Gas-Generating,pH-Responsive Calcium Carbonate Hybrid Particles with Biomimetic Coating for Contrast-Enhanced Ultrasound Imaging

This work reports the fabrication of biocompatible and pH-sensitive hybrid polydopamine/bovine serum albumin/calcium carbonate (PDA/BSA/CaCO₃) particles via a rapid precipitation method. These hybrid particles generate hyperechogenic carbon dioxide bubbles upon exposure to low pH environments, making them ideal as a contrast agent and detector for tumor cells. This study also highlights the application of red blood cell membrane (RBC)-derived membranes as a biomimetic coating for PDA/BSA/CaCO₃ hybrid particles in order to modulate protein corona formation, a natural physiological response that alters tailored properties of most nanomaterials that are administered systemically. Results of this work demonstrate that the RBC membrane-coated hybrid particles are ideal for a wide range of biomedical applications, such as noninvasive multimodal imaging, photothermal and photodynamic therapy, and “personalized” drug delivery systems.     

Bonding strength of HA/ZrO2 biomaterials with different interlayers

Yttria-tetragonal zirconia polycrystal (Y-TZP) ceramic with hydroxyapatite (HA) coating has been recognized as one of the most common biomaterials. However, its lower interfacial bonding strength has restricted its clinical application. In this study, CaCO₃, Ca₃(PO₄)₂ (TCP), and Ag were added into the interface of the HA coating and Y-TZP substrate by a pressureless sintering process to increase interfacial bonding strength. The morphology and microstructure of the interlayers were analyzed by scanning electronic microscope. The results show that the comprehensive performances of HA/interlayer/ZrO₂ biomaterials were much better than that of the sample without interlayer, and the shear and tensile strengths of the HA/CaCO₃/ZrO₂ biomaterial reached 15.19 and 16.88 MPa, respectively, which were higher than those of TCP and Ag. The CaZrO₃ and carbonated apatite, formed by decomposed products of CaCO₃ and HA reacting with ZrO₂ at the interface under sintering, increased the mechanical properties of the biomaterial.     

Magnetization reversal in [Ni/Pt]6/Pt(x)/[Co/Pt]6 multilayers

The magnetization reversal is studied in magnetron sputtered artificial superstructures of the form [Ni/Pt]₆/Pt(x)/[Co/Pt]₆ with perpendicular anisotropy, in which the [Co/Pt]₆ stacks have higher coercivity than the [Ni/Pt]₆. For x≥2 nm the two stacks reverse separately and exhibit characteristic stepped loops with a “plateau” in the region between the two switching fields. First-Order Reversal Curves (FORCs) reveal that the maximum coupling is obtained for x=1.5 nm. While each of the Ni/Pt and Co/Pt stacks by itself is thin enough to reverse in large domains when they are coupled, formation of maze like domains is observed. In this case some reversibility of the demagnetization curves associated with interfacial domain wall pinning appears while in the rest of the cases the reversal mechanism is based on lateral domain wall pinning with low reversibility. In the loops monitored by Extraordinary Hall Effect (EHE) measurements this “plateau” appears as a hump due to the different sign of the EHE coefficient between the [Ni/Pt]₆ and [Co/Pt]₆.     

Core–Shell Bi2Se3@mSiO2‐PEG as a Multifunctional Drug‐Delivery Nanoplatform for Synergistic Thermo‐Chemotherapy with Infrared Thermal Imaging of Cancer Cells

Thermo‐chemotherapy combining photothermal therapy (PTT) with chemotherapy has become a potent approach for antitumor treatment. In this study, a multifunctional drug‐delivery nanoplatform based on polyethylene glycol (PEG)‐modified mesoporous silica‐coated bismuth selenide nanoparticles (referred to as Bi₂Se₃@mSiO₂‐PEG NPs) is developed for synergistic PTT and chemotherapy with infrared thermal (IRT) imaging of cancer cells. The product shows no/low cytotoxicity, strong near‐infrared (NIR) optical absorption, high photothermal conversion capacity, and stability. Utilizing the prominent photothermal effect, high‐contrast IRT imaging and efficient photothermal killing effect on cancer cells are achieved upon NIR laser irradiation. Moreover, the successful mesoporous silica coating of the Bi₂Se₃@mSiO₂‐PEG NPs cannot only largely improve the stability but also endow the NPs high drug loading capacity. As a proof‐of‐concept model, doxorubicin (DOX) is successfully loaded into the NPs with rather high loading capacity (≈50.0%) via the nanoprecipitation method. It is found that the DOX‐loaded NPs exhibit a bimodal on‐demand pH‐ and NIR‐responsive drug release property, and can realize effective intracellular drug delivery for chemotherapy. The synergistic thermo‐chemotherapy results in a significantly higher antitumor efficacy than either PTT or chemotherapy alone. The work reveals the great potential of such core–shell NPs as a multifunctional drug‐delivery nanosystem for thermo‐chemotherapy.     

Coassembled Nanoparticles Composed of Functionalized Mesoporous Silica and Pillar[5]arene-Appended Gold Nanoparticles as Mitochondrial-Selective Dual-Drug Carriers

Coassembled nanoparticles composed of functionalized mesoporous silica and pillar[5]arene-appended Au nanoparticles obtained through the formation of a host–guest complex are designed and synthesized as a mitochondrial-selective dual-drug delivery system. A pyridinium-based ligand and fluorescein isothiocyanate are immobilized onto mesoporous silica to act as the mitochondria-targeting ligand and fluorescence tracker, respectively, of a material dubbed NP-3. Carboxylated pillar[5]arene-capped Au nanoparticles (CP-AuNPs) are fabricated by the templated reduction of Au³⁺. Interestingly, coassembled nanoparticles (NP-1) composed of doxorubicin (DOX) loaded NP-3 and CP-AuNPs are then prepared via the formation of a host–guest complex between the pyridinium-based ligand of NP-3 and the pillar[5]arene of CP-AuNPs. To demonstrate the effectiveness of NP-2 and NP-1 as mitochondrial targeting drug delivery systems, DOX and F16 are employed as model drugs. These drugs loaded onto NP-2 and CP-AuNPs, respectively, are selectively delivered to mitochondria, indicating the usefulness of NP-2 and CP-AuNPs as mitochondrial-specific drug-delivery carriers in cancer cells. More interestingly, the use of NP-1 is also associated with the selective accumulation of DOX and F16 in mitochondria. The selective mitochondrial-targeting of NP-1 is possible by NP-2 and F16 exposed to the cytoplasm, allowing the codelivery of the two drugs to the mitochondria.     

A Multifunctional Nanocrystalline CaF2:Tm,Yb@mSiO2 System for Dual‐Triggered and Optically Monitored Doxorubicin Delivery

Daunting challenges in investigating the controlled release of drugs in complicated intracellular microenvironments demand the development of stimuli‐responsive drug delivery systems. Here, a nanoparticle system, CaF₂:Tm,Yb@mSiO₂, made of a mesoporous silica (mSiO₂) nanosphere with CaF₂:Tm,Yb upconversion nanoparticles (UCNPs) is developed, filling its mesopores and with its surface‐modified with polyacrylic acid for binding the anticancer drug molecules (doxorubicin, DOX). The unique design of CaF₂:Tm,Yb@mSiO₂ enables us to trigger the drug release by two mechanisms. One is the pH‐triggered mechanism, where drug molecules are preferentially released from the nanoparticles at acidic conditions unique for the intracellular environment of cancer cells compared to normal cells. Another is the 808 nm near infrared (NIR)‐triggered mechanism, where 808 nm NIR induces the heating of the nanoparticles to weaken the electrostatic interaction between drug molecules and nanoparticles. In addition, luminescence resonance energy transfer occurs from the UCNPs (the energy donor) to the DOX drug (the energy acceptor) in the presence of 980 nm NIR irradiation, allowing us to monitor the drug release by detecting the vanishing blue emission from the UCNPs. This study demonstrates a new multifunctional nanosystem for dual‐triggered and optically monitored drug delivery, which will facilitate the rational design of personalized cancer therapy.     

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.     

Large spontaneous Hall angle in [Co,CoFe/Pt] multilayer

We have quantitatively investigated the Hall effect in [Co, CoFe/Pt] multilayer films. The [Co, CoFe/Pt] multilayers exhibit large spontaneous Hall resistivity (ρ_H) and Hall angle (ρ_H/ρ). Even though the Hall resistivity in [Co, CoFe/Pt] multilayer films (2.7–4 × 10⁻⁷ Ω cm) is smaller than that of amorphous RE–TM alloy films which show large spontaneous Hall resistivity (<2 × 10⁻⁶ Ω cm), the Hall angle of multilayer (6–8%) is almost twice than that in amorphous rare earth–transition metal alloy films (∼3%). The Hall angle provides evidence of the effects of the exchange interaction of the Hall scattering. The exchange is between conduction electron spins and the localized spins of the transition metal. The large Hall angle of [Co, CoFe/Pt] multilayer can be considered due to the high spin polarization and high Curie temperature of Co and CoFe transition metal layers. Even though the role of interfaces and surfaces in the magnetic properties of multilayer films may dominate that of the bulk, the Hall effects in [Co, CoFe/Pt] multilayer may be mainly dominated by the bulk effect.     

Template-directed hydrothermal synthesis of hydroxyapatite as a drug delivery system for the poorly water-soluble drug carvedilol

In order to improve the dissolution rate and increase the bioavailability of a poorly water-soluble drug, intended to be administered orally, the biocompatible and bioactive mesoporous hydroxyapatite (HA) was successfully synthesized. In the present study, mesoporous HA nanoparticles were produced using Pluronic block co-polymer F127 and cetyltrimethylammonium bromide (CTAB) as templates by the hydrothermal method. The obtained mesoporous HA was employed as a drug delivery carrier to investigate the drug storage/release properties using carvedilol (CAR) as a model drug. Characterizations of the raw CAR powder, mesoporous HA and CAR-loaded HA were carried out by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, N₂ adsorption/desorption, thermogravimetric analysis (TGA), and UV-VIS spectrophotometry. The results demonstrated that CAR was successfully incorporated into the mesoporous HA host. In vitro drug release studies showed that mesoporous HA had a high drug load efficiency and provided immediate release of CAR compared with micronized raw drug in simulated gastric fluid (pH 1.2) and intestinal fluid (pH 6.8). Consequently, mesoporous HA is a good candidate as a drug carrier for the oral delivery of poorly water-soluble drugs.     

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.     

Evidence for biogenic processes during formation of ferromanganese crusts from the Pacific Ocean: Implications of biologically induced mineralization

Ferromanganese [Fe/Mn] crusts formed on basaltic seamounts, gain considerable economic importance due to their high content of Co, Ni, Cu, Zn and Pt. The deposits are predominantly found in the Pacific Ocean in depths of over 1000 m. They are formed in the mixing layer between the upper oxygen-minimum zone and the lower oxygen-rich bottom zone. At present an almost exclusive abiogenic origin of crust formation is considered. We present evidence that the upper layers of the crusts from the Magellan Seamount cluster are very rich in coccoliths/coccolithophores (calcareous phytoplankton) belonging to different taxa. Rarely intact skeletons of these unicellular algae are found, while most of them are disintegrated into their composing prisms or crystals. Studies on the chemical composition of crust samples by high resolution SEM combined with an electron probe microanalyzer (EPMA) revealed that they are built of distinct stacked piles of individual compartments. In the center of such piles Mn is the dominant element, while the rims of the piles are rich in Fe (mineralization aspect). The compartments contain coccospheres usually at the basal part. Energy dispersive X-ray spectroscopy (EDX) analyses showed that those coccospheres contain, as expected, CaCO₃ but also Mn-oxide. Detailed analysis displayed on the surface of the coccolithophores a high level of CaCO₃ while the concentration of Mn-oxide is relatively small. With increasing distance from the coccolithophores the concentration of Mn-oxide increases on the expense of residual CaCO₃. We conclude that coccoliths/coccolithophores are crucial for the seed/nucleation phase of crust formation (biomineralization aspect). Subsequently, after the biologically induced mineralization phase Mn-oxide deposition proceeds “auto”catalytically.     

Temperature and magnetic field responsive hyaluronic acid particles with tunable physical and chemical properties

We report the preparation and characterization of thiolated-temperature-responsive hyaluronic acid-cysteamine-N-isopropyl acrylamide (HA-CYs-NIPAm) particles and thiolated-magnetic-responsive hyaluronic acid (HA-Fe-CYs) particles. Linear hyaluronic acid (HA) crosslinked with divinyl sulfone as HA particles was prepared using a water-in-oil micro emulsion system which were then oxidized HA-O with NaIO₄ to develop aldehyde groups on the particle surface_. HA-O hydrogel particles were then reacted with cysteamine (CYs) which interacted with aldehydes on the HA surface to form HA particles with cysteamine (HA-CYs) functionality on the surface. HA-CYs particles were further exposed to radical polymerization with NIPAm to obtain temperature responsive HA-CYs-NIPAm hydrogel particles. To acquire magnetic field responsive HA composites, magnetic iron particles were included in HA to form HA-Fe during HA particle preparation. HA-Fe hydrogel particles were also chemically modified. The prepared HA-CYs-NIPAm demonstrated temperature dependent size variations and phase transition temperature. HA-CYs-NIPAm and HA-Fe-CYs particles can be used as drug delivery vehicles. Sulfamethoxazole (SMZ), an antibacterial drug, was used as a model drug for temperature-induced release studies from these particles.     

Modeling of CN-functionalized silica as vehicle for delivery of the chemotherapeutic agent: cisplatin

The adsorption of cisplatin and its complexes, cis-[PtCl(NH₃)₂]⁺ and cis-[Pt(NH₃)₂]²⁺, on a CN-functionalized SiO₂(111) surface has been studied by the atom superposition and electron delocalization method. The adiabatic energy curves for the adsorption of the drug and its complexes on the delivery system were considered. Electronic structure and bonding analyses were also performed. The molecules are adsorbed on the functionalized surface resulting in a major absorption of the cis-[Pt(NH₃)₂]²⁺ complex. The molecule?Csurface interactions are strengthened due to the incorporation of the CN silane group. The most important bonds occur through Pt?CC, Pt?CN and Pt?CSi interactions. Despite the new interactions, the functionalized carrier maintains its matrix properties after adsorption. The remarkable properties may be attributed to the small electronic structure changes in the Si?CCN groups caused by the interaction with neighboring cisplatin molecules and the enhancement in Pt-bonding interactions due to the surface incorporation of the CN silane groups.     

Theoretical study of cisplatin adsorption on silica

The adsorption of cisplatin and its complexes, cis-[PtCl(NH₃)₂]⁺ and cis-[Pt(NH₃)₂]²⁺, on a SiO₂(1 1 1) hydrated surface has been studied by the Atom Superposition and Electron Delocalization method. The adiabatic energy curves for the adsorption of the drug and its products on the delivery system were considered. The electronic structure and bonding analysis were also performed. The molecule-surface interactions are formed at expenses of the OH surface bonds. The more important interactions are the Cl-H bond for cis-[PtCl₂(NH₃)₂] and cis-[PtCl(NH₃)₂]⁺ adsorptions, and the Pt-O interaction for cis-[Pt(NH₃)₂]²⁺ adsorption. The Cl p orbitals and Pt s, p y d orbitals of the molecule and its complexes, and the s H orbital and, the s and p orbitals of the O atoms of the hydrated surface are the main contribution to the surface bonds.     

Effect of interfacial diffusion on microstructure and properties of FePt/B4C multifunctional multilayer composite films

FePt/B₄C multilayer composite films were prepared by magnetron sputtering and subsequent annealing in vacuum. By changing Fe layer thickness of [Fe/Pt]₆/B₄C films, optimal magnetic property (8.8 kOe and remanence squareness is about 1.0) is got in [Fe(5.25 nm)/Pt(3.75 nm)]₆/B₄C sample whose composition is Fe rich and near stoichiometric ratio. The characterizations of microstructure demonstrate that the diffusion of B and C atoms into FePt layer depends strongly on B₄C interlayer thickness. When B₄C interlayer thickness of [Fe(2.625 nm)/Pt(3.75 nm)/Fe(2.625 nm)/B₄C]₆ films is bigger than 3 nm, stable value of grain size (6-6.5 nm), coercivity (6-7 kOe) and hardness (16-20 GPa) is observed. Finally, the multifunctional single FePt/B₄C composite film may find its way to substitute traditional three-layer structure commonly used in present data storage technology.     

Cationic versus Anionic Pillared Layered Substrates: Comparison of the Pillaring Reactions and the Resulting Porosities

Cationic clays and Layered Double Hydroxides (LDHs) are both layeredion exchangers, in which a stable (micro)porosity can be induced via apillaring process. For the cationic clays, the [Zr]-pillaring of hectoritecreates a broad micropore distribution with the maximum at 1.42–2.12nm. The [Al]-equivalent exhibits a narrower distribution, with pores between0.71 and 1.06 nm being dominant. In case of the [Zr]-pillared form a surfacearea of 294 m²/g and a micropore volume of 0.118cm³/g have been obtained. The same reaction on the syntheticlaponite clay reveals a much higher surface area (606 m²/g)and porosity (µPV = 0.336 cm³/g). Forlaponite, extra pores are created in the supermicropore-small mesoporeregion due to the preferential edge-to-face and edge-to-edge stacking of itssmaller sized clay layers.For the pillaring of MgAl- and ZnAl-LDHs with polyoxometalates (POMs),using large organic anions for pre-swelling purposes forms the mostpromising method for the creation of stable pores. It avoids the formationof sidephases, and gives rise to medium(-high) µPVs. Charge density onthe layers forms the key factor, lowering it improves the porositycharacteristics significantly. [Fe(CN)₆]-MgAl-LDHs exhibitmore spectacular properties, with surface areas and µPVs exceedingthose of pillared hectorite. A variation in the charge density via theM ^II/M ^III ratio optimizes theporosity properties. A M ^II/M ^IIIratio of 3.33 results in a SA of 499 m²/g and a µPV of0.177 cc/g. For LDHs, both types of pillars create mainly small micropores,with a diameter smaller than 0.71 nm.     

Magnetization reversal and domains structures in (Co/Ni/Co/Pt) multilayers

Multilayers of [Co/Ni(t_Ni)/Co/Pt]_×4 are investigated for different Ni insertion layer thicknesses. The resulting magnetic properties and magnetic domain structures are compared with [Co/Ni]_×8 multilayers. As determined by magneto-optical Kerr effect microscopy and a vibrating sample magnetometer measurements, all multilayers exhibited a perpendicular magnetic anisotropy. It is found that the nucleation field and magnetic coercivity of [Co/Ni(t)/Co/Pt]_×4 multilayers are lower than (Co/Ni)_×8 and decreased with Ni thickness. Magnetization decay measurements reveal that these multilayers did not show an exponential decay behavior as was observed in rare earth transition metal alloys. Very narrow wires will remain stables for several hours even with an applied magnetic field closer to the coercivity. Insertion of very thin Ni in (Co/Pt) multilayers offers a good way to optimize the magnetic properties of the material and adjust the domain size for nanowire-based devices.     

Laser-induced fluorescence measurements of velocity within a Hall discharge

The results of a study of laser-induced fluorescence velocimetry of neutral and singly ionized xenon in the plume and interior portions of the acceleration channel of a Hall thruster plasma discharge operating at powers ranging from 250 to 725 W are described. Axial ion and neutral velocity profiles for four discharge voltage conditions (100 V, 160 V, 200 V, 250 V) are measured as are radial ion velocity profiles in the near-field plume. Ion velocity measurements of axial velocity both inside and outside the thruster as well as radial velocity measurements outside the thruster are performed using laser-induced fluorescence with nonresonant signal detection on the xenon ion 5d[4]_7/2–6p[3]_5/2 excitation transition while monitoring the signal from the 6s[2]_3/2–6p[3]_5/2transition. Neutral axial velocity measurements are similarly performed in the interior of the Hall thruster using the 6s[3/2]⁰ ₂–6p[3/2]₂transition with resonance fluorescence collection. Optical access to the interior of the Hall thruster is provided by a 1-mm-wide axial slot in the insulator outer wall. While the majority of the ion velocity measurements used partially saturated fluorescence to improve the signal-to-noise ratio, one radial trace of the ion transition was taken in the linear fluorescence region and yields a xenon ion translational temperature between 400 and 800 K at a location 13 mm into the plume. Received: 27 September 2000 / Revised version: 2 March 2001 / Published online: 9 May 2001     

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.     

Ultrathin (CoFe/Pt)n multilayers with tuned magnetic properties

Perpendicular magnetic anisotropy (PMA) has been investigated in ultrathin (CoFe [0.2] nm/Pt [0.2] nm)_n multilayers. The Pt layers show an fcc crystal structure with a preferred [111] orientation. The multilayers with n=3, 4 show PMA in the as-grown state, which can be enhanced by thermal annealing. However, no PMA is observed in the as-grown state with higher repetitions (n>&=5), although it is observed after thermal annealing. For 1=&<n=&<8, the anisotropy energy is around 10⁵ J/m³ for all (CoFe [0.2]/Pt [0.2])_n stacks. The perpendicular anisotropy is related to layer thickness and interface roughness.