Superparamagnetic agents in magnetic resonance imaging: physicochemical characteristics and clinical applications. A review

Translational applications of magnetic nanocellulose composites

Nanocellulose has emerged as a potential 'green' material owing to its inimitable properties. Furthermore, the significant development in technology has facilitated the design of multidimensional nanocellulose structures, including one-dimensional (1D: microparticles and nanofibers), two-dimensional (2D: coatings), and three-dimensional (3D: hydrogels/ferrogels) composites. In this case, nanocellulose composites blended with magnetic nanoparticles represent a new class of hybrid materials with improved biocompatibility and biodegradability. The application field of magnetic nanocellulose composites (MNCs) ranges from biomedicine and the environment to catalysis and sensing. In this review, we present the major applications of MNCs, emphasizing their innovative benefits and how they interconnect with translational applications in clinics and the environment. Additionally, we focus on the synthesis techniques and role of different additives in the fabrication of MNCs for achieving extremely precise and intricate tasks related to real-world applications. Subsequently, we reveal the recent interdisciplinary research on MNCs and discuss their mechanical, tribological, electrochemical, magnetic, and biological phenomena. Finally, this review concludes with a portrayal of computational modelling together with a glimpse of the various translational applications of MNCs. Therefore, it is anticipated that the current review will provide the readers with an extensive opportunity and a more comprehensive depiction related to the types, properties, and applications of MNCs.

Chitosan- and hyaluronic acid-based nanoarchitectures in phototherapy: Combination cancer chemotherapy, immunotherapy and gene therapy

Cancer phototherapy has been introduced as a new potential modality for tumor suppression. However, the efficacy of phototherapy has been limited due to a lack of targeted delivery of photosensitizers. Therefore, the application of biocompatible and multifunctional nanoparticles in phototherapy is appreciated. Chitosan (CS) as a cationic polymer and hyaluronic acid (HA) as a CD44-targeting agent are two widely utilized polymers in nanoparticle synthesis and functionalization. The current review focuses on the application of HA and CS nanostructures in cancer phototherapy. These nanocarriers can be used in phototherapy to induce hyperthermia and singlet oxygen generation for tumor ablation. CS and HA can be used for the synthesis of nanostructures, or they can functionalize other kinds of nanostructures used for phototherapy, such as gold nanorods. The HA and CS nanostructures can combine chemotherapy or immunotherapy with phototherapy to augment tumor suppression. Moreover, the CS nanostructures can be functionalized with HA for specific cancer phototherapy. The CS and HA nanostructures promote the cellular uptake of genes and photosensitizers to facilitate gene therapy and phototherapy. Such nanostructures specifically stimulate phototherapy at the tumor site, with particle toxic impacts on normal cells. Moreover, CS and HA nanostructures demonstrate high biocompatibility for further clinical applications.

Magnetic Nanoparticles for Biomedical and Imaging Applications

Magnetic nanoparticles (MNPs) are a class of nanomaterials composed of metals such as cobalt, nickel, and iron with paramagnetic, ferromagnetic, or superparamagnetic properties [...].

Emerging Strategies of Engineering and Tracking Dendritic Cells for Cancer Immunotherapy

Dendritic cells (DCs), a kind of specialized immune cells, play key roles in antitumor immune response and promotion of innate and adaptive immune responses. Recently, many strategies have been developed to utilize DCs in cancer therapy, such as delivering antigens and adjuvants to DCs and using scaffold to recruit and activate DCs. Here we outline how different DC subsets influence antitumor immunity, summarize the FDA-approved vaccines and cancer vaccines under clinical trials, discuss the strategies for engineering DCs and noninvasive tracking of DCs to improve antitumor immunotherapy, and reveal the potential of artificial neural networks for the design of DC based vaccines.

Recent advances of polymer based nanosystems in cancer management

Cancer is still one of the leading causes of death worldwide. Nanotechnology, particularly nanoparticle-based platforms, is at the leading edge of current cancer management research. Polymer-based nanosystems have piqued the interest of researchers owing to their many benefits over other conventional drug delivery systems. Polymers derived from both natural and synthetic sources have various biomedical applications due to unique qualities like porosity, mechanical strength, biocompatibility, and biodegradability. Polymers such as poly(lactic-co-glycolic acid) (PLGA), polycaprolactone (PCL), and polyethylene glycol (PEG) have been approved by the USFDA and are being researched for drug delivery applications. They have been reported to be potential carriers for drug loading and are used in theranostic applications. In this review, we have primarily focused on the aforementioned polymers and their conjugates. In addition, the therapeutic and diagnostic implications of polymer-based nanosystems have been briefly reviewed. Furthermore, the safety of the developed polymeric formulations is crucial, and we have discussed their biocompatibility in detail. This article also discusses recent developments in block co-polymer-based nanosystems for cancer treatment. The review ends with the challenges of clinical translation of polymer-based nanosystems in drug delivery for cancer therapy.

Formation of hydrated PEG layers on magnetic iron oxide nanoflowers shows internal magnetisation dynamics and generates high in-vivo efficacy for MRI and magnetic hyperthermia

Multicore magnetic iron oxide nanoparticles, nanoflowers (NFs), have potential biomedical applications as efficient mediators for AC-magnetic field hyperthermia and as contrast agents for magnetic resonance imaging due to their strong magnetic responses arising from complex internal magnetic ordering. To realise these applications amenable surface chemistry must be engineered that maintain particle dispersion. Here a catechol-derived grafting approach is described to strongly bind polyethylene glycol (PEG) to NFs and provide stable hydrogen-bonded hydrated layers that ensure good long-term colloidal stability in buffers and media even at clinical MRI field strength and high concentration. The approach enables the first comprehensive study into the MRI (relaxivity) and hyperthermic (SAR) efficiencies of fully dispersed NFs. The predominant role of internal magnetisation dynamics in providing high relaxivity and SAR is confirmed, and it is shown that these properties are unaffected by PEG molecular weight or corona formation in biological environments. This result is in contrast to traditional single core nanoparticles which have significantly reduced SAR and relaxivity upon PEGylation and on corona formation, attributed to reduced Brownian contributions and weaker NP solvent interactions. The PEGylated NF suspensions described here exhibit usable blood circulation times and promising retention of relaxivity in-vivo due to the strongly anchored PEG layer. This approach to biomaterials design addresses the challenge of maintaining magnetic efficiency of magnetic nanoparticles in-vivo for applications as theragnostic agents. STATEMENT OF SIGNIFICANCE: : Application of multicore magnetic iron-oxide nanoflowers (NFs) as efficient mediators for AC-field hyperthermia and as contrast agents for MR imaging has been limited by lack of colloidal stability in complex media and biosystems. The optimized materials design presented is shown to reproducibly provide PEG grafted NF suspensions of exceptional colloidal stability in buffers and complex media, with significant hyperthermic and MRI utility which is unaffected by PEG length, anchoring group or bio-molecular adsorption. Deposition in the selected pancreatic model mirrors liposomal formulations providing a quantifiable probe of tissue-level liposome deposition and relaxivity is retained in the tumour microenvironment. Hence the biomaterials design addresses the longstanding challenges of maintaining the in vivo magnetic efficiency of nanoparticles as theragnostic agents.

Teratological effects of titanium dioxide nanoparticles in mice embryo

Nanoparticles have numerous applications related to human uses. Titanium dioxide nanoparticles (TiO₂-NPs) are extensively used in many daily utilities. The small size particles and larger uses in the industry have led them to become a threatening entity to the living organisms. The unchecked use and dumping in the environment poses a significant toxicological risk to the developing mammalian embryo. The present study was conducted to determine the developmental toxicity and teratogenic effects of TiO₂-NPs in murine embryos. The TiO₂-NPs were introduced intravenously into pregnant mice graded as T1 (0.52 mg/g BW), T2 (0.7 mg/g BW), and T3 (1.05 mg/g BW) along with control with no dose administration T0 (0.00 mg/g BW). Results recorded after 14 days were resorbed fetuses, dropped wrist, hemorrhages, sacral hygromas, and kinked tails. It was concluded that the exposure of TiO₂-NPs in mentioned doses from any source may lead to deleterious effects on the development of an embryo.

Magnetic particle imaging: tracer development and the biomedical applications of a radiation-free, sensitive, and quantitative imaging modality

Magnetic particle imaging (MPI) is an emerging tracer-based modality that enables real-time three-dimensional imaging of the non-linear magnetisation produced by superparamagnetic iron oxide nanoparticles (SPIONs), in the presence of an external oscillating magnetic field. As a technique, it produces highly sensitive radiation-free tomographic images with absolute quantitation. Coupled with a high contrast, as well as zero signal attenuation at-depth, there are essentially no limitations to where that can be imaged within the body. These characteristics enable various biomedical applications of clinical interest. In the opening sections of this review, the principles of image generation are introduced, along with a detailed comparison of the fundamental properties of this technique with other common imaging modalities. The main feature is a presentation on the up-to-date literature for the development of SPIONs tailored for improved imaging performance, and developments in the current and promising biomedical applications of this emerging technique, with a specific focus on theranostics, cell tracking and perfusion imaging. Finally, we will discuss recent progress in the clinical translation of MPI. As signal detection in MPI is almost entirely dependent on the properties of the SPION employed, this work emphasises the importance of tailoring the synthetic process to produce SPIONs demonstrating specific properties and how this impacts imaging in particular applications and MPI's overall performance.

DNA/Magnetic Nanoparticles Composite to Attenuate Glass Surface Nanotopography for Enhanced Mesenchymal Stem Cell Differentiation

Mesenchymal stem cells (MSCs) have extensive pluripotent potential to differentiate into various cell types, and thus they are an important tool for regenerative medicine and biomedical research. In this work, the differentiation of hTERT-transduced adipose-derived MSCs (hMSCs) into chondrocytes, adipocytes and osteoblasts on substrates with nanotopography generated by magnetic iron oxide nanoparticles (MNPs) and DNA was investigated. Citrate-stabilized MNPs were synthesized by the chemical co-precipitation method and sized around 10 nm according to microscopy studies. It was shown that MNPs@DNA coatings induced chondrogenesis and osteogenesis in hTERT-transduced MSCs. The cells had normal morphology and distribution of actin filaments. An increase in the concentration of magnetic nanoparticles resulted in a higher surface roughness and reduced the adhesion of cells to the substrate. A glass substrate modified with magnetic nanoparticles and DNA induced active chondrogenesis of hTERT-transduced MSC in a twice-diluted differentiation-inducing growth medium, suggesting the possible use of nanostructured MNPs@DNA coatings to obtain differentiated cells at a reduced level of growth factors.

Magnetic nanoparticles in theranostics of malignant melanoma

Malignant melanoma is an aggressive tumor with a tendency to metastasize early and with an increasing incidence worldwide. Although in early stage, melanoma is well treatable by excision, the chances of cure and thus the survival rate decrease dramatically after metastatic spread. Conventional treatment options for advanced disease include surgical resection of metastases, chemotherapy, radiation, targeted therapy and immunotherapy. Today, targeted kinase inhibitors and immune checkpoint blockers have for the most part replaced less effective chemotherapies. Magnetic nanoparticles as novel agents for theranostic purposes have great potential in the treatment of metastatic melanoma. In the present review, we provide a brief overview of treatment options for malignant melanoma with different magnetic nanocarriers for theranostics. We also discuss current efforts of designing magnetic particles for combined, multimodal therapies (e.g., chemotherapy, immunotherapy) for malignant melanoma.

Magnetic nanocellulose: A potential material for removal of dye from water

In this study, cellulose nanofibers are used as a template to synthesise magnetic nanoparticles with a uniform size distribution. Magnetic nanoparticles are grafted on the surface of nanofibers via in situ hydrolysis of metal precursors at room temperature. Effects of different concentrations of nanofibers on the morphology, the crystallite size of magnetic nanoparticles, and the thermal and magnetic properties of the membrane produced from the cellulose nanofibers decorated with magnetic nanoparticles are examined. The sizes of magnetic nanoparticles produced in this study are below 20 nm, and the crystallite size of the nanoparticles is in the range of 96-130 Å. The flexible magnetic membranes containing a high concentration of magnetic nanoparticles (83-60 wt%) showed superparamagnetic behaviour with very high magnetic properties (67.4-38.5 emu g^-1). The magnetic membrane was then used as an environmentally friendly, low-cost catalyst in a sulphate radical-based advanced oxidation process. The membranes successfully activated peroxymonosulphate (PMS) to remove Rhodamine B (RhB), a common hydrophilic organic dye applied in industry. 94.9 % of the Rhodamine B was degraded in 300 min at room temperature, indicating that the magnetic nanocellulose membrane is highly effective for catalyzing PMS to remove RhB.

Nanomedicine and Onco-Immunotherapy: From the Bench to Bedside to Biomarkers

The broad relationship between the immune system and cancer is opening a new hallmark to explore for nanomedicine. Here, all the common and synergy points between both areas are reviewed and described, and the recent approaches which show the progress from the bench to the beside to biomarkers developed in nanomedicine and onco-immunotherapy.

PLinaS-g-PEG coated magnetic nanoparticles as a contrast agent for hepatocellular carcinoma diagnosis

Among many different types of fabricated nanoparticles, magnetic iron oxide nanoparticles (MNPs) have unique physical and chemical properties and have been widely used due to theirs enhanced permeability and retention effect for biomedical applications. The incorporated theranostic MNPs into biopolymer coatings are currently particular interest to investigators in the fields of nanobiomedicine because of efficiently delivering of various drugs, genes and providing imaging properties. Hepatocellular carcinoma (HCC) is the most prevalent reason of cancer-related deaths, makes it one of the worst malignant tumors in the world. Because, there is a lack of effective treatment methods for HCC, aforementioned magnetic carrier technology with recent innovations could be a promising tool in HCC diagnosis and treatment. Therefore, this study proposes a novel fatty-acid-based polymeric magnetic nanoprobe for diagnosis of hepatocellular tumors using polyethylene glycol (PEG)-terminated polystyrene (PS)-linoleic copolymer coated magnetic iron oxide nanoparticles. MNPs were synthesized by a co-precipitation method and were subsequently coated with a copolymer containing PEG group as termini. Fifty-nanometer-sized MNPs were incorporated into the core of PLinaS-g-PEG nanoparticles. The morphology and size distribution of the bare and magnetic PLinaS-g-PEG were determined by transmission electron microscopy (TEM), and dynamic light scattering (DLS), respectively. MTT and flow cytometry assays showed that PLinaS-g-PEG MNPs demonstrated ultrasentive apoptotic behavior against cancerous cell line, i.e. HepG2 in the culture plate when the fatty acid-containing polymer coated MNPs showed no adverse effect on L929 cell growth. The localization, and accumulation in hepatocytes of PLinaS-g-PEG MNPs without specific targeting ligand was confirmed by fluorescence and confocal microscopy. Therefore, PLinaS-g-PEG MNPs may be potentially used as a unique candidate for diagnosis of hepatocellular carcinomas.

Dynamic cerebral perfusion parameters and magnetic nanoparticle accumulation assessed by AC biosusceptometry

Cerebral blood flow (CBF) assessment is mainly performed by scintigraphy, computed tomography (CT) and magnetic resonance imaging (MRI). New approaches to assess the CBF through the passage of magnetic nanoparticles (MNPs) to blood-brain barrier (BBB) are convenient to help decrease the use of ionizing radiation and unleash the required MRI schedule in clinics. The development of nanomedicine and new biomedical devices, such as the magnetic particle imaging (MPI), enabled new approaches to study dynamic brain blood flow. In this paper, we employed MNPs and the alternating current biosusceptometry (ACB) to study the brain perfusion. We utilized the mannitol, before the MNPs, injection to modulate the BBB permeability and study its effects on the circulation time of the MNPs in the brain of rats. Also, we characterized a new ACB sensor to increase the systems' applicability to study the MNPs' accumulation, especially in the animals' brain. Our data showed that the injection of mannitol increased the circulation time of MNPs in the brain. Also, the mannitol increased the accumulation of MNPs in the brain. This paper suggests the use of the ACB as a tool to study brain perfusion and accumulation of MNPs in studies of new nano agents focused on the brain diagnostics and treatment.

Chemotherapeutic potential of L-carnosine from stimuli-responsive magnetic nanoparticles against breast cancer model

Aim: L-carnosine-coated magnetic nanoparticles (CCMNPs) were developed to enhance chemotherapeutic activity of carnosine-dipeptide. Materials & methods: Surface grafting of MNPs with carnosine was contended by differential scanning calorimetry, infrared spectroscopy and x-ray diffraction. Physicochemical characterization and in vitro cytotoxicity on MCF-7 cell line was carried out. In vivo chemotherapeutic activity and toxicity was assessed by an Ehrlich Ascites tumor model. Results: CCMNPs possessed monodispersed size (120 nm), ζ (-27.3 mV), magnetization (51.52 emu/g) and entrapment efficiency (88.3%) with sustained release rate. CCMNPs showed 2.3-folds lower IC50 values compared with carnosine solution after 48 h. Targeted CCMNPs were specifically accumulated in tumor showing significant reduction in tumor size with no systemic toxicity. Significant reduction in VEGF and cyclin D1 levels were observed. Conclusion: The developed system endowed with responsiveness to an external stimulus can represent a promising magnetically targeted delivery system for carnosine site specific delivery.

Biotechnological approach to induce human fibroblast apoptosis using superparamagnetic iron oxide nanoparticles

Cancer-Associated Fibroblasts (CAFs) contribute to tumour progression and have received significant attention as a therapeutic target. These cells produce growth factors, cytokines and chemokines, stimulating cancer cell proliferation and inhibiting their apoptosis. Recent advances in drug delivery have demonstrated a significant promise of iron oxide nanoparticles in clinics as theranostic agents, mainly due to their magnetic properties. Here, we designed superparamagnetic iron oxide nanoparticles (SPIONs) to induce apoptosis of human fibroblasts. SPIONs were synthesized via co-precipitation method and coated with sodium citrate (SPION_Cit). We assessed the intracellular uptake of SPIONs by human fibroblast cells, as well as their cytotoxicity and ability to induce thermal effects under the magnetic field. The efficiency and time of nanoparticle internalization were assessed by Prussian Blue staining, flow cytometry and transmission electron microscopy. SPIONs_Cit were detected in the cytoplasm of human fibroblasts 15 min after in vitro exposure, entering into cells mainly via endocytosis. Analyses through Cell Titer Blue assay, AnnexinV-fluorescein isothiocyanate (FITC) and propidium iodide (PI) cellular staining demonstrated that concentrations below 8 × 10^-2 mg/mL of SPIONs_Cit did not alter cell viability of human fibroblast. Furthermore, it was also demonstrated that SPIONs_Cit associated with alternating current magnetic field were able to induce hyperthermia and human fibroblast cell death in vitro, mainly through apoptosis (83.5%), activating caspase 8 (extrinsic apoptotic via) after a short exposure period. Collectively these findings suggest that our nanoplatform is biocompatible and can be used for therapeutic purposes in human biological systems, such as inducing apoptosis of CAFs.

Biocompatible Layers Obtained from Functionalized Iron Oxide Nanoparticles in Suspension

Iron oxide nanoparticles have been extensively studied for challenges in applicable areas such as medicine, pharmacy, and the environment. The functionalization of iron oxide nanoparticles with dextran opens new prospects for application. Suspension characterization methods such as dynamic light scattering (DLS) and zeta potential (ZP) have allowed us to obtain information regarding the stability and hydrodynamic diameter of these suspended particles. For rigorous characterization of the suspension of dextran-coated iron oxide nanoparticles (D-MNPs), studies have been performed using ultrasound measurements. The results obtained from DLS and ZP studies were compared with those obtained from ultrasound measurements. The obtained results show a good stability of D-MNPs. A comparison between the D-MNP dimension obtained from transmission electron microscopy (TEM), X-ray diffraction (XRD), and DLS studies was also performed. A scanning electron spectroscopy (SEM) image of a surface D-MNP layer obtained from the stable suspension shows that the particles are spherical in shape. The topographies of the elemental maps of the D-MNP layer showed a uniform distribution of the constituent elements. The homogeneity of the layer was also observed. The morphology of the HeLa cells incubated for 24 and 48 h with the D-MNP suspension and D-MNP layers did not change relative to the morphology presented by the control cells. The cytotoxicity studies conducted at different time intervals have shown that a slight decrease in the HeLa cell viability after 48 h of incubation for both samples was observed.

Hybrid Magnetic Nanostructures For Cancer Diagnosis And Therapy

Cancer is the second disease in the world from the point of view of mortality. The conventional routes of treatment were found to be not sufficient and thus alternative ways are imposed. The use of hybrid, magnetic nanostructures is a promising way for simultaneous targeted diagnosis and treatment of various types of cancer. For this reason, the development of core@shell structures was found to be an efficient way to develop stable, biocompatible, non-toxic carriers with shell-dependent internalization capacity in cancer cells. So, the multicomponent approach can be the most suitable way to assure the multifunctionality of these nanostructures to achieve the desired/necessary properties. The in vivo stability is mostly assured by the coating of the magnetic core with various polymers (including polyethylene glycol, silica etc.), while the targeting capacity is mostly assured by the decoration of these nanostructures with folic acid. Unfortunately, there are also some limitations related to the multilayered approach. For instance, the increasing of the thickness of layers leads to a decrease the magnetic properties, (hyperthermia and guiding ability in the magnetic field, for instance), the outer shell should contain the targeting molecules (as well as the agents helping the internalization into the cancer cells), etc.

Simulation on the Factors Affecting the Crystallization Process of FeNi Alloy by Molecular Dynamics

This paper investigates the crystallization process of FeNi alloys with different impurity concentrations of Ni(x) [x = 10% (Fe₉₀Ni₁₀), 20% (Fe₈₀Ni₂₀), 30% (Fe₇₀Ni₃₀), 40% (Fe₆₀Ni₄₀), and 50% (Fe₅₀Ni₅₀)] at temperature (T) = 300 K and Fe₇₀Ni₃₀ at heating rates of 4 × 10¹², 4 × 10¹³, and 4 × 10¹⁴ K/s at different temperatures, T = 300, 400, 500, 600, 700, 900, 1100, and 1300 K. Molecular dynamics models with the Sutton-Chen embedded interaction potential and recirculating boundary conditions are used to calculate the molecular parameters of alloys, such as radial distribution function, total energy of the system (E _tot), size (l), and crystallization temperature (through the relationship between E _tot and T). The common neighborhood analysis method is used to confirm the theoretical results of crystallization for Fe-Fe, Fe-Ni, and Ni-Ni. The annealing process did not have an effect on the crystallization process of FeNi alloys. The effect of Ni content, heating rate, and annealing time on structural unit numbers, such as face-centered cubic, hexagonal close-packed, blocked cubic center, and amorphous, and the crystallization process of FeNi alloys is also investigated.

Delivering Combination Chemotherapies and Targeting Oncogenic Pathways via Polymeric Drug Delivery Systems

The side-effects associated with chemotherapy necessitates better delivery of chemotherapeutics to the tumor. Nanoparticles can load higher amounts of drug and improve delivery to tumors, increasing the efficacy of treatment. Polymeric nanoparticles, in particular, have been used extensively for chemotherapeutic delivery. This review describes the efforts made to deliver combination chemotherapies and inhibit oncogenic pathways using polymeric drug delivery systems. Combinations of chemotherapeutics with other drugs or small interfering RNA (siRNA) combinations have been summarized. Special attention is given to the delivery of drug combinations that involve either paclitaxel or doxorubicin, two popular chemotherapeutics in clinic. Attempts to inhibit specific pathways for oncotherapy have also been described. These include inhibition of oncogenic pathways (including those involving HER2, EGFR, MAPK, PI3K/Akt, STAT3, and HIF-1α), augmentation of apoptosis by inhibiting anti-apoptosis proteins (Bcl-2, Bcl-xL, and survivin), and targeting dysregulated pathways such as Wnt/β-catenin and Hedgehog.

A Review of Magnetic Particle Imaging and Perspectives on Neuroimaging

Magnetic particle imaging is an emerging tomographic technique with the potential for simultaneous high-resolution, high-sensitivity, and real-time imaging. Magnetic particle imaging is based on the unique behavior of superparamagnetic iron oxide nanoparticles modeled by the Langevin theory, with the ability to track and quantify nanoparticle concentrations without tissue background noise. It is a promising new imaging technique for multiple applications, including vascular and perfusion imaging, oncology imaging, cell tracking, inflammation imaging, and trauma imaging. In particular, many neuroimaging applications may be enabled and enhanced with magnetic particle imaging. In this review, we will provide an overview of magnetic particle imaging principles and implementation, current applications, promising neuroimaging applications, and practical considerations.

In vivo fate of free and encapsulated iron oxide nanoparticles after injection of labelled stem cells

Nanoparticle contrast agents are useful tools to label stem cells and monitor the in vivo bio-distribution of labeled cells in pre-clinical models of disease. In this context, understanding the in vivo fate of the particles after injection of labelled cells is important for their eventual clinical use as well as for the interpretation of imaging results. We examined how the formulation of superparamagnetic iron oxide nanoparticles (SPIONs) impacts the labelling efficiency, magnetic characteristics and fate of the particles by comparing individual SPIONs with polyelectrolyte multilayer capsules containing SPIONs. At low labelling concentration, encapsulated SPIONs served as an efficient labelling agent for stem cells. The bio-distribution after intra-cardiac injection of labelled cells was monitored longitudinally by MRI and as an endpoint by inductively coupled plasma-optical emission spectrometry. The results suggest that, after being released from labelled cells after cell death, both formulations of particles are initially stored in liver and spleen and are not completely cleared from these organs 2 weeks post-injection.

Overcoming the Blood-Brain Barrier: The Role of Nanomaterials in Treating Neurological Diseases

Therapies directed toward the central nervous system remain difficult to translate into improved clinical outcomes. This is largely due to the blood-brain barrier (BBB), arguably the most tightly regulated interface in the human body, which routinely excludes most therapeutics. Advances in the engineering of nanomaterials and their application in biomedicine (i.e., nanomedicine) are enabling new strategies that have the potential to help improve our understanding and treatment of neurological diseases. Herein, the various mechanisms by which therapeutics can be delivered to the brain are examined and key challenges facing translation of this research from benchtop to bedside are highlighted. Following a contextual overview of the BBB anatomy and physiology in both healthy and diseased states, relevant therapeutic strategies for bypassing and crossing the BBB are discussed. The focus here is especially on nanomaterial-based drug delivery systems and the potential of these to overcome the biological challenges imposed by the BBB. Finally, disease-targeting strategies and clearance mechanisms are explored. The objective is to provide the diverse range of researchers active in the field (e.g., material scientists, chemists, engineers, neuroscientists, and clinicians) with an easily accessible guide to the key opportunities and challenges currently facing the nanomaterial-mediated treatment of neurological diseases.

Theranostics and contrast agents for magnetic resonance imaging

BACKGROUND

Magnetic resonance imaging is one of the diagnostic tools that uses magnetic particles as contrast agents. It is noninvasive methodology which provides excellent spatial resolution. Although magnetic resonance imaging offers great temporal and spatial resolution and rapid in vivo images acquisition, it is less sensitive than other methodologies for small tissue lesions, molecular activity or cellular activities. Thus, there is a desire to develop contrast agents with higher efficiency. Contrast agents are known to shorten both T1 and T2. Gadolinium based contrast agents are examples of T1 agents and iron oxide contrast agents are examples of T2 agents. In order to develop high relaxivity agents, gadolinium or iron oxide-based contrast agents can be synthesized via conjugation with targeting ligands or functional moiety for specific interaction and achieve accumulation of contrast agents at disease sites.

MAIN BODY

This review discusses the principles of magnetic resonance imaging and recent efforts focused on specificity of contrast agents on specific organs such as liver, blood, lymph nodes, atherosclerotic plaque, and tumor. Furthermore, we will discuss the combination of theranostic such as contrast agent and drug, contrast agent and thermal therapy, contrast agent and photodynamic therapy, and neutron capture therapy, which can provide for cancer diagnosis and therapeutics.

CONCLUSION

These applications of magnetic resonance contrast agents demonstrate the usefulness of theranostic agents for diagnosis and treatment.

Overendocytosis of superparamagnetic iron oxide particles increases apoptosis and triggers autophagic cell death in human osteosarcoma cell under a spinning magnetic field

The toxicity of superparamagnetic iron oxide nanoparticles (SPIONs) is still a vital topic of debate and the mechanisms remain unclear. In the present study, overdose SPIONs could induce osteosarcoma cell death and the effects were exaggerated when combined with spinning magnetic field (SMF). In the combination group, mitochondrial transmembrane potential decrease more obviously and reactive oxygen species (ROS) was found to generate much higher in line with that of the apoptosis ratio. Meantime, amount of autophagy was induced. Inhibiting the autophagy generation by 3-methyladenine (3-MA) increase cell viability but decrease the caspase 3/7 and caspase 8 activities in combination groups, and inhibiting apoptosis took the same effect. In the end, the SPIONs effects on xenograft mice was examed by intratumoral injection. The result showed that the combination group could greatly decrease the tumor volume and prolong the lifespan of mice. In sum, the result indicated that overdose SPIONs induced ROS generation, and excessive ROS induced by combination of SPIONs and SMF contribute to autophagy formation, which play a apoptosis-promoting role that formed as a platform to recruits initiate the caspase activities.

Peptide functionalized magneto-plasmonic nanoparticles obtained by microfluidics for inhibition of β-amyloid aggregation

Synthesis of magneto-plasmonic nanoparticles for the inhibition of β-amyloid fibril formation.

Basic Pulse Sequences in Magnetic Resonance Imaging

Magnetic resonance images are obtained by a combination of different radiofrequency pulses and gradient waveforms applied to the subject inside a magnetic field. There are multiple pulse sequences used in clinical and preclinical studies adjusted to whatever physician or researches want to analyze, from basic anatomic images to accurate diagnostic techniques as diffusion, perfusion, or functional imaging. In this chapter, we present the most used radiofrequency pulse combinations of the two groups of sequences available in magnetic resonance imaging: spin-echo and gradient-echo sequences.

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.

Advanced Contrast Agents for Multimodal Biomedical Imaging Based on Nanotechnology

Clinical imaging modalities have reached a prominent role in medical diagnosis and patient management in the last decades. Different image methodologies as Positron Emission Tomography, Single Photon Emission Tomography, X-Rays, or Magnetic Resonance Imaging are in continuous evolution to satisfy the increasing demands of current medical diagnosis. Progress in these methodologies has been favored by the parallel development of increasingly more powerful contrast agents. These are molecules that enhance the intrinsic contrast of the images in the tissues where they accumulate, revealing noninvasively the presence of characteristic molecular targets or differential physiopathological microenvironments. The contrast agent field is currently moving to improve the performance of these molecules by incorporating the advantages that modern nanotechnology offers. These include, mainly, the possibilities to combine imaging and therapeutic capabilities over the same theranostic platform or improve the targeting efficiency in vivo by molecular engineering of the nanostructures. In this review, we provide an introduction to multimodal imaging methods in biomedicine, the sub-nanometric imaging agents previously used and the development of advanced multimodal and theranostic imaging agents based in nanotechnology. We conclude providing some illustrative examples from our own laboratories, including recent progress in theranostic formulations of magnetoliposomes containing ω-3 poly-unsaturated fatty acids to treat inflammatory diseases, or the use of stealth liposomes engineered with a pH-sensitive nanovalve to release their cargo specifically in the acidic extracellular pH microenvironment of tumors.

Are engineered nano iron oxide particles safe? an environmental risk assessment by probabilistic exposure, effects and risk modeling

Nano iron oxide particles are beneficial to our daily lives through their use in paints, construction materials, biomedical imaging and other industrial fields. However, little is known about the possible risks associated with the current exposure level of engineered nano iron oxides (nano-FeOX) to organisms in the environment. The goal of this study was to predict the release of nano-FeOX to the environment and assess their risks for surface waters in the EU and Switzerland. The material flows of nano-FeOX to technical compartments (waste incineration and waste water treatment plants) and to the environment were calculated with a probabilistic modeling approach. The mean value of the predicted environmental concentrations (PECs) of nano-FeOX in surface waters in the EU for a worst-case scenario (no particle sedimentation) was estimated to be 28 ng/l. Using a probabilistic species sensitivity distribution, the predicted no-effect concentration (PNEC) was determined from ecotoxicological data. The risk characterization ratio, calculated by dividing the PEC by PNEC values, was used to characterize the risks. The mean risk characterization ratio was predicted to be several orders of magnitude smaller than 1 (1.4 × 10^-4). Therefore, this modeling effort indicates that only a very limited risk is posed by the current release level of nano-FeOX to organisms in surface waters. However, a better understanding of the hazards of nano-FeOX to the organisms in other ecosystems (such as sediment) needs to be assessed to determine the overall risk of these particles to the environment.

Targeted Magnetic Nanotheranostics of Cancer

Current advances in targeted magnetic nanotheranostics are summarized in this review. Unique structural, optical, electronic and thermal properties of magnetic materials in nanometer scale are attractive in the field of biomedicine. Magnetic nanoparticles functionalized with therapeutic molecules, ligands for targeted delivery, fluorescent and other chemical agents can be used for cancer diagnostic and therapeutic purposes. High selectivity, small size, and low immunogenicity of synthetic nucleic acid aptamers make them attractive delivery agents for therapeutic purposes. Properties, production and functionalization of magnetic nanoparticles and aptamers as ligands for targeted delivery are discussed herein. In recent years, magnetic nanoparticles have been widely used in diagnostic methods, such as scintigraphy, single photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI), and Raman spectroscopy. Therapeutic purposes of magnetic nanoconstructions are also promising. They are used for effective drug delivery, magnetic mediated hypertermia, and megnetodynamic triggering of apoptosis. Thus, magnetic nanotheranostics opens a new venue for complex differential diagnostics, and therapy of metastatic cancer.

Magnetic nanoparticles for precision oncology: theranostic magnetic iron oxide nanoparticles for image-guided and targeted cancer therapy

Recent advances in the development of magnetic nanoparticles (MNPs) have shown promise in the development of new personalized therapeutic approaches for clinical management of cancer patients. The unique physicochemical properties of MNPs endow them with novel multifunctional capabilities for imaging, drug delivery and therapy, which are referred to as theranostics. To facilitate the translation of those theranostic MNPs into clinical applications, extensive efforts have been made on designing and improving biocompatibility, stability, safety, drug-loading ability, targeted delivery, imaging signal and thermal- or photodynamic response. In this review, we provide an overview of the physicochemical properties, toxicity and theranostic applications of MNPs with a focus on magnetic iron oxide nanoparticles.

Super-paramagnetic loaded nanoparticles based on biological macromolecules for in vivo targeted MR imaging

Target-specific MRI contrast agent based on super-paramagnetic iron oxide-chitosan-folic acid (SPIONP-CS-FA) nanoparticles was fabricated by using an ionotropic gelation method, which involved the loading of SPIONPs at various concentrations into CS-FA nanoparticles by electrostatic interaction. The SPIONP-CS-FA nanoparticles were characterized by ATR-FTIR, XRD, TEM, and VSM techniques. This study revealed that the advantages of this system would be green fabrication, low cytotoxicity at iron concentrations ranging from 0.52 mg/L to 4.16 mg/L, and high water stability (pH 6) at 4°C over long periods. Average particle size and positive zeta-potential of the SPIONP-CS-FA nanoparticles was found to be 130 nm with narrow size distribution and 42 mV, respectively. In comparison to SPIONP-0.5-CS nanoparticles, SPIONP-0.5-CS-FA nanoparticles showed higher and specific cellular uptake levels into human cervical adenocarcinoma cells due to the presence of folate receptors, while in vivo results (Wistar rat) indicated that only liver tissue showed significant decreases in MR image intensity on T2 weighted images and T2* weighted images after post-injection, in comparison with other organs. Our results demonstrated that SPIONP-CS-FA nanoparticles can be applied as an either tumor or organ specific MRI contrast agents.

QUANTIFYING THE MOTION OF MAGNETIC PARTICLES IN EXCISED TISSUE: EFFECT OF PARTICLE PROPERTIES AND APPLIED MAGNETIC FIELD

This article presents a method to investigate how magnetic particle characteristics affect their motion inside tissues under the influence of an applied magnetic field. Particles are placed on top of freshly excised tissue samples, a calibrated magnetic field is applied by a magnet underneath each tissue sample, and we image and quantify particle penetration depth by quantitative metrics to assess how particle sizes, their surface coatings, and tissue resistance affect particle motion. Using this method, we tested available fluorescent particles from Chemicell of four sizes (100 nm, 300 nm, 500 nm, and 1 µm diameter) with four different coatings (starch, chitosan, lipid, PEG/P) and quantified their motion through freshly excised rat liver, kidney, and brain tissues. In broad terms, we found that the applied magnetic field moved chitosan particles most effectively through all three tissue types (as compared to starch, lipid, and PEG/P coated particles). However, the relationship between particle properties and their resulting motion was found to be complex. Hence, it will likely require substantial further study to elucidate the nuances of transport mechanisms and to select and engineer optimal particle properties to enable the most effective transport through various tissue types under applied magnetic fields.

Preparation and characterization of an iron oxide-hydroxyapatite nanocomposite for potential bone cancer therapy

Recently, multifunctional magnetic nanostructures have been found to have potential applications in biomedical and tissue engineering. Iron oxide nanoparticles are biocompatible and have distinctive magnetic properties that allow their use in vivo for drug delivery and hyperthermia, and as T2 contrast agents for magnetic resonance imaging. Hydroxyapatite is used frequently due to its well-known biocompatibility, bioactivity, and lack of toxicity, so a combination of iron oxide and hydroxyapatite materials could be useful because hydroxyapatite has better bone-bonding ability. In this study, we prepared nanocomposites of iron oxide and hydroxyapatite and analyzed their physicochemical properties. The results suggest that these composites have superparamagnetic as well as biocompatible properties. This type of material architecture would be well suited for bone cancer therapy and other biomedical applications.

Use of ultrasmall superparamagnetic iron oxide particles for imaging carotid atherosclerosis

Based on the results of histopathological studies, inflammation within atherosclerotic tissue is now widely accepted as a key determinant of the disease process. Conventional imaging methods can highlight the location and degree of luminal stenosis but not the inflammatory activity of the plaque. Iron oxide-based MRI contrast media particularly ultrasmall supermagnetic particles of iron oxide have shown potential in assessing atheromatous plaque inflammation and in determining efficacy of antiatherosclerosis pharmacological treatments. In this paper, we review current data on the use of ultrasmall superparamagnetic iron oxides in atherosclerosis imaging with focus on ferumoxtran-10 and ferumoxytol. The basic chemistry, pharmacokinetics and dynamics, potential applications, limitations and future perspectives of these contrast media nanoparticles are discussed.

Current progress in nanotechnology applications for diagnosis and treatment of kidney diseases

Significant progress has been made in nanomedicine, primarily in the form of nanoparticles, for theranostic applications to various diseases. A variety of materials, both organic and inorganic, have been used to develop nanoparticles with promise to achieve improved efficacy in medical applications as well as reduced systemic side effects compared to current standard of care medical practices. In particular, this article highlights the recent development and application of nanoparticles for diagnosing and treating nephropathologies.