Real-Time Observation and Analysis of Magnetomechanical Actuation of Magnetic Nanoparticles in Cells.

The origin of cell death in the magnetomechanical actuation of cells induced by magnetic nanoparticle motion under low-frequency magnetic fields is still elusive. Here, a miniaturized electromagnet fitted under a confocal microscope is used to observe in real time cells specifically targeted by superparamagnetic nanoparticles and exposed to a low-frequency rotating magnetic field. Our analysis reveals that the lysosome membrane is permeabilized in only a few minutes after the start of magnetic field application, concomitant with lysosome movements toward the nucleus. Those events are associated with disorganization of the tubulin microtubule network and a change in cell morphology. This miniaturized electromagnet will allow a deeper insight into the physical, molecular, and biological process occurring during the magnetomechanical actuation of magnetic nanoparticles.

Iron Oxide Nanoparticles Functionalized with Fucoidan: a Potential Theranostic Nanotool for Hepatocellular Carcinoma.

Fucoidan is a natural sulfated polysaccharide with a large range of biological activities including anticancer and anti-oxidation activities. Hepatocellular carcinoma is the fourth most common aggressive cancer type. The aim of this study was to investigate the bioactivity of free fucoidan versus its vectorization using nanoparticles (NPs) in human hepatoma cells, Huh-7. Iron oxide NPs were functionalized with fucoidan by a one-step surface complexation. NP cellular uptake was quantified by magnetic measurement at various extracellular iron concentrations. Cell invasion and migration were reduced with NPs while free fucoidan increases these events at low fucoidan concentration (≤0.5 µM). Concomitantly, a high decrease of reactive oxygen species production related with a decrease of the matrix metalloproteinase-9 activity and an increase of its expression was observed with NPs compared to free fucoidan. A proteomic analysis evidenced that some fucoidan regulated proteins appeared, which were related to protein synthesis, N-glycan processing, and cellular stress. To our knowledge, this is the first study which reveals such activity induced by fucoidan. These results pave the way for USPIO-fucoidan-NPs as potential theranostic nanotools for hepatocellular carcinoma treatment.

Assessment of the Morphological, Optical, and Photoluminescence Properties of HfO2 Nanoparticles Synthesized by a Sol-Gel Method Assisted by Microwave Irradiation.

In this work, we optimized the synthesis of HfO2 nanoparticles (NPs) with a nonaqueous sol-gel method assisted by microwave heating, with a direct surfactant-free extraction and stabilization in water. To tune the structural, morphological, and photophysical properties, we explored the influence of reaction time, heating temperature, and type and concentration of a salt precursor. The controlled size, shape, crystallinity associated with high stability, a good yield of production, and stabilization in water without any surfactant modification of these HfO2 NPs open possibilities for future optoelectronic and biomedical applications. The investigation of their optical properties, revealed a high absorption in the UV range and the presence of a large band gap, originating in transparency at visible wavelengths. Under UV excitation, photoluminescence (PL) shows three emission bands centered at 305, 381, and 522 nm and are assigned to the vibronic transition of an excited OH•* radical or to a self-trapped exciton, to threefold oxygen vacancies VO3 with recombination to the valence band, and to defect level, respectively. The presence of oxygen vacancies associated with PL properties is particularly attractive for optoelectronic, photocatalysis, scintillator, and UV photosensor applications. Finally, by changing the nature of the hafnium precursor salt, using hafnium ethoxide or hafnium acetylacetonate, low-crystallized and aggregated NPs were obtained, which requires further investigation.

Biosynthesis of magnetic nanoparticles from nano-degradation products revealed in human stem cells.

While magnetic nanoparticles offer exciting possibilities for stem cell imaging or tissue bioengineering, their long-term intracellular fate remains to be fully documented. Besides, it appears that magnetic nanoparticles can occur naturally in human cells, but their origin and potentially endogenous synthesis still need further understanding. In an effort to explore the life cycle of magnetic nanoparticles, we investigated their transformations upon internalization in mesenchymal stem cells and as a function of the cells' differentiation status (undifferentiated, or undergoing adipogenesis, osteogenesis, and chondrogenesis). Using magnetism as a fingerprint of the transformation process, we evidenced an important degradation of the nanoparticles during chondrogenesis. For the other pathways, stem cells were remarkably "remagnetized" after degradation of nanoparticles. This remagnetization phenomenon is the direct demonstration of a possible neosynthesis of magnetic nanoparticles in cellulo and could lay some foundation to understand the presence of magnetic crystals in human cells. The neosynthesis was shown to take place within the endosomes and to involve the H-subunit of ferritin. Moreover, it appeared to be the key process to avoid long-term cytotoxicity (impact on differentiation) related to high doses of magnetic nanoparticles within stem cells.

A Preclinical Validation of Iron Oxide Nanoparticles for Treatment of Perianal Fistulizing Crohn's Disease.

Fistulizing anoperineal lesions are severe complications of Crohn's disease (CD) that affect quality of life with a long-term risk of anal sphincter destruction, incontinence, permanent stoma, and anal cancer. Despite several surgical procedures, they relapse in about two-thirds of patients, mandating innovative treatments. Ultrasmall particles of iron oxide (USPIO) have been described to achieve in vivo rapid healing of deep wounds in the skin and liver of rats thanks to their nanobridging capability that could be adapted to fistula treatment. Our main purpose was to highlight preclinical data with USPIO for the treatment of perianal fistulizing CD. Twenty male Sprague Dawley rats with severe 2,4,6-trinitrobenzenesulfonic acid solution (TNBS)-induced proctitis were operated to generate two perianal fistulas per rat. At day 35, two inflammatory fistulas were obtained per rat and perineal magnetic resonance imaging (MRI) was performed. After a baseline MRI, a fistula tract was randomly drawn and topically treated either with saline or with USPIO for 1 min (n = 17 for each). The rats underwent a perineal MRI on postoperative days (POD) 1, 4, and 7 and were sacrificed for pathological examination. The primary outcome was the filling or closure of the fistula tract, including the external or internal openings. USPIO treatment allowed the closure and/or filling of all the treated fistulas from its application until POD 7 in comparison with the control fistulas (23%). The treatment with USPIO was safe, permanently closed the fistula along its entire length, including internal and external orifices, and paved new avenues for the treatment of perianal fistulizing Crohn's disease.

Ever-Evolving Identity of Magnetic Nanoparticles within Human Cells: The Interplay of Endosomal Confinement, Degradation, Storage, and Neocrystallization.

Considerable knowledge has been acquired in inorganic nanoparticles' synthesis and nanoparticles' potential use in biomedical applications. Among different materials, iron oxide nanoparticles remain unrivaled for several reasons. Not only do they respond to multiple physical stimuli (e.g., magnetism, light) and exert multifunctional therapeutic and diagnostic actions but also they are biocompatible and integrate endogenous iron-related metabolic pathways. With the aim to optimize the use of (magnetic) iron oxide nanoparticles in biomedicine, different biophysical phenomena have been recently identified and studied. Among them, the concept of a "nanoparticle's identity" is of particular importance. Nanoparticles' identities evolve in distinct biological environments and over different periods of time. In this Account, we focus on the remodeling of magnetic nanoparticles' identities following their journey inside cells. For instance, nanoparticles' functions, such as heat generation or magnetic resonance imaging, can be highly impacted by endosomal confinement. Structural degradation of nanoparticles was also evidenced and quantified in cellulo and correlates with the loss of magnetic nanoparticle properties. Remarkably, in human stem cells, the nonmagnetic products of nanoparticles' degradation could be subsequently reassembled into neosynthesized, endogenous magnetic nanoparticles. This stunning occurrence might account for the natural presence of magnetic particles in human organs, especially the brain. However, mechanistic details and the implication of such phenomena in homeostasis and disease have yet to be completely unraveled.This Account aims to assess the short- and long-term transformations of magnetic iron oxide nanoparticles in living cells, particularly focusing on human stem cells. Precisely, we herein overview the multiple and ever-evolving chemical, physical, and biological magnetic nanoparticles' identities and emphasize the remarkable intracellular fate of these nanoparticles.

Covalent Organic Framework Embedded with Magnetic Nanoparticles for MRI and Chemo-Thermotherapy.

Nanoscale imine-linked covalent organic frameworks (nCOFs) were first loaded with the anticancer drug Doxorubicin (Dox), coated with magnetic iron oxide nanoparticles (γ-Fe2O3 NPs), and stabilized with a shell of poly(l-lysine) cationic polymer (PLL) for simultaneous synergistic thermo-chemotherapy treatment and MRI imaging. The pH responsivity of the resulting nanoagents (γ-SD/PLL) allowed the release of the drug selectively within the acidic microenvironment of late endosomes and lysosomes of cancer cells (pH 5.4) and not in physiological conditions (pH 7.4). γ-SD/PLL could efficiently generate high heat (48 °C) upon exposure to an alternating magnetic field due to the nCOF porous structure that facilitates the heat conduction, making γ-SD/PLL excellent heat mediators in an aqueous solution. The drug-loaded magnetic nCOF composites were cytotoxic due to the synergistic toxicity of Dox and the effects of hyperthermia in vitro on glioblastoma U251-MG cells and in vivo on zebrafish embryos, but they were not significantly toxic to noncancerous cells (HEK293). To the best of our knowledge, this is the first report of multimodal MRI probe and chemo-thermotherapeutic magnetic nCOF composites.

Bimodal Fucoidan-Coated Zinc Oxide/Iron Oxide-Based Nanoparticles for the Imaging of Atherothrombosis.

A polyol method was used to obtain ultrasmall ZnO nanoparticles (NPs) doped with iron ions and coated with a low molecular weight fucoidan in order to perform in vivo MR and ex vivo fluorescence imaging of athrothrombosis. During the synthesis, the early elimination of water by azeotropic distillation with toluene allowed us to produce NPs which size, determined by XRD and TEM, decreased from 7 nm to 4 nm with the increase of iron/zinc ratios from 0.05 to 0.50 respectively. For the highest iron content (NP-0.50) NPs were evidenced as a mixture of nanocrystals made of wurtzite and cubic phase with a molar ratio of 2.57:1, although it was not possible to distinguish one from the other by TEM. NP-0.50 were superparamagnetic and exhibited a large emission spectrum at 470 nm when excited at 370 nm. After surface functionalization of NP-0.50 with fucoidan (fuco-0.50), the hydrodynamic size in the physiological medium was 162.0 ± 0.4 nm, with a corresponding negative zeta potential of -48.7 ± 0.4 mV, respectively. The coating was evidenced by FT-IR spectra and thermogravimetric analysis. Aqueous suspensions of fuco-0.50 revealed high transverse proton relaxivities (T2) with an r2 value of 173.5 mM-1 s-1 (300 K, 7.0 T) and remained stable for more than 3 months in water or in phosphate buffer saline without evolution of the hydrodynamic size and size distribution. No cytotoxic effect was observed on human endothelial cells up to 48 h with these NPs at a dose of 0.1 mg/mL. After injection into a rat model of atherothrombosis, MR imaging allowed the localization of diseased areas and the subsequent fluorescence imaging of thrombus on tissue slices.

Tolerogenic Iron Oxide Nanoparticles in Type 1 Diabetes: Biodistribution and Pharmacokinetics Studies in Nonobese Diabetic Mice.

Nanoparticle (NP) administration is among the most attractive approaches to exploit the synergy of different copackaged molecules for the same target. In this work, iron oxide NPs are surface-engineered for the copackaging of the autoantigen proinsulin, a major target of adaptive immunity in type 1 diabetes (T1D), and 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methylester (ITE), a small drug conditioning a tolerogenic environment. Magnetic resonance imaging (MRI) combined with magnetic quantification are used to investigate NP biokinetics in nonobese diabetic (NOD) mice and control mice in different organs. Different NP biodistribution, with in particular enhanced kidney elimination and a stronger accumulation in the pancreas for prediabetic NOD mice, is observed. This is related to preferential NP accumulation in the pancreatic inflammatory zone and to enhancement of renal elimination by diabetic nephropathy. For both mouse strains, an MRI T2 contrast enhancement at 72 h in the liver, pancreas, and kidneys, and indicating recirculating NPs, is also found. This unexpected result is confirmed by magnetic quantification at different time points as well as by histological evaluation. Besides, such NPs are potential MRI contrast agents for early diagnosis of T1D.

Nanohybrids with Magnetic and Persistent Luminescence Properties for Cell Labeling, Tracking, In Vivo Real-Time Imaging, and Magnetic Vectorization.

Once injected into a living organism, cells diffuse or migrate around the initial injection point and become impossible to be visualized and tracked in vivo. The present work concerns the development of a new technique for therapeutic cell labeling and subsequent in vivo visualization and magnetic retention. It is hypothesized and subsequently demonstrated that nanohybrids made of persistent luminescence nanoparticles and ultrasmall superparamagnetic iron oxide nanoparticles incorporated into a silica matrix can be used as an effective nanoplatform to label therapeutic cells in a nontoxic way in order to dynamically track them in real-time in vitro and in living mice. As a proof-of-concept, it is shown that once injected, these labeled cells can be visualized and attracted in vivo using a magnet. This first step suggests that these nanohybrids represent efficient multifunctional nanoprobes for further imaging guided cell therapies development.

Iron oxide nanoparticle surface decorated with cRGD peptides for magnetic resonance imaging of brain tumors.

In this article, a specific targeting Magnetic Resonance Imaging (MRI) nanoplatform, composed by iron oxide nanoparticle (NP) with cRGD peptides as targeting agent onto NP surface, is explored for the diagnosis of brain tumors by MRI using intracranial U87MG mice xenograft tumor. This article is part of a Special Issue entitled "Recent Advances in Bionanomaterials" Guest Editor: Dr. Marie-Louise Saboungi and Dr. Samuel D. Bader.

Tetrazine Click Chemistry for the Modification of 1-Hydroxy-1,1-methylenebisphosphonic Acids: Towards Bio-orthogonal Functionalization of Gold Nanoparticles.

Inverse electron demand Diels-Alder (iEDDA) was evaluated for the functionalization of gold nanoparticles. The reaction was first modelled with the free coating molecule 1-hydroxy-1,1-methylenebisphosphonate bearing an alkene functionality (HMBPene). A model tetrazine 3,6-dipyridin-2-yl-1,2,4,5-tetrazine (pyTz) was used, kinetic of the reaction was calculated and coupling products were analysed by NMR and HRMS. The reaction was then transposed at the nanoparticle surface. Gold nanoparticles bearing an alkene functionality were obtained using a one-pot methodology with HMBPene and the tetrazine click chemistry was evaluated at their surface using pyTz. The successful coupling was assessed by XPS measurements. This click-methodology was extended to the conjugation of a NIR probe at the NP surface.

Design, Properties, and In Vivo Behavior of Super-paramagnetic Persistent Luminescence Nanohybrids.

With the fast development of noninvasive diagnosis, the design of multimodal imaging probes has become a promising challenge. If many monofunctional nanocarriers have already proven their efficiency, only few multifunctional nanoprobes have been able to combine the advantages of diverse imaging modalities. An innovative nanoprobe called mesoporous persistent luminescence magnetic nanohybrids (MPNHs) is described that shows both optical and magnetic resonance imaging (MRI) properties intended for in vivo multimodal imaging in small animals. MPNHs are based on the assembly of chromium-doped zinc gallate oxide and ultrasmall superparamagnetic iron oxide nanoparticles embedded in a mesoporous silica shell. MPNHs combine the optical advantages of persistent luminescence, such as real time imaging with highly sensitive and photostable detection, and MRI negative contrast properties that ensure in vivo imaging with rather high spatial resolution. In addition to their imaging capabilities, these MPNHs can be motioned in vitro with a magnet, which opens multiple perspectives in magnetic vectorization and cell therapy research.

Non-aqueous sol-gel synthesis of ultra small persistent luminescence nanoparticles for near-infrared in vivo imaging.

Ultra-small ZnGa2 O4 :Cr(3+) nanoparticles (6 nm) that exhibit near-infrared (NIR) persistent luminescence properties are synthesized by using a non-aqueous sol-gel method assisted by microwave irradiation. The nanoparticles are pegylated, leading to highly stable dispersions under physiological conditions. Preliminary in vivo studies show the high potential for these ultra-small ZnGa2 O4 :Cr(3+) nanoparticles to be used as in vivo optical nanotools as they emit without the need for in situ excitation and, thus, avoid the autofluorescence of tissues.

Viologen-templated arrays of cucurbit[7]uril-modified iron-oxide nanoparticles.

Magnetic and fluorescent assemblies of iron-oxide nanoparticles (NPs) were constructed by threading a viologen-based ditopic ligand, DPV(2+), into the cavity of cucurbituril (CB[7]) macrocycles adsorbed on the surface of the NPs. Evidence for the formation of 1:2 inclusion complexes that involve DPV(2+) and two CB[7] macrocycles was first obtained in solution by (1)H NMR and emission spectroscopy. DPV(2+) was found to induce self-assembly of nanoparticle arrays (DPV(2+)⊂CB[7]NPs) by bridging CB[7] molecules on different NPs. The resulting viologen-crosslinked iron-oxide nanoparticles exhibited increased saturation magnetization and emission properties. This facile supramolecular approach to NP self-assembly provides a platform for the synthesis of smart and innovative materials that can achieve a high degree of functionality and complexity and that are needed for a wide range of applications.

The Prognosis of Glutamic Acid Decarboxylase Antibodies in Women With Hyperglycemia in Pregnancy.

CONTEXT: We recently reported that the presence of glutamic acid decarboxylase antibodies (GADA) was not associated with large-for-gestational-age infants in women with hyperglycemia in pregnancy (HIP). OBJECTIVE: We explored the association between the presence of GADA and other HIP-related adverse pregnancy outcomes. METHODS: This observational prospective study, conducted at a university hospital in a suburb of Paris, France, included 1182 consecutive women with HIP measured for GADA at HIP care initiation between 2012 and 2017. Post hoc analyses for outcomes included gestational weight gain, insulin therapy, cesarean delivery, hypertensive disorders, small-for-gestational-age infant, prematurity, and neonatal hypoglycemia. RESULTS: Of the 1182 women studied, 87 (7.4%) had positive (≥ 1 IU/mL) GADA. Although socioeconomic, clinical, and biological characteristics were similar across women in the positive and negative GADA groups, higher fasting plasma glucose values during early HIP screening were observed in the former (5.5 ± 1.5 vs 5.2 ± 0.7 mmol/L respectively, P < .001). At HIP care initiation, fructosamine levels were higher in women with positive GADA (208 ± 23 vs 200 ± 18 µmol/L; P < .05). In the homeostatic model assessment, insulin resistance (HOMA-IR) and beta secretion (HOMA-B) rates were similar in both groups. Gestational weight gain and the rates of all adverse outcomes were similar in both groups except for cesarean delivery (18.4 and 27.3% for positive and negative GADA, respectively; adjusted odds ratio 0.49 [95% CI, 0.26-0.92], P = .026). CONCLUSION: Universal measurement of GADA in women with HIP highlighted that 7.4% had positive GADA. No association was observed between GADA and HIP-related adverse pregnancy outcomes, except a lower risk of cesarean delivery.

Carbodiimide versus click chemistry for nanoparticle surface functionalization: a comparative study for the elaboration of multimodal superparamagnetic nanoparticles targeting αvß3 integrins.

Superparamagnetic fluorescent nanoparticles targeting αvß3 integrins were elaborated using two methodologies: carbodiimide coupling and click chemistries (CuACC and thiol-yne). The nanoparticles are first functionalized with hydroxymethylenebisphonates (HMBP) bearing carboxylic acid or alkyne functions. Then, a large number of these reactives functions were used for the covalent coupling of dyes, poly(ethylene glycol) (PEG), and cyclic RGD. Several methods were used to characterize the nanoparticle surface functionalization, and the magnetic properties of these contrast agents were studied using a 1.5 T clinical MRI. The affinity toward integrins was evidenced by solid-phase receptor-binding assay. In addition to their chemoselective natures, click reactions were shown to be far more efficient than the carbodiimide coupling. The grafting increase was shown to enhance targeting affinity to integrin without imparing MRI and fluorescent properties.

Photothermia at the nanoscale induces ferroptosis via nanoparticle degradation.

The Fe(II)-induced ferroptotic cell death pathway is an asset in cancer therapy, yet it calls into question the biocompatibility of magnetic nanoparticles. In the latter, Fe(II) is sequestered within the crystal structure and is released only upon nanoparticle degradation, a transition that is not well understood. Here, we dissect the chemical environment necessary for nanoparticle degradation and subsequent Fe(II) release. Importantly, temperature acts as an accelerator of the process and can be triggered remotely by laser-mediated photothermal conversion, as evidenced by the loss of the nanoparticles' magnetic fingerprint. Remarkably, the local hot-spot temperature generated at the nanoscale can be measured in operando, in the vicinity of each nanoparticle, by comparing the photothermal-induced nanoparticle degradation patterns with those of global heating. Further, remote photothermal irradiation accelerates degradation inside cancer cells in a tumor spheroid model, with efficiency correlating with the endocytosis progression state of the nanoparticles. High-throughput imaging quantification of Fe2+ release, ROS generation, lipid peroxidation and cell death at the spheroid level confirm the synergistic thermo-ferroptotic therapy due to the photothermal degradation at the nanoparticle level.

REVIEW: "ISCHEMIC STROKE: From Fibrinolysis to Functional Recovery" Nanomedicine: Emerging Approaches to Treat Ischemic Stroke.

Stroke is responsible for 11% of all deaths worldwide, the majority of which are caused by ischemic strokes, thus making the need to urgently find safe and effective therapies. Today, these can be cured either by mechanical thrombectomy when the thrombus is accessible, or by intravenous injection of fibrinolytics. However, the latter present several limitations, such as potential severe side effects, few eligible patients and low rate of partial and full recovery. To design safer and more effective treatments, nanomedicine appeared in this medical field a few decades ago. This review will explain why nanoparticle-based therapies and imaging techniques are relevant for ischemic stroke management. Then, it will present the different nanoparticle types that have been recently developed to treat this pathology. It will also study the various targeting strategies used to bring nanoparticles to the stroke site, thereby limiting side effects and improving the therapeutic efficacy. Finally, this review will present the few clinical studies testing nanomedicine on stroke and discuss potential causes for their scarcity.

Biomineralization of magnetic nanoparticles in stem cells.

Iron is one of the most common metals in the human body, with an intrinsic metabolism including proteins involved in its transport, storage, and redox mechanisms. A less explored singularity is the presence of magnetic iron in the organism, especially in the brain. The capacity of human stem cells to biosynthesize magnetic nanoparticles was recently demonstrated, using iron released by the degradation of synthetic magnetic nanoparticles. To evidence a magnetic biomineralization in mammalian cells, it is required to address the biosynthesis of magnetic nanoparticles in cells supplied exclusively with non-magnetic iron salt precursors. Herein, mouse and human mesenchymal stem cells were incubated with ferric quinate for up to 36 days. By optimizing the concentration and culture time, and by measuring both total intracellular iron content and cellular magnetic signals, the biosynthesis of magnetic nanoparticles was found to occur from 14 days of continuous iron incubation and was correlated with important doses of intracellular iron. The local electronic structure and chemical environment of intracellular iron were further characterized by XAS spectroscopy at the Fe K-edge, showing a total conversion of Fe2+ to Fe3+ when using ferrous salts (ascorbate and sulfate), and a transformation towards ferrihydrite as well as a small proportion of a magnetic phase.