Magnetic Heating of Iron Oxide Nanoparticles and Magnetic Micelles for Cancer Therapy

Abstract

The inclusion of magnetic nanoparticles into block copolymer micelles was studied towards the development of a targeted, magnetically triggered drug delivery system for cancer therapy. Herein, we report the synthesis of magnetic nanoparticles and poly(ethylene glycol-b-caprolactone) block copolymers, and experimental verification of magnetic heating of the nanoparticles, self-assembly of the block copolymers to form magnetic micelles, and thermally-enhanced drug release. The semicrystalline core of the micelles melted at temperatures just above physiological conditions, indicating that they could be used to release a chemotherapy agent from a thermo-responsive polymer system. The magnetic nanoparticles were shown to heat effectively in high frequency magnetic fields ranging from 30–70 kA/m. Magnetic micelles also showed heating properties, that when combined with a chemotherapeutic agent and a targeting ligand could be developed for localized, triggered drug delivery. During the magnetic heating experiments, a time lag was observed in the temperature profile for magnetic micelles, likely due to the heat of fusion of melting of polycaprolactone micelle cores before bulk solution temperatures increased. Doxorubicin, incorporated into the micelles, released faster when the micelles were heated above the core melting point.

Synthesis, characterization, and antimicrobial activity of an ampicillin-conjugated magnetic nanoantibiotic for medical applications

“…The MNPs have a face-centered cubic crystal structure with a lattice constant (a) of 8.38 Å, and our results agree in value, with a =8.39 Å. 44 The mean grain size was calculated using the Debye-Scherrer formula, as shown in Equation 2. where D is the mean grain size, k is the Sherrer constant (0.89), λ is the X-ray diffraction wavelength (0.15418 nm), θ is the Bragg diffraction angle in degrees, and β (in radians) is the full width at half maximum intensity. The diffraction peak that corresponds to the lattice plane (311) at 2θ =35.4° was used for these calculations because this peak was well-resolved, and interferences were not detected.…”

Modulation of Interparticle Interactions and Specific Absorption Rate in Magnetomicelles through Changes in the Molecular Weight of the Hydrophobic Polymer Block

“…This delay in temperature increase observed was attributed to PCL melting, which prevents the temperature of the sample from increasing. [ 3 ] The lack of this delay in our measurements is an indication that melting did not take place a short time after the fi eld was applied and it was in this period of time that the slope of the curves was measured for SAR determination. The SAR measurements show that as the PCL molecular weight increases, the SAR decreases.…”

“…[1][2][3] When used as agents for MFH treatment or magnetically triggered DDV, magnetomicelles are subjected to alternating magnetic fi elds, which induce motion of the magnetic dipoles, which, in turn, results in heat dissipation. [3][4][5] Generally, magnetomicelles are prepared using amphiphilic block copolymers that self-assemble in the form of micelles in an aqueous solution and magnetic nanoparticles with a hydrophobic coating, which preferentially partition to the core of the micelles. For biomedical applications, block copolymers that are biocompatible and sometimes biodegradable are necessary and are typically combined with iron oxide nanoparticles (IONP) because they are considered safe for use in the human body.…”

Nanotoxicity of Inert Materials: The Case of Gold, Silver and Iron

“…This will localize nanoparticles in this region when they reach with blood circulation. Another strategy is to use targeting (140)(141)(142). IONP based hyperthermia is utilized for controlling the release of the drug from the temperature sensitive micelles due to phase change in micelles.…”