Magnetic Colloidal Particles in Combinatorial Thin-Film Gradients for Magnetic Resonance Imaging and Hyperthermia

Abstract

A stable oil-in-water (O/W) magnetic emulsion was prepared by the emulsification of organic ferrofluid in an aqueous media, and its theranostic applications were investigated. The synthesis and characterization of the organic ferrofluid were carried out comprising of superparamagnetic maghemite nanoparticles with oleic acid coating stabilized in octane. Both exhibit spherical morphology with a mean size of 6 nm and 200 nm, respectively, as determined by TEM. Thermogravimetric analysis was carried out to determine the chemical composition of the emulsion. The research work described here is novel and elaborates the fabrication of thin-film gradients with 5, 10, 15, and 20 bilayers by layer-by-layer technique using polydimethyl diallyl ammonium chloride (PDAC) and prepared magnetic colloidal particles. The thin-film gradients were characterized for their roughness, morphology, and wettability. The developed gradient films and colloids were explored in magnetic resonance imaging (MRI) and hyperthermia. T1- and T2-weighted images and their corresponding signal intensities were obtained at 1.5 T. A decreasing trend in signal intensities with an increase in nanoparticle concentration in colloids and along the gradient was observed in T2-weighted images. The hyperthermia capability was also evaluated by measuring temperature rise and calculating specific absorption rates (SAR). The SAR of the colloids at 259 kHz, 327 kHz, and 518 kHz were found to be 156 W/g, 255 W/g, and 336 W/g, respectively. The developed magnetic combinatorial thin-film gradients present a significant potential for the future efficient simultaneous diagnostic and therapeutic bioapplications.

Aminodextran Coated CoFe2O4 Nanoparticles for Combined Magnetic Resonance Imaging and Hyperthermia

“…The shortening of T2 relaxation is caused by the functionalization of nanoparticles by aminodextran coating that lessens particle agglomeration by increasing inter-particle spacing as apparent from Figures 5 and 6. The signal intensity of T2 images decreases with an increase in the iron concentrations and these results are in agreement with previously reported literature of MRI data [32]. A higher negative contrast was generated by specimens with higher iron concentrations.…”

“…The images revealed that there is no effect of polymer coating on the nanoparticle crystallite size which leads to the agglomeration of the coated sample particles. The aggregation due to the magnetic and dipolar interactions between the particles which results in wide hydrodynamic size distribution ( Figure S4) and agreement with previously reported data [32]. SEM and TEM images are also consistent in terms of aggregation of the samples, independent of AMD-coating.…”

Magnetic Nanoparticles: From Synthesis to Theranostic Applications

“…127 Heating efficiency of magnetic colloidal nanoparticles emulsified by sodium dodecyl sulphate (SDS) aqueous solution was also evaluated, showing significant potential for therapeutic applications. 128 Water-soluble magnetite Fe 3 O 4 nanoparticles coated by Eudragit E100 (amino methacrylate copolymer) encapsulating Doxorubicin drug were explored for hyperthermia. The specific absorption rate values were also calculated and estimated to be 2.41, 2.71, and 4.28 W/g at the frequency of 259, 327, and 518 kHz and magnetic field strength of 22, 17, and 23 mT, respectively.…”

Magnetic Polymer Colloids for Ultrasensitive Molecular Imaging

“…Conventional techniques for cellular imaging through MRI involve a sample preparation regimen where cell samples are mixed with different concentrations of a known contrast agent and placed inside agarose pockets before imaging. A gradient thin film capable of producing a significant contrast difference along the gradient will eliminate the need for such sample preparation steps and allow for a simple and quick surface-based imaging method (Khizar et al 2020). Thin film gradients using the layer-by-layer technique which can be a promising technique in the future for disposable lab-on-chip as a dipstick approach for ultrasensitive molecular imaging of bioanalytes.…”

“…The proposed materials chip is composed of a gradient thin film of colloidal core-shell magnetic nanoparticles that serve as exogenous contrast agents to generate a negative contrast in aqueous environments in an MRI (Khizar et al 2020). The unique core-shell morphology of these colloids coupled with adequately tailored magnetic properties can significantly increase the signal-to-noise ratio and consequently, the sensitivity of the MR images.…”