Biocompatibility, Pharmaceutical and Biomedical Applications L. Harivardhan Reddy,†,‡ Jose ́ L. Arias, Julien Nicolas,† and Patrick Couvreur*,† †Laboratoire de Physico-Chimie, Pharmacotechnie et Biopharmacie, Universite ́ Paris-Sud XI, UMR CNRS 8612, Faculte ́ de Pharmacie, IFR 141, 5 rue Jean-Baptiste Cleḿent, F-92296 Chat̂enay-Malabry, France Departamento de Farmacia y Tecnología Farmaceútica, Facultad de Farmacia, Campus Universitario de Cartuja s/n, Universidad de Granada, 18071 Granada, Spain ‡Pharmaceutical Sciences Department, Sanofi, 13 Quai Jules Guesdes, F-94403 Vitry-sur-Seine, France

Magnetic nanoparticles: design and characterization, toxicity and biocompatibility, pharmaceutical and biomedical applications.

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Superparamagnetic iron oxide nanoparticles (SPIONs): Development, surface modification and applications in chemotherapy

Magnetic sensors can be classified according to whether they measure the total magnetic field or the vector components of the magnetic field. The techniques used to produce both types of magnetic sensors encompass many aspects of physics and electronics. Here, we describe and compare most of the common technologies used for magnetic field sensing. These include search coil, fluxgate, optically pumped, nuclear precession, SQUID, Hall-effect, anisotropic magnetoresistance, giant magnetoresistance, magnetic tunnel junctions, giant magnetoimpedance, magnetostrictive/piezoelectric composites, magnetodiode, magnetotransistor, fiber optic, magnetooptic, and microelectromechanical systems-based magnetic sensors. The usage of these sensors in relation to working with or around Earth's magnetic field is also presented

Magnetic sensors and their applications

Nanostructures have attracted huge interest as a rapidly growing class of materials for many applications. Several techniques have been used to characterize the size, crystal structure, elemental composition and a variety of other physical properties of nanoparticles. In several cases, there are physical properties that can be evaluated by more than one technique. Different strengths and limitations of each technique complicate the choice of the most suitable method, while often a combinatorial characterization approach is needed. In addition, given that the significance of nanoparticles in basic research and applications is constantly increasing, it is necessary that researchers from separate fields overcome the challenges in the reproducible and reliable characterization of nanomaterials, after their synthesis and further process (e.g. annealing) stages. The principal objective of this review is to summarize the present knowledge on the use, advances, advantages and weaknesses of a large number of experimental techniques that are available for the characterization of nanoparticles. Different characterization techniques are classified according to the concept/group of the technique used, the information they can provide, or the materials that they are destined for. We describe the main characteristics of the techniques and their operation principles and we give various examples of their use, presenting them in a comparative mode, when possible, in relation to the property studied in each case.

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Characterization techniques for nanoparticles: comparison and complementarity upon studying nanoparticle properties

A targeted drug delivery system is the need of the hour. Guiding magnetic iron oxide nanoparticles with the help of an external magnetic field to its target is the principle behind the development of superparamagnetic iron oxide nanoparticles (SPIONs) as novel drug delivery vehicles. SPIONs are small synthetic γ-Fe2O3 (maghemite) or Fe3O4 (magnetite) particles with a core ranging between 10 nm and 100 nm in diameter. These magnetic particles are coated with certain biocompatible polymers, such as dextran or polyethylene glycol, which provide chemical handles for the conjugation of therapeutic agents and also improve their blood distribution profile. The current research on SPIONs is opening up wide horizons for their use as diagnostic agents in magnetic resonance imaging as well as for drug delivery vehicles. Delivery of anticancer drugs by coupling with functionalized SPIONs to their targeted site is one of the most pursued areas of research in the development of cancer treatment strategies. SPIONs have also demonstrated their efficiency as nonviral gene vectors that facilitate the introduction of plasmids into the nucleus at rates multifold those of routinely available standard technologies. SPION-induced hyperthermia has also been utilized for localized killing of cancerous cells. Despite their potential biomedical application, alteration in gene expression profiles, disturbance in iron homeostasis, oxidative stress, and altered cellular responses are some SPION-related toxicological aspects which require due consideration. This review provides a comprehensive understanding of SPIONs with regard to their method of preparation, their utility as drug delivery vehicles, and some concerns which need to be resolved before they can be moved from bench top to bedside.

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Superparamagnetic iron oxide nanoparticles: magnetic nanoplatforms as drug carriers

The microwave response of the dc quasiparticle tunneling current in Josephson tunnel junctions, where the Josephson current is suppressed by an external magnetic field, has been studied quantitatively in order to clarify its characteristics as a probe for the measurement of the junction capacitance. Extensive experiments for both small and long junctions are carried out for distinguishing between microwave behaviors of lumped and distributed constant junctions. It is shown that the observed voltage dependence of the dc quasiparticle tunneling current modified by an applied rf field is in good agreement with a theoretical result which takes into account the influence of the microwave circuit connected to the junction. The comparison between theory and experiment gives the magnitude of the internal rf field in the junction. Together with the applied rf field, this internal rf field leads to the junction rf impedance which is dominated by the junction capacitance in our experimental condition. In the case of lumped junctions, this experimental rf impedance is in reasonable agreement with the theoretical one with the junction capacitance estimated from the Fiske step of the distributed junction fabricated on the same substrate; the obtained ratio of the experimental impedance to the theoretical one is approximately 0.6–1.7. In the case of distributed junctions, however, experimental values of their characteristic impedances are approximately 0.2–0.3 of theoretical values calculated by assuming the one‐dimensional junction model and taking account of the standing‐wave effect in the junction.

Capacitance measurement of Josephson tunnel junctions with microwave‐induced dc quasiparticle tunneling currents

The effects of the kinetic inductance of superconducting thin electrodes on the basic parameters of a flux-flow-type Josephson amplifier (FFA) are studied theoretically. It is shown that performance of the FFA can be improved considerably if the kinetic inductance is utilized. A preliminary experiment confirms the theoretical result.

Effects of Kinetic Inductance on the Performance of a Flux-Flow-Type Josephson Amplifier

Two methods are proposed in order to improve the voltage modulation depth of high-T/sub c/ DC SQUIDs in the case of large inductances. One is a damping resistance parallel to the inductance, and the other is a new SQUID using three junctions, which we call 3J-SQUID. Numerical simulation shows the usefulness of the present method. Moreover. It is shown that the improvement of the voltage modulation depth results in the improvement of magnetic flux noise in the white noise region. Therefore, the present method will enable the use of large inductances. The usefulness of the present method is also confirmed partly by experimental results. >

Method for improving voltage modulation depth of high T/sub c/ DC SQUID with large inductance

We studied the performance of a magnetometer composed of a high T c SQUID and a large pickup coil. For the pickup coil, we consider the coil made of a cooled Cu wire or an HTS superconductor tape. A magnetometer was designed for geophysical measurement using transient electromagnetic method. The theoretical field noise of the magnetometer was 0.2–1 pT/Hz 1/2 at f  = 10 Hz, and 55 fT/Hz 1/2 for f  > 200 Hz when the pickup coil of 100 mm in diameter and of N  = 50 turns was used. Preliminary experimental results using the pickup coil made of the HTS Bi-tape reasonably agreed with the theoretical prediction.

Keiji Enpuku

Papers

Capacitance measurement of Josephson tunnel junctions with microwave‐induced dc quasiparticle tunneling currents

Effects of Kinetic Inductance on the Performance of a Flux-Flow-Type Josephson Amplifier

Method for improving voltage modulation depth of high T/sub c/ DC SQUID with large inductance

Performance of HTS SQUID coupled to cooled-Cu/superconductor pickup coil

Biological immunoassay with high Tc superconducting quantum interference device (SQUID) magnetometer