Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 20
Filter
Add more filters










Publication year range
1.
Nanomaterials (Basel) ; 10(9)2020 Aug 24.
Article in English | MEDLINE | ID: mdl-32847105

ABSTRACT

We present a 1H Nuclear Magnetic Resonance (NMR) relaxometry experimental investigation of two series of magnetic nanoparticles, constituted of a maghemite core with a mean diameter dTEM = 17 ± 2.5 nm and 8 ± 0.4 nm, respectively, and coated with four different negative polyelectrolytes. A full structural, morpho-dimensional and magnetic characterization was performed by means of Transmission Electron Microscopy, Atomic Force Microscopy and DC magnetometry. The magnetization curves showed that the investigated nanoparticles displayed a different approach to the saturation depending on the coatings, the less steep ones being those of the two samples coated with P(MAA-stat-MAPEG), suggesting the possibility of slightly different local magnetic disorders induced by the presence of the various polyelectrolytes on the particles' surface. For each series, 1H NMR relaxivities were found to depend very slightly on the surface coating. We observed a higher transverse nuclear relaxivity, r2, at all investigated frequencies (10 kHz ≤ νL ≤ 60 MHz) for the larger diameter series, and a very different frequency behavior for the longitudinal nuclear relaxivity, r1, between the two series. In particular, the first one (dTEM = 17 nm) displayed an anomalous increase of r1 toward the lowest frequencies, possibly due to high magnetic anisotropy together with spin disorder effects. The other series (dTEM = 8 nm) displayed a r1 vs. νL behavior that can be described by the Roch's heuristic model. The fitting procedure provided the distance of the minimum approach and the value of the Néel reversal time (τ ≈ 3.5 ÷ 3.9·10-9 s) at room temperature, confirming the superparamagnetic nature of these compounds.

2.
Nanomaterials (Basel) ; 10(1)2019 Dec 20.
Article in English | MEDLINE | ID: mdl-31861876

ABSTRACT

Nanoassemblies encompass a large variety of systems (organic, crystalline, amorphous and porous). The nanometric size enables these systems to interact with biological entities and cellular organelles of similar dimensions (proteins, cells, …). Over the past 20 years, the exploitation of their singular properties as contrast agents has led to the improvement of medical imaging. The use of nanoprobes also allows the combination of several active units within the same nanostructure, paving the way to multi-imaging. Thus, the nano-object provides various additional information which helps simplify the number of clinical procedures required. In this review, we are interested in the combination between fluorescent units and magnetic nanoparticles to perform dual-mode magnetic resonance imaging (MRI) and fluorescent imaging. The effect of magnetic interaction in multicore iron oxide nanoparticles on the MRI contrast agent properties is highlighted.

3.
J Nanosci Nanotechnol ; 19(8): 5000-5007, 2019 08 01.
Article in English | MEDLINE | ID: mdl-30913813

ABSTRACT

Water dispersible cobalt ferrite nanoparticles, CoxFe3-xO4, of different size (4-10 nm) and various composition (0 ≤ x ≤ 1), functionalized with a rhamnose derivative were obtained and characterized by combining TEM, XRD and elemental analyses techniques. Magnetic properties of these systems were studied by SQUID magnetometry. A particular emphasis was given to the investigation of magnetocrystalline anisotropy and size effect on the heating abilities of the nanoparticles under the application of an alternating magnetic field.

4.
Small ; 14(38): e1802307, 2018 09.
Article in English | MEDLINE | ID: mdl-30146711

ABSTRACT

Bright supramolecular fluorescent organic nanoassemblies (FONs), based on strongly polar red-emissive benzothiadiazole fluorophores containing acidic units, are fabricated to serve as theranostic tools with large colloidal stability in the absence of a polymer or surfactant. High architectural cohesion is ensured by the multiple hydrogen-bonding networks, reinforced by the dipolar and hydrophobic interactions developed between the dyes. Such interactions are harnessed to ensure high payload encapsulation and efficient trapping of hydrophobic and hydrogen-bonding drugs like doxorubicin, as shown by steady state and time-resolved measurements. Fine tuning of the drug release in cancer cells is achieved by adjusting the structure and combination of the fluorophore acidic units. Notably delayed drug delivery is observed by confocal microscopy compared to the entrance of hydrosoluble doxorubicin, demonstrating the absence of undesirable burst release outside the cells by using FONs. Since FON-constituting fluorophores exhibit a large emission shift from red to green when dissociating in contact with the lipid cellular content, drug delivery could advantageously be followed by dual-color spectral detection, independently of the drug staining potentiality.


Subject(s)
Doxorubicin/chemistry , Drug Delivery Systems/methods , Nanoparticles/chemistry , Polymers/chemistry , Hydrogen Bonding , Microscopy, Confocal
5.
Nanoscale ; 9(45): 18094-18106, 2017 Nov 23.
Article in English | MEDLINE | ID: mdl-29135000

ABSTRACT

The field of optical bioimaging has considerably flourished with the advent of sophisticated microscopy techniques and ultra-bright fluorescent tools. Fluorescent organic nanoparticles (FONs) have thus recently appeared as very attractive labels for their high payload, absence of cytotoxicity and eventual biodegradation. Nevertheless, their bioconjugation to target specific receptors with high imaging contrast is scarcely performed. Moreover, assessing the reality of bioconjugation represents high challenges given the sub-nanomolar concentrations resulting from the commonly adopted nanoprecipitation fabrication process. Here, we describe how the combination of a magnetic shell allows us to easily generate red-emitting FONs conjugated with the epidermal growth factor ligand (EGF), a small protein promoting cancer cell proliferation by activating the EGF receptor (EGFR) pathway. Dual color fluorescence correlation spectroscopy combined with immunofluorescence is originally harnessed in its time trace mode to unambiguously demonstrate covalent attachment between the FON and EGF at sub-nanomolar concentrations. Strong asymmetric clustering of EGF-conjugated FONs is observed at the membrane of MDA-MB-468 human breast cancer cells overexpressing EGF receptors using super-resolution fluorescence microscopy. Such high recruitment of EGF-conjugated FONs is attributed to their EGF multivalency (4.7 EGF per FON) which enables efficient EGFR activation and subsequent phosphorylation. The large hydrodynamic diameter (DH ∼ 301 nm) of EGF-conjugated FONs prevents immediate engulfment of the sequestered receptors, which provides very bright and localized spots in less than 30 minutes. The reported bioconjugated nanoassemblies could thus serve as ultra-bright probes of breast cancer cells with EGFR-overexpression that is often associated with poor prognosis.


Subject(s)
Breast Neoplasms/metabolism , Nanoconjugates/chemistry , Nanoparticles/chemistry , Cell Line, Tumor , Cell Proliferation , Epidermal Growth Factor , ErbB Receptors/metabolism , Fluorescence , Humans
6.
ACS Appl Mater Interfaces ; 9(16): 14242-14257, 2017 Apr 26.
Article in English | MEDLINE | ID: mdl-28379690

ABSTRACT

Controlling the interactions of functional nanostructures with water and biological media represents high challenges in the field of bioimaging applications. Large contrast at low doses, high colloidal stability in physiological conditions, the absence of cell cytotoxicity, and efficient cell internalization represent strong additional needs. To achieve such requirements, we report on high-payload magnetofluorescent architectures made of a shell of superparamagnetic iron oxide nanoparticles tightly anchored around fluorescent organic nanoparticles. Their external coating is simply modulated using anionic polyelectrolytes in a final step to provide efficient magnetic resonance imaging (MRI) and fluorescence imaging of live cells. Various structures of PEGylated polyelectrolytes have been synthesized and investigated, differing from their iron oxide complexing units (carboxylic vs phosphonic acid), their structure (block- or comblike), their hydrophobicity, and their fabrication process [conventional or reversible addition-fragmentation chain transfer (RAFT)-controlled radical polymerization] while keeping the central magnetofluorescent platforms the same. Combined photophysical, magnetic, NMRD, and structural investigations proved the superiority of RAFT polymer coatings containing carboxylate units and a hydrophobic tail to impart the magnetic nanoassemblies (NAs) with enhanced-MRI negative contrast, characterized by a high r2/r1 ratio and a transverse relaxation r2 equal to 21 and 125 s-1 mmol-1 L, respectively, at 60 MHz clinical frequency (∼1.5 T). Thanks to their dual modality, cell internalization of the NAs in mesothelioma cancer cells could be evidenced by both confocal fluorescence microscopy and magnetophoresis. A 72 h follow-up showed efficient uptake after 24 h with no notable cell mortality. These studies again pointed out the distinct behavior of RAFT polyelectrolyte-coated bimodal NAs that internalize at a slower rate with no adverse cytotoxicity. Extension to multicellular tumor cell spheroids that mimic solid tumors revealed the successful internalization of the NAs in the periphery cells, which provides efficient deep-imaging labels thanks to their induced T2* contrast, large emission Stokes shift, and bright dotlike signal, popping out of the strong spheroid autofluorescence.


Subject(s)
Contrast Media/chemistry , Anions , Humans , Magnetic Resonance Imaging , Nanoparticles , Neoplasms , Polyethylene Glycols
7.
J Colloid Interface Sci ; 479: 139-149, 2016 Oct 01.
Article in English | MEDLINE | ID: mdl-27388127

ABSTRACT

High-density nanoarchitectures, endowed with simultaneous fluorescence and contrast properties for MRI and TEM imaging, have been obtained using a simple self-assembling strategy based on supramolecular interactions between non-doped fluorescent organic nanoparticles (FON) and superparamagnetic nanoparticles. In this way, a high-payload core-shell structure FON@mag has been obtained, protecting the hydrophobic fluorophores from the surroundings as well as from emission quenching by the shell of magnetic nanoparticles. Compared to isolated nanoparticles, maghemite nanoparticles self-assembled as an external shell create large inhomogeneous magnetic field, which causes enhanced transverse relaxivity and exacerbated MRI contrast. The magnetic load of the resulting nanoassemblies is evaluated using magnetic sedimentation and more originally electrospray mass spectrometry. The role of the stabilizing agents (citrate versus polyacrylate anions) revealed to be crucial regarding the cohesion of the resulting high-performance magneto-fluorescent nanoassemblies, which questions their use after cell internalization as nanocarriers or imaging agents for reliable correlative light and electron microcopy.


Subject(s)
Contrast Media/chemistry , Fluorescent Dyes/chemistry , Magnetite Nanoparticles/chemistry , Neoplasms/pathology , Humans , Magnetic Resonance Imaging , Molecular Structure , Particle Size , Surface Properties , Tumor Cells, Cultured
8.
ACS Nano ; 9(8): 7925-39, 2015 Aug 25.
Article in English | MEDLINE | ID: mdl-26168364

ABSTRACT

Safe implementation of nanotechnology and nanomedicine requires an in-depth understanding of the life cycle of nanoparticles in the body. Here, we investigate the long-term fate of gold/iron oxide heterostructures after intravenous injection in mice. We show these heterostructures degrade in vivo and that the magnetic and optical properties change during the degradation process. These particles eventually eliminate from the body. The comparison of two different coating shells for heterostructures, amphiphilic polymer or polyethylene glycol, reveals the long lasting impact of initial surface properties on the nanocrystal degradability and on the kinetics of elimination of magnetic iron and gold from liver and spleen. Modulation of nanoparticles reactivity to the biological environment by the choice of materials and surface functionalization may provide new directions in the design of multifunctional nanomedicines with predictable fate.


Subject(s)
Aging/physiology , Coated Materials, Biocompatible/pharmacokinetics , Drug Carriers/pharmacokinetics , Ferric Compounds/pharmacokinetics , Gold/pharmacokinetics , Magnetite Nanoparticles/analysis , Alkenes/chemistry , Animals , Coated Materials, Biocompatible/chemistry , Drug Carriers/chemistry , Ferric Compounds/chemistry , Gold/chemistry , Injections, Intravenous , Liver/metabolism , Liver/ultrastructure , Magnetite Nanoparticles/chemistry , Magnetite Nanoparticles/ultrastructure , Maleic Anhydrides/chemistry , Mice , Mice, Inbred C57BL , Nanomedicine/instrumentation , Nanomedicine/methods , Polyethylene Glycols/chemistry , Polymers/chemistry , Spleen/metabolism , Spleen/ultrastructure , Static Electricity , Surface Properties
9.
Biol Aujourdhui ; 208(2): 177-90, 2014.
Article in French | MEDLINE | ID: mdl-25190577

ABSTRACT

The use of nanomaterials drastically increases and yet their behavior in living organisms remains poorly examined. At the same time a better comprehension of the interactions between nanoparticles and the biological environment would allow us to limit potential nanoparticle-based toxicity and fully exploit nanoparticles medical applications. In this perspective, it is high time we develop methods to detect, quantify and follow the evolution of nanoparticles in the complex biological environment, spanning all relevant scales from the nanometer up to the tissue level. In this work we follow the life cycle of magnetic nanoparticles in vivo, focusing on their transformations over time from administration to elimination. As opposed to traditional nano-toxicological approaches, we herein take the nanoparticle perspective and try to establish how biological environment might impact the particles properties and their fate (interaction with proteins, cell confinement, degradation...) from their initial state to a series of changes a nanoparticle might undergo on its journey throughout the organism.


Subject(s)
Magnetite Nanoparticles , Animals , Biological Transport , Blood Proteins/drug effects , Blood Proteins/metabolism , Endocytosis/physiology , Humans , Inactivation, Metabolic , Magnetite Nanoparticles/chemistry , Magnetite Nanoparticles/toxicity , Tissue Distribution
10.
Biomaterials ; 35(24): 6400-11, 2014 Aug.
Article in English | MEDLINE | ID: mdl-24816363

ABSTRACT

Magnetic hyperthermia mediated by magnetic nanomaterials is one promising antitumoral nanotherapy, particularly for its ability to remotely destroy deep tumors. More and more new nanomaterials are being developed for this purpose, with improved heat-generating properties in solution. However, although the ultimate target of these treatments is the tumor cell, the heating efficiency, and the underlying mechanisms, are rarely studied in the cellular environment. Here we attempt to fill this gap by making systematic measurements of both hyperthermia and magnetism in controlled cell environments, using a wide range of nanomaterials. In particular, we report a systematic fall in the heating efficiency for nanomaterials associated with tumour cells. Real-time measurements showed that this loss of heat-generating power occurred very rapidly, within a matter of minutes. The fall in heating correlated with the magnetic characterization of the samples, demonstrating a complete inhibition of the Brownian relaxation in cellular conditions.


Subject(s)
Cellular Microenvironment , Hyperthermia, Induced , Magnetic Phenomena , Nanoparticles/chemistry , Nanotechnology , Anisotropy , Cell Line, Tumor , Cell Survival , Hot Temperature , Humans , Nanoparticles/ultrastructure , Solutions , Spectrophotometry, Atomic
11.
Small ; 10(16): 3325-37, 2014 Aug 27.
Article in English | MEDLINE | ID: mdl-24797733

ABSTRACT

Understanding the relation between the structure and the reactivity of nanomaterials in the organism is a crucial step towards efficient and safe biomedical applications. The multi-scale approach reported here, allows following the magnetic and structural transformations of multicore maghemite nanoflowers in a medium mimicking intracellular lysosomal environment. By confronting atomic-scale and macroscopic information on the biodegradation of these complex nanostuctures, we can unravel the mechanisms involved in the critical alterations of their hyperthermic power and their Magnetic Resonance imaging T1 and T2 contrast effect. This transformation of multicore nanoparticles with outstanding magnetic properties into poorly magnetic single core clusters highlights the harmful influence of cellular medium on the therapeutic and diagnosis effectiveness of iron oxide-based nanomaterials. As biodegradation occurs through surface reactivity mechanism, we demonstrate that the inert activity of gold nanoshells can be exploited to protect iron oxide nanostructures. Such inorganic nanoshields could be a relevant strategy to modulate the degradability and ultimately the long term fate of nanomaterials in the organism.


Subject(s)
Biodegradation, Environmental , Ferric Compounds/chemistry , Gold/chemistry , Nanostructures , Magnetic Resonance Imaging , Microscopy, Electron, Transmission
12.
ACS Nano ; 8(5): 4268-83, 2014 May 27.
Article in English | MEDLINE | ID: mdl-24738788

ABSTRACT

Several studies propose nanoparticles for tumor treatment, yet little is known about the fate of nanoparticles and intimate interactions with the heterogeneous and ever-evolving tumor environment. The latter, rich in extracellular matrix, is responsible for poor penetration of therapeutics and represents a paramount issue in cancer therapy. Hence new strategies start aiming to modulate the neoplastic stroma. From this perspective, we assessed the efficacy of 19 nm PEG-coated iron oxide nanocubes with optimized magnetic properties to mediate mild tumor magnetic hyperthermia treatment. After injection of a low dose of nanocubes (700 µg of iron) into epidermoid carcinoma xenografts in mice, we monitored the effect of heating nanocubes on tumor environment. In comparison with the long-term fate after intravenous administration, we investigated spatiotemporal patterns of nanocube distribution, evaluated the evolution of cubes magnetic properties, and examined nanoparticle clearance and degradation processes. While inside tumors nanocubes retained their magnetic properties and heating capacity throughout the treatment due to a mainly interstitial extracellular location, the particles became inefficient heaters after cell internalization and transfer to spleen and liver. Our multiscale analysis reveals that collagen-rich tumor extracellular matrix confines the majority of nanocubes. However, nanocube-mediated hyperthermia has the potential to "destructure" this matrix and improve nanoparticle and drug penetration into neoplastic tissue. This study provides insight into dynamic interactions between nanoparticles and tumor components under physical stimulation and suggests that nanoparticle-mediated hyperthermia could be used to locally modify tumor stroma and thus improve drug penetration.


Subject(s)
Ferric Compounds/chemistry , Metal Nanoparticles/chemistry , Neoplasms/pathology , Tumor Microenvironment , Animals , Cell Line, Tumor , Collagen/chemistry , Electron Spin Resonance Spectroscopy , Extracellular Matrix/metabolism , Female , Hot Temperature , Humans , Liver/drug effects , Liver/metabolism , Magnetic Resonance Imaging , Magnetics , Mice , Mice, Inbred C57BL , Mice, Nude , Microscopy, Electron, Transmission , Nanomedicine/methods , Nanoparticles/chemistry , Neoplasms/metabolism , Polyethylene Glycols/chemistry , Spleen/drug effects , Spleen/metabolism
13.
ACS Nano ; 7(5): 3939-52, 2013 May 28.
Article in English | MEDLINE | ID: mdl-23634880

ABSTRACT

The long-term fate of nanomaterials in biological environment represents a critical matter, which determines environmental effects and potential risks for human health. Predicting these risks requires understanding of nanoparticle transformations, persistence, and degradation, some issues somehow ignored so far. Safe by design, inorganic nanostructures are being envisioned for therapy, yet fundamental principles of their processing in biological systems, change in physical properties, and in situ degradability have not been thoroughly assessed. Here we report the longitudinal visualization of iron oxide nanocube transformations inflicted by the intracellular-like environment. Structural degradation of individual nanocubes with two different surface coatings (amphiphilic polymer shell and polyethylene glycol ligand molecules) was monitored at the atomic scale with aberration-corrected high-resolution transmission electron microscopy. Our results suggest that the polymer coating controls surface reactivity and that availability and access of chelating agents to the crystal surface govern the degradation rate. This in situ study of single nanocube degradation was compared to intracellular transformations observed in mice over 14 days after intravenous injection, revealing the role of nanoparticle clustering, intracellular sorting within degradation compartments, and iron transfer and recycling into ferritin storage proteins. Our approach reduces the gap between in situ nanoscale observations in mimicking biological environments and in vivo real tracking of nanoparticle fate.


Subject(s)
Ferric Compounds/chemistry , Ferric Compounds/metabolism , Nanostructures , Animals , Biomimetic Materials/metabolism , Biotransformation , Humans , Kinetics , Liver/cytology , Lysosomes/metabolism , Mice , Microscopy, Electron, Transmission , Spleen/cytology , Surface Properties
14.
Adv Healthc Mater ; 2(2): 313-25, 2013 Feb.
Article in English | MEDLINE | ID: mdl-23184893

ABSTRACT

The labeling of stem cells with iron oxide nanoparticles is increasingly used to enable MRI cell tracking and magnetic cell manipulation, stimulating the fields of tissue engineering and cell therapy. However, the impact of magnetic labeling on stem-cell differentiation is still controversial. One compromising factor for successful differentiation may arise from early interactions of nanoparticles with cells during the labeling procedure. It is hypothesized that the lack of control over nanoparticle colloidal stability in biological media may lead to undesirable nanoparticle localization, overestimation of cellular uptake, misleading MRI cell tracking, and further impairment of differentiation. Herein a method is described for labeling mesenchymal stem cells (MSC), in which the physical state of citrate-coated nanoparticles (dispersed versus aggregated) can be kinetically tuned through electrostatic and magnetic triggers, as monitored by diffusion light scattering in the extracellular medium and by optical and electronic microscopy in cells. A set of statistical cell-by-cell measurements (flow cytometry, single-cell magnetophoresis, and high-resolution MRI cellular detection) is used to independently quantify the nanoparticle cell uptake and the effects of nanoparticle aggregation. Such aggregation confounds MRI cell detection as well as global iron quantification and has adverse effects on chondrogenetic differentiation. Magnetic labeling conditions with perfectly stable nanoparticles-suitable for obtaining differentiation-capable magnetic stem cells for use in cell therapy-are subsequently identified.


Subject(s)
Cell Tracking/methods , Magnetic Phenomena , Magnetite Nanoparticles , Mesenchymal Stem Cells/cytology , Cell Differentiation/physiology , Endocytosis/physiology , Flow Cytometry , High-Throughput Screening Assays , Humans , Magnetic Resonance Imaging , Magnetite Nanoparticles/ultrastructure , Microscopy, Electron, Transmission , Real-Time Polymerase Chain Reaction
15.
ACS Nano ; 6(12): 10935-49, 2012 Dec 21.
Article in English | MEDLINE | ID: mdl-23167525

ABSTRACT

In the pursuit of optimized magnetic nanostructures for diagnostic and therapeutic applications, the role of nanoparticle architecture has been poorly investigated. In this study, we demonstrate that the internal collective organization of multi-core iron oxide nanoparticles can modulate their magnetic properties in such a way as to critically enhance their hyperthermic efficiency and their MRI T(1) and T(2) contrast effect. Multi-core nanoparticles composed of maghemite cores were synthesized through a polyol approach, and subsequent electrostatic colloidal sorting was used to fractionate the suspensions by size and hence magnetic properties. We obtained stable suspensions of citrate-stabilized nanostructures ranging from single-core 10 nm nanoparticles to multi-core magnetically cooperative 30 nm nanoparticles. Three-dimensional oriented attachment of primary cores results in enhanced magnetic susceptibility and decreased surface disorder compared to individual cores, while preserving a superparamagnetic-like behavior of the multi-core structures and potentiating thermal losses. Exchange coupling in the multi-core nanoparticles modifies the dynamics of the magnetic moment in such a way that both the longitudinal and transverse NMR relaxivities are also enhanced. Long-term MRI detection of tumor cells and their efficient destruction by magnetic hyperthermia can be achieved thanks to a facile and nontoxic cell uptake of these iron oxide nanostructures. This study proves for the first time that cooperative magnetic behavior within highly crystalline iron oxide superparamagnetic multi-core nanoparticles can improve simultaneously therapeutic and diagnosis effectiveness over existing nanostructures, while preserving biocompatibility.


Subject(s)
Ferric Compounds/therapeutic use , Hyperthermia, Induced/methods , Magnetic Resonance Imaging/methods , Nanoparticles/therapeutic use , Citric Acid/chemistry , Contrast Media/chemistry , Contrast Media/therapeutic use , Ferric Compounds/chemistry , Humans , MCF-7 Cells , Magnetic Phenomena , Nanoparticles/chemistry , Particle Size , Static Electricity
16.
ACS Nano ; 6(4): 3080-91, 2012 Apr 24.
Article in English | MEDLINE | ID: mdl-22494015

ABSTRACT

Iron oxide nanocrystals (IONCs) are appealing heat mediator nanoprobes in magnetic-mediated hyperthermia for cancer treatment. Here, specific absorption rate (SAR) values are reported for cube-shaped water-soluble IONCs prepared by a one-pot synthesis approach in a size range between 13 and 40 nm. The SAR values were determined as a function of frequency and magnetic field applied, also spanning technical conditions which are considered biomedically safe for patients. Among the different sizes tested, IONCs with an average diameter of 19 ± 3 nm had significant SAR values in clinical conditions and reached SAR values up to 2452 W/g(Fe) at 520 kHz and 29 kAm(-1), which is one of the highest values so far reported for IONCs. In vitro trials carried out on KB cancer cells treated with IONCs of 19 nm have shown efficient hyperthermia performance, with cell mortality of about 50% recorded when an equilibrium temperature of 43 °C was reached after 1 h of treatment.


Subject(s)
Ferric Compounds/chemistry , Ferric Compounds/therapeutic use , Hyperthermia, Induced/methods , Nanostructures/chemistry , Nanostructures/therapeutic use , Neoplasms/pathology , Water/chemistry , Absorption , Cell Survival , Ferric Compounds/adverse effects , Humans , KB Cells , Magnetic Phenomena , Nanostructures/adverse effects , Nanotechnology , Neoplasms/therapy , Safety , Solubility , Temperature
17.
ACS Nano ; 6(3): 2665-78, 2012 Mar 27.
Article in English | MEDLINE | ID: mdl-22324868

ABSTRACT

One of the first biointeractions of magnetic nanoparticles with living systems is characterized by nanoparticle-protein complex formation. The proteins dynamically encompass the particles in the protein corona. Here we propose a method based on nanomagnetism that allows a specific in situ monitoring of interactions between iron oxide nanoparticles and blood plasma. Tracking the nanoparticle orientation through their optical birefringence signal induced by an external magnetic field provides a quantitative real-time detection of protein corona at the surface of nanoparticles and assesses eventual onset of particle aggregation. Since some of the plasma proteins may cause particle aggregation, we use magnetic fractionation to separate the nanoparticle clusters (induced by "destabilizing proteins") from well-dispersed nanoparticles, which remain isolated due to a stabilizing corona involving other different types of proteins. Our study shows that the "biological identity" (obtained after the particles have interacted with proteins) and aggregation state (clustered versus isolated) of nanoparticles depend not only on their initial surface coating, but also on the concentration of plasma in the suspension. Low plasma concentrations (which are generally used in vitro) lead to different protein/nanoparticle complexes than pure plasma, which reflects the in vivo conditions. As a consequence, by mimicking in vivo conditions, we show that macrophages can perceive several different populations of nanoparticle/protein complexes (differing in physical state and in nature of associated proteins) and uptake them to a different extent. When extrapolated to what would happen in vivo, our results suggest a range of cell responses to a variety of nanoparticle/protein complexes which circulate in the body, thereby impacting their tissue distribution and their efficiency and safety for diagnostic and therapeutic use.


Subject(s)
Blood Proteins/metabolism , Macrophages/metabolism , Magnetic Phenomena , Nanoparticles/chemistry , Nanotechnology/methods , Adsorption , Biological Transport , Blood Proteins/chemistry , Cell Line , Ferric Compounds/chemistry , Ferric Compounds/metabolism , Humans , Protein Binding , Serum Albumin/chemistry , Serum Albumin/metabolism , Surface Properties
18.
J Am Chem Soc ; 133(27): 10459-72, 2011 Jul 13.
Article in English | MEDLINE | ID: mdl-21604803

ABSTRACT

Synthesis of functionalized magnetic nanoparticles (NPs) for biomedical applications represents a current challenge. In this paper we present the synthesis and characterization of water-dispersible sugar-coated iron oxide NPs specifically designed as magnetic fluid hyperthermia heat mediators and negative contrast agents for magnetic resonance imaging. In particular, the influence of the inorganic core size was investigated. To this end, iron oxide NPs with average size in the range of 4-35 nm were prepared by thermal decomposition of molecular precursors and then coated with organic ligands bearing a phosphonate group on one side and rhamnose, mannose, or ribose moieties on the other side. In this way a strong anchorage of the organic ligand on the inorganic surface was simply realized by ligand exchange, due to covalent bonding between the Fe(3+) atom and the phosphonate group. These synthesized nanoobjects can be fully dispersed in water forming colloids that are stable over very long periods. Mannose, ribose, and rhamnose were chosen to test the versatility of the method and also because these carbohydrates, in particular rhamnose, which is a substrate of skin lectin, confer targeting properties to the nanosystems. The magnetic, hyperthermal, and relaxometric properties of all the synthesized samples were investigated. Iron oxide NPs of ca. 16-18 nm were found to represent an efficient bifunctional targeting system for theranostic applications, as they have very good transverse relaxivity (three times larger than the best currently available commercial products) and large heat release upon application of radio frequency (RF) electromagnetic radiation with amplitude and frequency close to the human tolerance limit. The results have been rationalized on the basis of the magnetic properties of the investigated samples.


Subject(s)
Carbohydrates/chemistry , Ferric Compounds/chemistry , Magnetite Nanoparticles/chemistry , Water/chemistry , Ferric Compounds/therapeutic use , Humans , Hyperthermia, Induced/methods , Magnetite Nanoparticles/therapeutic use
19.
Phys Chem Chem Phys ; 13(6): 2111-3, 2011 Feb 14.
Article in English | MEDLINE | ID: mdl-21152579

ABSTRACT

The autocatalytic sonochemical reaction of Fe(CO)(5) decomposition in [BuMeIm][Tf(2)N] provides iron nanoparticles in higher yields than in tetralin. Such a difference is explained by the higher decomposition of the intermediate Fe(3)(CO)(12) according to the two-sites model of the sonochemical reactions and the specific properties of the ionic liquid.

20.
Org Lett ; 11(14): 2992-5, 2009 Jul 16.
Article in English | MEDLINE | ID: mdl-19545163

ABSTRACT

Water-soluble biocompatible rhamnose-coated Fe(3)O(4) nanoparticles of 4.0 nm are obtained by covalent anchorage of rhamnose on the nanoparticles surface via a phosphate linker. These nanoparticles present superparamagnetic behavior and nuclear relaxivities in the same order of magnitude as Endorem that make them potential magnetic resonance imaging (MRI) contrast agents of a second generation, where the saccharides represent also specific ligands able to target lectins on skin cells.


Subject(s)
Contrast Media/chemical synthesis , Ferrosoferric Oxide/chemistry , Magnetic Resonance Imaging/methods , Nanoparticles , Rhamnose/chemistry , Contrast Media/chemistry , Humans , Lectins/drug effects , Molecular Structure , Skin/cytology , Skin/drug effects , Solubility , Water/chemistry
SELECTION OF CITATIONS
SEARCH DETAIL
...