Assembly of Iron Oxide Nanocubes for Enhanced Cancer Hyperthermia and Magnetic Resonance Imaging.

Multiple formulations of iron oxide nanoparticles (IONPs) have been proposed for enhancing contrast in magnetic resonance imaging (MRI) and for increasing efficacy in thermal ablation therapies. However, insufficient accumulation at the disease site and low magnetic performance hamper the clinical application of IONPs. Here, 20 nm iron oxide nanocubes were assembled into larger nanoconstructs externally stabilized by a serum albumin coating.

Enzymatic conversion of magnetic nanoparticles to a non-magnetic precipitate: a new approach to magnetic sensing.

Magnetic sensing utilizes the detection of biomolecule-conjugated magnetic nanoparticles (MNPs). Our new strategy offers a novel approach to magnetic sensing where in situ conversion produces a "loss of signal" in the sensing device. This report demonstrates the enzymatic conversion of Fe3O4 MNPs to a non-magnetic precipitate via reduction by l-ascorbic acid generated by the action of alkaline phosphatase.

Multi-responsive hybrid particles: thermo-, pH-, photo-, and magneto-responsive magnetic hydrogel cores with gold nanorod optical triggers.

The research strategy described in this manuscript harnesses the attractive properties of hydrogels, gold nanorods (Aurods), and magnetic nanoparticles (MNPs) by synthesizing one unique multi-responsive nanostructure. This novel hybrid structure consists of silica-coated magnetic particles encapsulated within a thermo-responsive P(NIPAM-co-AA) hydrogel network on which Aurods are assembled. Furthermore, this research demonstrates that these composite particles respond to several forms of external stimuli (temperature, pH, light, and/or applied magnetic field) owing to their specific architecture.

Synthesis of multifunctional magnetic nanoflakes for magnetic resonance imaging, hyperthermia, and targeting.

Iron oxide nanoparticles (IOs) are intrinsically theranostic agents that could be used for magnetic resonance imaging (MRI) and local hyperthermia or tissue thermal ablation. Yet, effective hyperthermia and high MR contrast have not been demonstrated within the same nanoparticle configuration. Here, magnetic nanoconstructs are obtained by confining multiple, ∼ 20 nm nanocubes (NCs) within a deoxy-chitosan core.

Design maps for the hyperthermic treatment of tumors with superparamagnetic nanoparticles.

A plethora of magnetic nanoparticles has been developed and investigated under different alternating magnetic fields (AMF) for the hyperthermic treatment of malignant tissues. Yet, clinical applications of magnetic hyperthermia are sporadic, mostly due to the low energy conversion efficiency of the metallic nanoparticles and the high tissue concentrations required. Here, we study the hyperthermic performance of commercially available formulations of superparamagnetic iron oxide nanoparticles (SPIOs), with core diameter of 5, 7 and 14 nm, in terms of absolute temperature increase ΔT and specific absorption rate (SAR).

Gold-silver alloy nanoshells: a new candidate for nanotherapeutics and diagnostics.

We have developed novel gold-silver alloy nanoshells as magnetic resonance imaging (MRI) dual T1 (positive) and T2 (negative) contrast agents as an alternative to typical gadolinium (Gd)-based contrast agents. Specifically, we have doped iron oxide nanoparticles with Gd ions and sequestered the ions within the core by coating the nanoparticles with an alloy of gold and silver. Thus, these nanoparticles are very innovative and have the potential to overcome toxicities related to renal clearance of contrast agents such as nephrogenic systemic fibrosis.

Brownian relaxation of interacting magnetic nanoparticles in a colloid subjected to a pulsatile magnetic field.

We have investigated and modeled the effect of interaction among magnetic particles and the magnitude and duration of external applied magnetic field on Brownian relaxation in a colloidal suspension. In the case of interacting magnetic particles, Brownian relaxation depends on the interparticle dipole-dipole interaction, which slows down the overall Brownian relaxation process of magnetic particles in the colloidal suspension. The individual magnetic particle experiences torque when a pulsatile magnetic field is applied.

Cardiovascular impact of manual and automated turns in ICU.

Mechanically ventilated patients in the intensive care unit (ICU) are typically turned manually by nursing staff to reduce the risk of developing ventilator associated pneumonia and other problems in the lungs. However, turning can induce changes in the heart rate and blood pressure that can at times have a destabilizing effect. We report here on the early stage of a study that has been undertaken to measure the cardiovascular impact of manual turning, and compare it to changes induced when patients lie on automated beds that turn continuously.

A comparison of fetal and neonatal heart rate variability at similar post-menstrual ages.

Substantial differences of heart rate variability (HRV) were found between fetuses and prematurely born neonates in the high-frequency band of the power spectrum. The range of post-menstrual ages of the fetuses and neonates were closely matched in this study. Growth of HRV was observed in low-frequency and high-frequency bands, reflecting maturation of the autonomic nervous system.

Change in complexity of fetal heart rate variability.

In a pilot study of fetal heart rate variability using magnetocardiograms it was found that substantial changes occur in complexity as the fetus matures. The self-similarity parameter increased sharply from 26 weeks to 30 weeks gestational age, while the relationship of entropy to timescale reversed during the same period. This suggests that there is distinct maturation of the autonomic nervous system during this period.

Analysis of fetal heart rate variability obtained by magnetocardiography.

Objective: To obtain fetal magnetocardiogram (fMCG) recordings in preterm fetuses in both shielded and unshielded clinical settings.

Methods: Seventeen fMCG recordings were obtained from 6 low-risk fetuses of 26-35 weeks' postmenstrual age. The superconducting quantum interference device biomagnetometer was positioned over the gravid abdomen, and the signals, associated with the bioelectrical activity of the fetal heart, were digitized at a sampling rate of 1 kHz.

Evaluation of the performance of a QRS detector for extracting the heart interbeat RR time series from fetal magnetocardiography.

Fetal magnetocardiography is a useful technique for non-invasive diagnostics of the electrophysiological activity of the fetal heart. The purpose of this study was to acquire fetal magnetocardiograms (FMCG) in a magnetically shielded environment as well as in a high-frequency noise environment, implement a QRS detection algorithm, and evaluate its performance. The FMCG were recorded over a period of 5 minutes at several sensor locations above the pregnant abdomen by second-order SQUID gradiometers.

Monitoring fetal development with magnetocardiography.

Fetal heart rate variability (fHRV) is useful for noninvasive assessment of the status of the autonomic nervous system of the developing fetus. In this pilot study we acquired fetal magnetocardiograms (fMCG) in a magnetically shielded environment. Each recording was of 5-minute duration and was subsequently repeated in a high-frequency noise environment to examine the feasibility of conducting future recordings in clinical environments that lack facilities for magnetic shielding.

Changes in magnetocardiogram patterns of infarcted-reperfused myocardium after injection of superparamagnetic contrast media.

The changes in spatio-temporal patterns of magnetocardiograms were investigated following injection of superparamagnetic iron-oxide (SPIO) nanoparticles using a dog model of ischemia/reperfusion. Acute myocardial infarction was induced by ligation of the left anterior descending coronary in two anesthetized open-chest dogs. Following 60 min coronary occlusion and 30 min reperfusion, dogs were subjected to injections of SPIO at a dose of 0.