanosizes, layered with biocompatible entities, stabilized, and functionalized. In the chapter, synthesis and functionalization and stabilization are elucidated. The biomedical applications such as targeted delivery, MRI, magnetic hyperthermia, tissue engineering, gene delivery, magnetic immunotherapy, magnetic detoxification, and nanomagnetic actuation are discussed.

Toxicity assessment of magnetosomes in different models

Magnetosomes are nanosized iron oxide particles surrounded by lipid membrane synthesized by magnetotactic bacteria (MTB). Magnetosomes have been exploited for a broad range of biomedical and biotechnological applications. Due to their enormous potential in the biomedical field, its safety assessment is necessary. Detailed research on the toxicity of the magnetosomes was not studied so far. This study focuses on the toxicity assessment of magnetosomes in various models such as Human RBC's, WBC's, mouse macrophage cell line (J774), Onion root tip and fish (Oreochromis mossambicus). The toxicity in RBC models revealed that the RBC's are unaltered up to a concentration of 150 µg/ml, and its morphology was not affected. The genotoxicity studies on WBC's showed that there were no detectable chromosomal aberrations up to a concentration of 100 µg/ml. Similarly, there were no detectable morphological changes observed on the magnetosome-treated J774 cells, and the viability of the cells was above 90% at all the tested concentrations. Furthermore, the magnetosomes are not toxic to the fish (O. mossambicus), as no mortality or behavioural changes were observed in the magnetosome-treated groups. Histopathological analysis of the same reveals no damage in the muscle and gill sections. Overall, the results suggest that the magnetosomes are safe at lower concentration and does not pose any potential risk to the ecosystem.

Small versus Large Iron Oxide Magnetic Nanoparticles: Hyperthermia and Cell Uptake Properties

Efficient use of magnetic hyperthermia in clinical cancer treatment requires biocompatible magnetic nanoparticles (MNPs), with improved heating capabilities. Small (~34 nm) and large (~270 nm) Fe₃O₄-MNPs were synthesized by means of a polyol method in polyethylene-glycol (PEG) and ethylene-glycol (EG), respectively. They were systematically investigated by means of X-ray diffraction, transmission electron microscopy and vibration sample magnetometry. Hyperthermia measurements showed that Specific Absorption Rate (SAR) dependence on the external alternating magnetic field amplitude (up to 65 kA/m, 355 kHz) presented a sigmoidal shape, with remarkable SAR saturation values of ~1400 W/gMNP for the small monocrystalline MNPs and only 400 W/gMNP for the large polycrystalline MNPs, in water. SAR values were slightly reduced in cell culture media, but decreased one order of magnitude in highly viscous PEG1000. Toxicity assays performed on four cell lines revealed almost no toxicity for the small MNPs and a very small level of toxicity for the large MNPs, up to a concentration of 0.2 mg/mL. Cellular uptake experiments revealed that both MNPs penetrated the cells through endocytosis, in a time dependent manner and escaped the endosomes with a faster kinetics for large MNPs. Biodegradation of large MNPs inside cells involved an all-or-nothing mechanism.

Magnetic Nanoparticles: Material Engineering and Emerging Applications in Lithography and Biomedicine

We present an interdisciplinary overview of material engineering and emerging applications of iron oxide nanoparticles. We discuss material engineering of nanoparticles in the broadest sense, emphasizing size and shape control, large-area self-assembly, composite/hybrid structures, and surface engineering. This is followed by a discussion of several non-traditional, emerging applications of iron oxide nanoparticles, including nanoparticle lithography, magnetic particle imaging, magnetic guided drug delivery, and positive contrast agents for magnetic resonance imaging. We conclude with a succinct discussion of the pharmacokinetics pathways of iron oxide nanoparticles in the human body -- an important and required practical consideration for any in vivo biomedical application, followed by a brief outlook of the field.

The potential of magneto-electric nanocarriers for drug delivery

INTRODUCTION

The development and design of personalized nanomedicine for better health quality is receiving great attention. In order to deliver and release a therapeutic concentration at the target site, novel nanocarriers (NCs) were designed, for example, magneto-electric (ME) which possess ideal properties of high drug loading, site-specificity and precise on-demand controlled drug delivery.

AREAS COVERED

This review explores the potential of ME-NCs for on-demand and site-specific drug delivery and release for personalized therapeutics. The main features including effect of magnetism, improvement in drug loading, drug transport across blood-brain barriers and on-demand controlled release are also discussed. The future directions and possible impacts on upcoming nanomedicine are highlighted.

EXPERT OPINION

Numerous reports suggest that there is an urgent need to explore novel NC formulations for safe and targeted drug delivery and release at specific disease sites. The challenges of formulation lie in the development of NCs that improve biocompatibility and surface modifications for optimum drug loading/preservation/transmigration and tailoring of electrical-magnetic properties for on-demand drug release. Thus, the development of novel NCs is anticipated to overcome the problems of targeted delivery of therapeutic agents with desired precision that may lead to better patient compliance.

Revisiting 30 years of biofunctionalization and surface chemistry of inorganic nanoparticles for nanomedicine

In the last 30 years we have assisted to a massive advance of nanomaterials in material science. Nanomaterials and structures, in addition to their small size, have properties that differ from those of larger bulk materials, making them ideal for a host of novel applications. The spread of nanotechnology in the last years has been due to the improvement of synthesis and characterization methods on the nanoscale, a field rich in new physical phenomena and synthetic opportunities. In fact, the development of functional nanoparticles has progressed exponentially over the past two decades. This work aims to extensively review 30 years of different strategies of surface modification and functionalization of noble metal (gold) nanoparticles, magnetic nanocrystals and semiconductor nanoparticles, such as quantum dots. The aim of this review is not only to provide in-depth insights into the different biofunctionalization and characterization methods, but also to give an overview of possibilities and limitations of the available nanoparticles.

Single particle tracking reveals biphasic transport during nanorod magnetophoresis through extracellular matrix

Magnetic drug targeting has been proposed as a means of efficiently targeting drugs to tumors. However, the extracellular matrix (ECM) remains a significant barrier to long-range magnetophoretic transport through the tumor volume. While ensemble measurements of nanoparticle magnetophoresis have been reported, a single particle level understanding of magnetophoretic transport remains at large. We quantify nanorod magnetophoresis through ECM based on single particle observations. We find that smaller diameter particles achieve larger velocities through ECM despite experiencing smaller magnetic forces. Additionally, two interesting dynamics are elucidated. First, 18 nm diameter nanorods experience bimodal stick-slip motion through ECM during static field magnetophoresis, while similar bimodal transport is not observed for 55 nm nor 200 nm diameter nanorods. Second, smaller particles experience larger deviations in their orientation angle with respect to the magnetic field. This work elucidates important dynamics of nanoparticle transport through complex, porous biomaterials that may go unnoticed during ensemble measurements.

Progress in the characterization of bio-functionalized nanoparticles using NMR methods and their applications as MRI contrast agents

Significant progress has been made over the last three decades in the field of NMR, a technique which has proven to have a variety of applications in many scientific disciplines, including nanotechnology. Herein we describe how NMR enables the characterization of nanosystems at different stages of their formation and modification (raw materials, bare or functionalized nanosystems), even making it possible to study in vivo nanoparticle interactions, thereby importantly contributing to nanoparticle design and subsequent optimization. Furthermore, the unique characteristics of nanosystems can open up new prospects for site-targeted, more specific contrast agents, contributing to the development of certain nuclear magnetic resonance applications such as MRI.

Facile one-step coating approach to magnetic submicron particles with poly(ethylene glycol) coats and abundant accessible carboxyl groups

Purpose

Magnetic submicron particles (MSPs) are pivotal biomaterials for magnetic separations in bioanalyses, but their preparation remains a technical challenge. In this report, a facile one-step coating approach to MSPs suitable for magnetic separations was investigated.

Methods

Polyethylene glycol) (PEG) was derived into PEG-bis-(maleic monoester) and maleic monoester-PEG-succinic monoester as the monomers. Magnetofluids were prepared via chemical co-precipitation and dispersion with the monomers. MSPs were prepared via one-step coating of magnetofluids in a water-in-oil microemulsion system of aerosol-OT and heptane by radical co-polymerization of such monomers.

Results

The resulting MSPs contained abundant carboxyl groups, exhibited negligible nonspecific adsorption of common substances and excellent suspension stability, appeared as irregular particles by electronic microscopy, and had submicron sizes of broad distribution by laser scattering. Saturation magnetizations and average particle sizes were affected mainly by the quantities of monomers used for coating magnetofluids, and steric hindrance around carboxyl groups was alleviated by the use of longer monomers of one polymerizable bond for coating. After optimizations, MSPs bearing saturation magnetizations over 46 emu/g, average sizes of 0.32 μm, and titrated carboxyl groups of about 0.21 mmol/g were obtained. After the activation of carboxyl groups on MSPs into N-hydroxysuccinimide ester, biotin was immobilized on MSPs and the resulting biotin-functionalized MSPs isolated the conjugate of streptavidin and alkaline phosphatase at about 2.1 mg/g MSPs; streptavidin was immobilized at about 10 mg/g MSPs and retained 81% ± 18% (n = 5) of the specific activity of the free form.

Conclusion

The facile approach effectively prepares MSPs for magnetic separations.

Orthopaedic applications of nanoparticle-based stem cell therapies

Stem cells have tremendous applications in the field of regenerative medicine and tissue engineering. These are pioneering fields that aim to create new treatments for disease that currently have limited therapies or cures. A particularly popular avenue of research has been the regeneration of bone and cartilage to combat various orthopaedic diseases. Magnetic nanoparticles (MNPs) have been applied to aid the development and translation of these therapies from research to the clinic. This review highlights contemporary research for the applications of iron-oxide-based MNPs for the therapeutic implementation of stem cells in orthopaedics. These MNPs comprise of an iron oxide core, coated with a choice of biological polymers that can facilitate the uptake of MNPs by cells through improving endocytic activity. The combined use of these oxides and the biological polymer coatings meet biological requirements, effectively encouraging the use of MNPs in regenerative medicine. The association of MNPs with stem cells can be achieved via the process of endocytosis resulting in the internalisation of these particles or the attachment to cell surface receptors. This allows for the investigation of migratory patterns through various tracking studies, the targeting of particle-labelled cells to desired locations via the application of an external magnetic field and, finally, for activation stem cells to initiate various cellular responses to induce the differentiation. Characterisation of cell localisation and associated tissue regeneration can therefore be enhanced, particularly for in vivo applications. MNPs have been shown to have the potential to stimulate differentiation of stem cells for orthopaedic applications, without limiting proliferation. However, careful consideration of the use of active agents associated with the MNP is suggested, for differentiation towards specific lineages. This review aims to broaden the knowledge of current applications, paving the way to translate the in vitro and in vivo work into further orthopaedic clinical studies.

Magnetically vectored platforms for the targeted delivery of therapeutics to tumors: history and current status

Superparamagnetic iron oxide nanoparticles (SPIONs) are being developed as vehicles for the selective targeting of therapeutics and bioactive compounds. Presented herein is a brief review of the history of approaches to magnetic-based drug delivery platforms, leading to current concepts of magnetically vectored therapeutics via functionalized SPION-prodrugs. With this background, recent experimental results are discussed that demonstrate the use of shaped external magnetic field gradients, generated by designed configurations of permanent magnets, to drive the concentration/accumulation of modified SPION-prodrug constructs at a tumor site, followed by tumor extravasation and activation of the prodrug within the tumor microenvironment. In order to successfully translate this approach to clinical application, one of the key requirements is the ability to magnetically drive (‘vector’) the SPION to human-scale tumor settings. In this review, various configurations of permanent magnets are described and models are presented that demonstrate that magnetic field gradients can potentially be focused and extended to lengths of several inches in vivo. This modification thereby increases the range of the delivery platform, and offers the potential for the treatment of visceral as well as superficial tumors and for translation from preclinical animal tumor models to clinical settings. The methodology of magnetically vectored prodrug therapeutics, as a means for selective localized targeting of tumor tissue, and minimizing harm to normal tissue, has the additional advantage of raising the therapeutic index compared with that of free drugs, thus, offering great potential as a cancer treatment modality.

Molecular imaging with theranostic nanoparticles

Nanoparticles (NPs) offer diagnostic and therapeutic capabilities not available with small molecules or microscale tools. As the field of molecular imaging has emerged from the blending of molecular biology with medical imaging, NP imaging is increasingly common for both therapeutic and diagnostic applications. The term theranostic describes technology with concurrent and complementary diagnostic and therapeutic capabilities. Although NPs have been FDA-approved for clinical use as transport vehicles for nearly 15 years, full translation of their theranostic potential is incomplete. However, NPs have shown remarkable success in the areas of drug delivery and magnetic resonance imaging. Emerging applications include image-guided resection, optical/photoacoustic imaging in vivo, contrast-enhanced ultrasound, and thermoablative therapy. Diagnosis with NPs in molecular imaging involves the correlation of the signal with a phenotype. The location and intensity of NP signals emanating from a living subject indicate the disease area's size, stage, and biochemical signature. Therapy with NPs uses the image for resection or delivery of a small molecule or RNA therapeutic. Ablation of the affected area is also possible via heat or radioactivity. The ideal theranostic NP includes several features: (1) it selectively and rapidly accumulates in diseased tissue; (2) it reports biochemical and morphological characteristics of the area; (3) it delivers an effective therapeutic; and (4) it is safe and biodegrades with nontoxic byproducts. Such a system contains a central imaging core surrounded by small molecule therapeutics. The system targets via ligands such as IgG and is protected from immune scavengers by a cloak of protective polymer. Although no NP has achieved all of the above criteria, many NPs possess one or more of these features. While the most clinically translatable NPs have been used in the field of magnetic resonance imaging, other types in development are quickly becoming more biocompatible through methods that modify their toxicity and biodistribution profiles. In this Account, we describe diagnostic imaging and therapeutic uses of NPs. We propose and offer examples of five primary types of nanoparticles with concurrent diagnostic and therapeutic uses.

Cell death induced by the application of alternating magnetic fields to nanoparticle-loaded dendritic cells

In this work, the capability of primary, monocyte-derived dendritic cells (DCs) to uptake iron oxide magnetic nanoparticles (MNPs) is assessed and a strategy to induce selective cell death in these MNP-loaded DCs using external alternating magnetic fields (AMFs) is reported. No significant decrease in the cell viability of MNP-loaded DCs, compared to the control samples, was observed after five days of culture. The number of MNPs incorporated into the cytoplasm was measured by magnetometry, which confirmed that 1-5 pg of the particles were uploaded per cell. The intracellular distribution of these MNPs, assessed by transmission electron microscopy, was found to be primarily inside the endosomic structures. These cells were then subjected to an AMF for 30 min and the viability of the blank DCs (i.e. without MNPs), which were used as control samples, remained essentially unaffected. However, a remarkable decrease of viability from approximately 90% to 2-5% of DCs previously loaded with MNPs was observed after the same 30 min exposure to an AMF. The same results were obtained using MNPs having either positive (NH(2)(+)) or negative (COOH(-)) surface functional groups. In spite of the massive cell death induced by application of AMF to MNP-loaded DCs, the number of incorporated magnetic particles did not raise the temperature of the cell culture. Clear morphological changes at the cell structure after magnetic field application were observed using scanning electron microscopy. Therefore, local damage produced by the MNPs could be the main mechanism for the selective cell death of MNP-loaded DCs under an AMF. Based on the ability of these cells to evade the reticuloendothelial system, these complexes combined with an AMF should be considered as a potentially powerful tool for tumour therapy.

[Nanomedicine : Magnetic nanoparticles for drug delivery and hyperthermia - new chances for cancer therapy]

The application of nanotechnology for the treatment, diagnosis, and monitoring of illnesses is summarized under the term nanomedicine. A particularly promising application is attributed to nanoparticular drug delivery systems. The goal of these new carrier systems is the selective enrichment of active substances in diseased tissue structures, an increase in bioavailability, the decrease of the active substance degradation and, above all, the reduction and/or avoidance of unwanted side effects. Apart from numerous nanosystems acting as carriers, the use of iron oxide nanoparticles has to be particularly emphasized. On the one hand, those particles are the carriers of the active substance and, on the other hand, can also be visualized with conventional imaging techniques (x-ray tomography, magnetic resonance imaging), called theranostic. In addition, they can be used for hyperthermia, another important supporting pillar of nanomedicine. Both procedures should lead to a personalized and goal-oriented therapy, which is of special medical and socioeconomic importance in view of the increasing number of cancer patients worldwide.

Large-scale production of magnetosomes by chemostat culture of Magnetospirillum gryphiswaldense at high cell density

BACKGROUND

Magnetotactic bacteria have long intrigued researchers because they synthesize intracellular nano-scale (40-100 nm) magnetic particles composed of Fe3O4, termed magnetosomes. Current research focuses on the molecular mechanisms of bacterial magnetosome formation and its practical applications in biotechnology and medicine. Practical applications of magnetosomes are based on their ferrimagnetism, nanoscale size, narrow size distribution, dispersal ability, and membrane-bound structure. However, the applications of magnetosomes have not yet been developed commercially, mainly because magnetotactic bacteria are difficult to cultivate and consistent, high yields of magnetosomes have not yet been achieved.

RESULTS

We report a chemostat culture technique based on pH-stat feeding that yields a high cell density of Magnetospirillum gryphiswaldense strain MSR-1 in an auto-fermentor. In a large-scale fermentor, the magnetosome yield was significantly increased by adjusting the stirring rate and airflow which regulates the level of dissolved oxygen (DO). Low concentration of sodium lactate (2.3 mmol l-1) in the culture medium resulted in more rapid cell growth and higher magnetosome yield than high concentration of lactate (20 mmol l-1). The optical density of M. gryphiswaldense cells reached 12 OD565 nm after 36 hr culture in a 42 L fermentor. Magnetosome yield and productivity were 83.23 ± 5.36 mg l-1 (dry weight) and 55.49 mg l-1 day-1, respectively, which were 1.99 and 3.32 times higher than the corresponding values in our previous study.

CONCLUSIONS

Compared to previously reported methods, our culture technique with the MSR-1 strain significantly increased cell density, cell yield, and magnetosome yield in a shorter time window and thus reduced the cost of production. The cell density and magnetosome yield reported here are the highest so far achieved with a magnetotactic bacteria. Refinement of this technique will enable further increase of cell density and magnetosome yield.

The in vitro stability and in vivo pharmacokinetics of curcumin prepared as an aqueous nanoparticulate formulation

Curcumin, the natural anticancer drug and its optimum potential is limited due to lack of solubility in aqueous solvent, degradation at alkaline pH and poor tissue absorption. In order to enhance its potency and improve bioavailability, we have synthesized curcumin loaded nanoparticulate delivery system. Unlike free curcumin, it is readily dispersed in aqueous medium, showing narrow size distribution 192 nm ranges (as observed by microscope) with biocompatibility (confocal studies and TNF-alpha assay). Furthermore, it displayed enhanced stability in phosphate buffer saline by protecting encapsulated curcumin against hydrolysis and biotransformation. Most importantly, nanoparticulate curcumin was comparatively more effective than native curcumin against different cancer cell lines under in vitro condition with time due to enhanced cellular uptake resulting in reduction of cell viability by inducing apoptosis. Molecular basis of apoptosis studied by western blotting revealed blockade of nuclear factor kappa B (NFkappaB) and its regulated gene expression through inhibition of IkappaB kinase and Akt activation. In mice, nanoparticulate curcumin was more bioavailable and had a longer half-life than native curcumin as revealed from pharmacokinetics study. Thus, the results demonstrated nanoparticulate curcumin may be useful as a potential anticancer drug for treatment of various malignant tumors.