Temperature and Redox Dual‐Responsive Biodegradable Nanogels for Optimizing Antitumor Drug Delivery

The strategy to efficiently deliver antitumor drugs via nanocarriers to targeted tumor sites and achieve controllable drug release is attracting great research interest in cancer therapy. In this study, a novel type of disulfide‐bonded poly(vinylcaprolactam) (PVCL)‐based nanogels with tunable volume phase transition temperature and excellent redox‐labile property are prepared. The nanogels are hydrophilic and swell at 37 °C, whereas under hyperthermia (e.g., 41 °C), the nanogels undergo sharp hydrophilic/hydrophobic transition and volume collapse, which enhances the cellular uptake and drug release. The incorporation of disulfide bond linkers endows the nanogels with an excellent disassembly property in reducing environments, which greatly facilitates drug release in tumor cells. Nanogels loaded with doxorubicin (DOX) (DOX‐NGs) (DOX‐NGs) are stable in physiological conditions with low drug leakage (15% in 48 h), while burst release of DOX (92% in 12 h) can be achieved in the presence of 10 × 10^?3 m glutathione and under hyperthermia. The DOX‐NGs possess improved cell killing efficiency under hyperthermia (IC₅₀ decreased from 1.58 μg mL^?1 under normothermia to 0.5 μg mL^?1). Further, the DOX‐NGs show a pronounced tumor inhibition rate of 46.6% compared with free DOX, demonstrating that this new dual‐responsive nanogels have great potential as drug delivery carriers for cancer therapy in vivo.     

Amphiphilic Drug Delivery Microcapsules via Layer-by-Layer Self-Assembly

A strategy to incorporate and release the amphiphilic drugs of doxorubicin (DOX) and ibuprofen (IBU) in the same microcapsules is introduced, A layer-by-layer (LbL) assembly of microcapsules with doxorubicin hydrochloride (DOX) or green fluorescent agent, hydrophilic fluorescein isothiocyanate (FITC), encapsulated in CaCO₃ microparticle templates, was conducted via alternatively depositing sodium carboxymethyl cellulose (CMC) and chitosan (CHI) onto IBU or red fluorescent agent (hydrophobic Nile Red) preloaded poly-L-lactide (PLLA) coated magnetic Fe₃O₄-DOX-loaded CaCO₃ (or FITC-loaded) templates. The structure, morphology, composition, magnetic properties and drugs distribution of the obtained microcapsules were characterized by nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), zeta potential analysis, thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM) and confocal laser scanning microscopy. The fluorescent agents loading of FITC and Nile Red were confirmed by observations using confocal laser scanning microscopy. Fluorescence observations showed that the DOX was distributed both in the walls and in the cavities of the microcapsules, while IBU was present in the capsule wall. The in–vitro release of the dual drugs, DOX and IBU, from the microcapsules with different numbers of CHI and CMC layers was characterized. A tunable amount of drug release was achieved by changing the number of layers. The release study indicated that the LBL microcapsules exhibited better sustained release capacity compared to the uncoated microcapsules. The microcapsules inherited a strong magnetic property from the Fe₃O₄ nanoparticles, sufficient for targeting and magnetic hyperthermia drug delivery systems.     

Amphiphilic Core–Shell Nanocomposite Particles for Enhanced Magnetic Resonance Imaging

A scalable synthesis of magnetic core–shell nanocomposite particles, acting as a novel class of magnetic resonance (MR) contrast agents, has been developed. Each nanocomposite particle consists of a biocompatible chitosan shell and a poly(methyl methacrylate) (PMMA) core where multiple aggregated γ‐Fe₂O₃ nanoparticles are confined within the hydrophobic core. Properties of the nanocomposite particles including their chemical structure, particle size, size distribution, and morphology, as well as crystallinity of the magnetic nanoparticles and magnetic properties were systematically characterized. Their potential application as an MR contrast agent has been evaluated. Results show that the nanocomposite particles have good stability in biological media and very low cytotoxicity in both L929 mouse fibroblasts (normal cells) and HeLa cells (cervical cancer cells). They also exhibited excellent MR imaging performance with a T₂ relaxivity of up to 364 mM_Fe^?1 s^?1. An in vivo MR test performed on a naked mouse bearing breast tumor indicates that the nanocomposite particles can localize in both normal liver and tumor tissues. These results suggest that the magnetic core–shell nanocomposite particles are an efficient, inexpensive and safe T₂‐weighted MR contrast agent for both liver and tumor MR imaging in cancer therapy.     

Construction of a Dual Drug Carrier on the Basis of Hollow Structured Upconversion Nanoparticles for pH‐Responsive Drug Delivery and UCL/MRI Dual Mode Imaging

A series of Gd³⁺ doping hollow upconversion nanoparticles NaYF₄:Yb,Gd,Tm (h‐UNCP) are prepared successfully. The hollow NaYF₄:Yb,Gd,Tm possess excellent upconversion luminescence (UCL) and large longitudinal relativity (r₁ = 128.3 mm ^?1 s^?1), which can be potentially used for UCL/magnetic resonance imaging (MRI) dual mode imaging. On the basis of the optimal h‐UCNP, doxorubicin hydrochloride (DOX) and methotrexate (MTX) are used as drug models to prepare a dual drug carrier. After the encapsulation of DOX on the h‐UCNP, chitosan (CS) is further wrapped and then used to load MTX to obtain a dual drug carrier h‐UCNPs/DOX/CS/MTX. The pH responsive release of DOX and MTX is discussed. The MTX release climbs from 33% to 100% by regulating the pH from 5.8 to 7.4. The DOX release is different at different pH conditions. The synergistic effect of DOX and MTX on the cancer cells is confirmed by cell viability. The h‐UCNPs/DOX/CS/MTX are tracked by cells UCL imaging and vivo MRI imaging. The excellent performance of UCL imaging and positive MRI images demonstrates that h‐UCNPs/DOX/CS/MTX can be used for UCL/MRI dual mode imaging. All the results show the potential application of h‐UCNPs/DOX/CS/MTX in pH responsive release and UCL/MRI dual imaging.     

Superparamagnetic iron oxide particles and positive enhancement for myocardial perfusion studies assessed by subsecond T1-weighted MRI

Superparamagnetic iron oxide particles (SPIOs) are usually referred to as T₂ MR contrast agents, reducing signal intensity (SI) on T₂-weighted MR images (negative enhancement). This study reports the original use of SPIOs as T₁-enhancing contrast agents, primarily assessed in vitro, and then applied to an in vivo investigation of a myocardial perfusion defect. Using a strongly T₁-weighted subsecond MR sequence with SPIOs intravenous (IV) bolus injection, MR imaging of myocardial vascularization after reperfusion was performed, on a dog model of coronary occlusion followed by reperfusion. Immediately after the intravenous bolus injection of 20 μmol/kg of SPIOs, a positive signal intensity enhancement was observed respectively, in the right and left ventricular cavity and in the nonischemic left myocardium. Moreover, compared to normal myocardium, the remaining ischemic myocardial region (anterior wall of the left ventricle) appeared as a lower and delayed SI enhancing area (cold spot). Mean peak SIE in the nonischemic myocardium (posterior wall) was significantly higher than in the ischemic myocardium (anterior wall) (110 ± 23% vs. 74 ± 22%, Mann-Whitney test < 1%, n₁ = 6, n₂ − n₁ = 0, U > 2). In conclusion, the T₁ effect of SPIOs at low dose, during their first intravascular distribution, suggests their potential use as positive markers to investigate the regional myocardial blood flow and some perfusion defects such as the “no-reflow phenomenon”.     

High Rate and Long Cycle Life of a CNT/rGO/Si Nanoparticle Composite Anode for Lithium‐Ion Batteries

Si nanoparticle (Si‐NP) composite anode with high rate and long cycle life is an attractive anode material for lithium‐ion battery (LIB) in hybrid electric vehicle (HEV)/pure electric vehicle (PEV). In this work, a carbon nanotube (CNT)/reduced graphene oxide (rGO)/Si nanoparticle composite with alternated structure as Li‐ion battery anode is prepared. In this structure, rGO completely wraps the entire Si/CNT networks by different layers and CNT networks provide fast electron transport pathways with reduced solid‐state diffusion, so that the stable solid‐electrolyte interphase layer can form on the whole surface of the matrix instead of on single Si nanoparticle, which ensure the high cycle stability to achieve the excellent cycle performance. As a result, the CNT/rGO/Si‐NP anode exhibits high performances with long cycle life (≈455 mAh g^?1 at 15 A g^?1 after 2000 cycles), high specific charge capacity (≈2250 mAh g^?1 at 0.2 A g^?1, ≈650 mAh g^?1 at 15 A g^?1), and fast charge/discharge rates (up to 16 A g^?1). This nanostructure anode with facile and low‐cost synthesis method, as well as excellent electrochemical performances, makes it attractive for the long life cycles at high rate of the next generation LIB applications in HEV/PEV.     

In Vitro Evaluation of Non‐Protein Adsorbing Breast Cancer Theranostics Based on 19F‐Polymer Containing Nanoparticles

Eight fluorinated nanoparticles (NPs) are synthesized, loaded with doxorubicin (DOX), and evaluated as theranostic delivery platforms to breast cancer cells. The multifunctional NPs are formed by self‐assembly of either linear or star‐shaped amphiphilic block copolymers, with fluorinated segments incorporated in the hydrophilic corona of the carrier. The sizes of the NPs confirm that small circular NPs are formed. The release kinetics data of the particles reveals clear hydrophobic core dependence, with longer sustained release from particles with larger hydrophobic cores, suggesting that the DOX release from these carriers can be tailored. Viability assays and flow cytometry evaluation of the ratios of apoptosis/necrosis indicate that the materials are non‐toxic to breast cancer cells before DOX loading; however, they are very efficient, similar to free DOX, at killing cancer cells after drug encapsulation. Both flow cytometry and confocal microscopy confirm the cellular uptake of NPs and DOX‐NPs into breast cancer cells, and in vitro ¹⁹F‐MRI measurement shows that the fluorinated NPs have strong imaging signals, qualifying them as a potential in vivo contrast agent for ¹⁹F‐MRI.     

Liquid‐Crystal‐Mediated Self‐Assembly of Porous α‐Fe2O3 Nanorods on PEDOT:PSS‐Functionalized Graphene as a Flexible Ternary Architecture for Capacitive Energy Storage

A novel aqueous‐based self‐assembly approach to a composite of iron oxide nanorods on conductive‐polymer (CP)‐functionalized, ultralarge graphene oxide (GO) liquid crystals (LCs) is demonstrated here for the fabrication of a flexible hybrid material for charge capacitive application. Uniform decoration of α‐Fe₂O₃ nanorods on a poly(3,4‐ethylene‐dioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)‐functionalized, ultralarge GO scaffold results in a 3D interconnected layer‐by‐layer (LBL) architecture. This advanced interpenetrating network of ternary components is lightweight, foldable, and possesses highly conductive pathways for facile ion transportation and charge storage, making it promising for high‐performance energy‐storage applications. Having such structural merits and good synergistic effects, the flexible architecture exhibits a high specific discharge capacitance of 875 F g^?1 and excellent volumetric specific capacitance of 868 F cm^?3 at 5 mV s^?1, as well as a promising energy density of 118 W h kg^?1 (at 0.5 A g^?1) and promising cyclability, with capacity retention of 100% after 5000 charge–discharge (CD) cycles. This synthesis method provides a simple, yet efficient approach for the solution‐processed LBL insertion of the hematite nanorods (HNR) into CP‐functionalized novel composite structure. It provides great promise for the fabrication of a variety of metal‐oxide (MO)‐nanomaterial‐based binder and current collector‐free flexible composite electrodes for high‐performance energy‐storage applications.     

Glutathione‐Mediated Degradation of Surface‐Capped MnO2 for Drug Release from Mesoporous Silica Nanoparticles to Cancer Cells

Owing to its higher concentration in cancer cells than that in the corresponding normal cells, glutathione (GSH) provides an effective and flexible mechanism to design drug delivery systems. Here a novel GSH‐responsive mesoporous silica nanoparticle (MSN) is reported for controlled drug release. In this system, manganese dioxide (MnO₂) nanostructure, formed by the reduction of KMnO₄ on the surface of carboxyl‐functionalized MSN can block the pores (MSN@MnO₂). By a redox reaction, the capped MnO₂ nanostructure can dissociate into Mn²⁺ in the presence of GSH molecules. The blocked pores are then uncapped, which result in the release of the entrapped drugs. As a proof‐of‐concept, doxorubicin (DOX) as model drug is loaded into MSN@MnO₂. DOX‐loaded MSN@MnO₂ shows an obvious drug release in 10 × 10^?3 m GSH, while no release is observed in the absence of GSH. In vitro studies using human hepatocellular liver carcinoma cell line (HepG2) prove that the DOX‐loaded MSN@MnO₂ can entry into HepG2 cells and efficiently release the loaded DOX, leading to higher cytotoxicity than to that of human normal liver cells (L02). It is believed that further developments of this GSH‐responsive drug delivery system will lead to a new generation of nanodevices for intracellular controlled delivery.     

Theranostic Iron@Gold Core–Shell Nanoparticles for Simultaneous Hyperthermia‐Chemotherapy upon Photo‐Stimulation

The challenges of nanoparticles, such as size‐dependent toxicity, nonbiocompatibility, or inability to undergo functionalization for drug conjugation, limit their biomedical application in more than one domain. Oval‐shaped iron@gold core–shell (oFe@Au) magnetic nanoparticles are engineered and their applications in magnetic resonance imaging (MRI), optical coherence tomography (OCT), and controlled drug release, are explored via photo stimulation‐generated hyperthermia. The oFe@Au nanoparticles have a size of 42.57 ± 5.99 nm and consist of 10.76 and 89.24 atomic % of Fe and Au, respectively. Upon photo‐stimulation for 10 and 15 minutes, the levels of cancer cell death induced by methotrexate‐conjugated oFe@Au nanoparticles are sixfold and fourfold higher, respectively, than oFe@Au nanoparticles alone. MRI and OCT confirm the application of these nanoparticles as a contrast agent. Finally, results of in vivo experiments reveal that the temperature is elevated by 13.2 °C, when oFe@Au nanoparticles are irradiated with a 167 mW cm^?2 808 nm laser, which results in a significant reduction in tumor volume and scab formation after 7 days, followed by complete disappearance after 14 days. The ability of these nanoparticles to generate heat upon photo‐stimulation also opens new doors for studying hyperthermia‐mediated controlled drug release for cancer therapy. Applications include biomedical engineering, cancer therapy, and theranostics fields.     

Internal Structure and Magnetic Properties in Cobalt Ferrite Nanoparticles: Influence of the Synthesis Method

The design of novel nanostructured magnetic materials requires a good understanding of the variation in the magnetic properties due to different synthesis conditions. In this work, four different procedures for fabricating Co‐ferrite nanoparticles with similar sizes between 7 and 10 nm are compared by studying their structural and magnetic properties. Non‐aqueous methods based on the thermal decomposition of metal acetylacetonates at high temperatures, either with or without surfactants, provide highly crystalline nanoparticles with large saturation magnetization values and a coherent reversal of the magnetic moment. However, variations in the density of defects and in the shape of the nanocrystals determine the distribution of switching fields and the effective magnetic anisotropy, which reaches up to ≈1 × 10⁷ erg cm^?3 for oleic acid‐capped 9 nm nanoparticles. It is shown that the saturation magnetization values for nanoparticles produced by different methods are in the range between 49 and 95 emu g^?1 due to differences in the stoichiometry, in the cation occupancy, in the magnetic disorder and in the spin canting of the magnetic sub‐lattices, the latter evaluated by in‐field Mössbauer spectroscopy.     

Solute Permeability of Certain Polymeric Films Applied on Aspirin Crystals to Form Microcapsules

A study was carried out to investigate the solute permeability of various polymer films applied on aspirin crystal to form microcapsules. The coating materials were an acrylate methacrylate (AMA), poly 3‐hydroxybutyrate‐hydroxyvalerate (Biopol^®) and poly (lactic‐glycolic) acid (PLGA). Organic solutions of the polymers were applied on the aspirin crystals (core) by a spray coating technique in a Wurster column. The microcapsule surfaces were investigated using scanning electron microscopy (SEM), while permeability studies were carried out on single microcapsules serving as micro dialysis cells. The amount of drug (m) permeating through the applied films in time (t) was analysed on the basis of Fickian diffusion. The SEM revealed numerous surface pores of size range 2.4 to 24 μm for the AMA films, while the PLGA and Biopol films, on the other hand, exhibited very few surface pores of size range 2.2 to 18 μm. However, the AMA films were more spongy than the PLGA and Biopol. The AMA films displayed a retarded release while the PLGA or Biopol films displayed a burst release, attributable to the differences in the film's porous structure. The Permeability coefficient (P) depended on the core weight of the single microcapsules, decreasing with increase in core weight. Thus, for an ensemble of the microcapsules the permeability coefficients of the films of the component microcapsules will have a distribution of P values even though the coating material is the same. This finding is important in the simulation of drug release from coated multiparticulate systems.     

A Functionalized Hollow Mesoporous Silica Nanoparticles‐Based Controlled Dual‐Drug Delivery System for Improved Tumor Cell Cytotoxicity

Multifunctional nanoparticles for selectively targeting tumor cells and effectively delivering multiple drugs are urgently needed in cancer therapy. Here, a dual‐drug delivery system is prepared, based on functionalized hollow mesoporous silica nanoparticles (HMSNs). Doxorubicin (DOX) hydrochloride is loaded into the hollow core, and dichloro(1,2‐diaminocyclohexane)platinum (II) (DACHPt) is stored in the pores of the shell by the coordination interaction with the carboxyl groups modified on the pore walls, which also serves as barriers to control the DOX release. Detailed studies in vitro indicate that the DACHPt release is triggered by Cl^? through the cleavage of the coordination interaction, and the DOX release depends on the release rate of DACHPt and the environmental pH value. The surface of the mechanized nanoparticles is also modified by transferrin (Tf) to achieve the tumor specificity. Compared with individual drug delivery systems, the dual‐drug delivery system shows synergistic efficacy on the cell cytotoxicity (combination index = 0.30), resulting in improved tumor cell killing. The present dual‐drug delivery system provides a promising strategy to develop controlled and targeted combination therapies for efficient cancer treatment.     

Facile Synthesis of Gd(OH)3‐Doped Fe3O4 Nanoparticles for Dual‐Mode T1‐ and T2‐Weighted Magnetic Resonance Imaging Applications

The facile hydrothermal synthesis of polyethyleneimine (PEI)‐coated iron oxide (Fe₃O₄) nanoparticles (NPs) doped with Gd(OH)₃ (Fe₃O₄‐Gd(OH)₃‐PEI NPs) for dual mode T₁‐ and T₂‐weighted magnetic resonance (MR) imaging applications is reported. In this approach, Fe₃O₄‐Gd(OH)₃‐PEI NPs are synthesized via a hydrothermal method in the presence of branched PEI and Gd(III) ions. The PEI coating onto the particle surfaces enables further modification of poly(ethylene glycol) (PEG) in order to render the particles with good water dispersibility and improved biocompatibility. The formed Fe₃O₄‐Gd(OH)₃‐PEI‐PEG NPs have a Gd/Fe molar ratio of 0.25:1 and a mean particle size of 14.4 nm and display a relatively high r₂ (151.37 × 10^?3m ^?1 s^?1) and r₁ (5.63 × 10^?3m ^?1 s^?1) relaxivity, affording their uses as a unique contrast agent for T₁‐ and T₂‐weighted MR imaging of rat livers after mesenteric vein injection of the particles and the mouse liver after intravenous injection of the particles, respectively. The developed Fe₃O₄‐Gd(OH)₃‐PEI‐PEG NPs may hold great promise to be used as a contrast agent for dual mode T₁‐ and T₂‐weighted self‐confirmation MR imaging of different biological systems.     

Porous Silicon@Polythiophene Core–Shell Nanospheres for Lithium‐Ion Batteries

Polythiophene‐coated porous silicon core–shell nanospheres (Si@PTh) composite are synthesized by a simple chemical oxidative polymerization approach. The polythiophene acts as a flexible layer to hold silicon grains when they are repeatedly alloying/dealloying with lithium during the discharge/charge process. The long lifespan and high‐current‐density rate ­capability (at a current of 8 A g^?1) of the Si@PTh composite are vastly improved compared with as‐prepared Si spheres. Typically, these Si@PTh composite electrodes achieve a reversible capacity of 1130.5 mA h g^?1 at 1 A g^?1 current density after 500 cycles, and can even possess a discharge capacity up to 451.8 mA h g^?1 at 8 A g^?1. The improved electrochemical performance can be ascribed to the synergy effects of the flexible PTh coating and the distinctive core–shell nanospheres with porous structure, which can largely alleviate the volume expansion of the Si during alloying with lithium.     

Controlling magnetic properties of iron oxide nanoparticles using post-synthesis thermal treatment

Changes in morphological and magnetic properties of Fe₃O₄ nanoparticles before and after annealing are investigated in the present work. The nanoparticles are synthesized in a standard capacitively coupled plasma enhanced chemical vapour deposition system with two electrodes using ferrocene as the source compound. Post annealing, due to the sintering process, the particles fuse along with recrystallization. This results in increased size of the nanoparticles and the interparticle interaction, which play a major role in deciding the magnetic properties. X-ray diffraction patterns of the samples before and after annealing indicate a phase change from Fe₃O₄ to Fe₂O₃. Annealing at 200 ^°C causes the apparent saturation magnetization to increase from 6 emu?g^?1 to 15 emu?g^?1. When annealed at 500 ^°C, the magnetic properties of the nanoparticles resemble those of the bulk material. The evidence for the transition from a superparamagnetic state to a collective state is also observed when annealed at 500 ^°C. Variation of the magnetic relaxation data with annealing also reflects the change in the magnetic state brought about by the annealing. The correlation between annealing temperature and the magnetic properties can be used to obtain nanocrystallites of iron oxide with different sizes and magnetic properties.     

HoF3 and DyF3 Nanoparticles as Contrast Agents for High‐Field Magnetic Resonance Imaging

Clinical contrast agents (CAs) currently used in magnetic resonance imaging (MRI) at low fields are less effective at high magnetic fields. The development of new CAs is mandatory to improve diagnostic capabilities of the new generation of high field MRI scanners. The purpose of this study is to synthesize uniform, water dispersible LnF₃ (Ln = Ho, Dy) nanoparticles (NPs) and to evaluate their relaxivity at high magnetic field (9.4 T) as a function of size and composition. Two different types of HoF₃ NPs are obtained by homogeneous precipitation in ethylene glycol at 120 °C. The use of holmium acetate as holmium precursor leads to rhombus‐like nanoparticles, while smaller, ellipsoid‐like nanoparticles are obtained when nitrate is used as the holmium salt. To explain this behavior, the mechanism of formation of both kinds of particles is analyzed in detail. Likewise, rhombus‐like DyF₃ nanoparticles are prepared following the same method as for the rhombus‐like HoF₃ nanoparticles. We have found, to the best of knowledge, the highest transverse relaxivity values at 9.4 T described in the literature for this kind of CAs. Finally, the LnF₃ NPs have shown negligible cytotoxicity for C6 rat glioma cells for concentrations up to 0.1 mg mL^?1.     

Clustering of Iron Oxide Nanoparticles with Amphiphilic Invertible Polymer Enhances Uptake and Release of Drugs and MRI Properties

A functionalization of iron oxide nanoparticles (NPs) of different diameters by the amphiphilic invertible polymer, (PEG600‐alt‐PTHF650)_k (PEG and PTHF stand for poly(ethylene glycol) and poly(tetrahydrofuran), respectively), leads to different NP/polymer architectures for dye/drug uptake and release, as is reported here for the first time. It is demonstrated that 18.6 ± 1.4 and 11.9 ± 0.6 nm NPs are individually coated by this polymer, while 5.9 ± 0.6 nm NPs form nanoparticle clusters (NPCs) which could be isolated by either ultracentrifugation or magnetic separation. This phenomenon is most likely due to the character of the (PEG600‐alt‐PTHF650)_k macromolecule with alternating hydrophilic and hydrophobic fragments and its dimensions sufficient to cause NP clustering. Utilizing Rhodamine B base (RBB) and doxorubicin (DOX), the data on uptake upon mixing and further release via inversion into octanol (mimicking the penetration of the cell biomembrane) are presented. The magnetic NPCs display enhanced uptake and release of both RBB and DOX most likely due to the higher retained polymer amount. The NPCs also display exceptional magnetic resonance imaging properties. This and the high uptake/release efficiency of the NPCs combined with easy magnetic separation make them promising for theranostic probes for magnetically targeted drug delivery.     

Functionalized Biomimetic Magnetic Nanoparticles as Effective Nanocarriers for Targeted Chemotherapy

Novel MamC‐mediated biomimetic magnetic nanoparticles (BMNPs) are proposed as valuable carriers for targeted chemotherapy because of the size (36 ± 12 nm) and of surface properties conferred by MamC coating. They are super‐paramagnetic at room and body temperatures, have a large magnetic moment per particle, mediate hyperthermia, are cytocompatible, and, having a negative surface charge at physiological pH, can be efficiently coupled with DOXOrubicin (DOXO) and a monoclonal antibody (mAb) directed against the human Met/hepatocyte growth factor receptor (overexpressed in many cancers) displaying coupling stability, while releasing DOXO at acidic pH. This release can be enhanced by hyperthermia. The DOXO‐mAb‐BMNPs selectively recognize Met, bind efficiently to Met⁺ tumor cells, and discharge DOXO within their nuclei more efficiently than DOXO‐BMNPs, exerting cytotoxicity. These data represent proof of concept for future in vivo experiments in which the controlled dual targeting (mAb‐mediated and magnetic) approach and combined (chemotherapy and hyperthermia) therapy will be studied.     

Performances of a metallic magnetic calorimeter for the measurement of hard X‐ray emission intensities

The energy spectrum analysis of X‐ray intensities with semiconductor detectors is often difficult because their energy resolution is usually not good enough to separate the different X‐ray lines. Metallic magnetic calorimeters (MMCs) can be an alternative; they can offer both high energy resolution and high intrinsic detection efficiency from 0 to 100 keV. MMCs are thermal detectors; that is to say, the energy of each absorbed photon is measured as a temperature elevation. At very low temperature, typically few tens of mK, a very large pulse height‐to‐noise ratio can be obtained that is an essential condition for high energy resolution. We are involved in the development of MMCs for metrology applications such as the determination of hard X‐ray emission intensities. For that purpose, we conceived an MMC with an energy resolution of 57 eV around 30 keV. The absorber is made of gold providing high intrinsic detection efficiency even for a small volume, greater than 90% below 60 keV. We will describe the physical principle and the practical realisation of this detector and discuss its performances by analysing the energy spectrum obtained from a ¹³³Ba source. Preliminary outcomes of relative emission intensities of the K X‐ray of cesium are presented and compared with other experimental data and theoretical calculations. Copyright © 2012 John Wiley & Sons, Ltd.