Ferromagnetic FePt-Nanoparticles/Polycation Hybrid Capsules Designed for a Magnetically Guided Drug Delivery System

Abstract

The present Article describes the synthesis of ferromagnetic capsules approximately 330 nm in diameter with a nanometer-thick shell to apply to magnetic carriers in a magnetically guided drug delivery system. The magnetic shell of 5 nm in thickness is a nanohybrid, composed of ordered alloy FePt nanoparticles of approximately 3-4 nm in size and a polymer layer of a cationic polyelectrolyte, poly(diaryldimethylammonium chloride) (PDDA). The magnetic capsules have an excellent capacity for carrying medical drugs and genes. Surface-modified silica particles with PDDA were used as a template for the capsules. FePt nanoparticles were deposited on the PDDA-modified silica particles through a polyol method followed by dissolving the silica particles with a NaOH solution, resulting in the formation of the magnetic capsules as the final product. A three-dimensional hollow structure is maintained by the nanohybrid shell. The FePt-nanoparticles/PDDA nanohybrid shell also exhibits a ferromagnetic feature at room temperature because the FePt nanoparticles of an ordered-alloy phase are formed with the aid of PDDA despite the small size (3-4 nm).

Size-tunable drug-delivery capsules composed of a magnetic nanoshell

“…1A–C). Our previous report demonstrated that FePt nanoparticles accumulate on organic compounds adsorbed on the surface of silica particles 18 confirming that the surface of the silica template particles treated with 1 or 5 wt% PDDA solution were not entirely covered with PDDA molecules, and that FePt nanoparticles accumulated only at the PDDA molecules adsorbed on the silica surface. This means that the FePt nanoparticles were selectively grown on the PDDA layer.…”

“…Our previous papers demonstrated two types of FePt magnetic capsules with thinner shells (d = 5–10 nm) compared with previously reported magnetic capsules 1 - 13 , 18 - 20 Scheme 1. shows the fabrication process for these two types of FePt magnetic capsules and representative transmission electron microscopy (TEM) images.…”

“…The higher magnetocrystalline anisotropy constant means that the thickness of the shells can be reduced without any deterioration of the magnetic response. Although the total sizes of the two types of FePt capsules in our previous work were too large (330–340 nm) for them to be used in a nano-DDS, 18 , 19 capsular size could be controlled by varying the size of the silica template particles. In addition, shell thickness could be controlled by changing the amount of FePt nanoparticles accumulated on the surface of the PDDA-modified silica template particles because our FePt-nanoparticle/PDDA hybrid shell was composed of FePt nanoparticles and a single layer of PDDA, and the FePt network shell was composed of only FePt alloy.…”

“…shows the fabrication process for these two types of FePt magnetic capsules and representative transmission electron microscopy (TEM) images. The first type of FePt magnetic capsule was an inorganic-organic hybrid capsule that was fabricated by growing ordered alloy FePt nanoparticles on silica template particles with an anionic surface that had been modified with a cationic polymer, poly(diallyldimethylammonium chloride) (PDDA), and then dissolving the silica template particles from the FePt-nanoparticle/PDDA/silica particles by using NaOH aqueous solution 18 . This hybrid shell was composed of 3 to 5 nm of FePt nanoparticles and a single layer of PDDA.…”

Effect of functionalization on positional ordering of 3 nm FePt nanoparticles: Langmuir–Blodgett monolayer

“…The possibility to synthesize molecules with desired structure and functionality in conjunction with a sophisticated thin film deposition technology enables the production of electrically, optically, magnetically and biologically active components on a nanometer scale [5,6]. A thin film can be deposited on a solid substrate by various techniques such as thermal evaporation, sputtering, electro-deposition, molecular beam epitaxy, adsorption from solution, Langmuir-Blodgett (LB) technique, and self-assembly.…”