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

Abstract

Nano-sized FePt capsules with two types of ultrathin shell were fabricated using a template method for use in a nano-scale drug delivery system. One capsule was composed of an inorganic-organic hybrid shell of a water-soluble polymer and FePt nanoparticles, and the other capsule was composed of a network of fused FePt nanoparticles. We demonstrated that FePt nanoparticles selectively accumulated on the polymer molecules adsorbed on the template silica particles, and investigated the morphologies of the particle accumulation by changing the concentration of the polymer solution with which the template particles were treated. Capsular size was reduced from 340 to less than 90 nm by changing the size of the silica template particles, and the shell thickness was controlled by changing the amount of FePt nanoparticles adsorbed on the template particles. The hybrid shell was maintained by the connection of FePt nanoparticles and polymer molecules, and the shell thickness was 10 nm at the maximum. The FePt network shell was fabricated by hydrothermal treatment of the FePt/polymer-modified silica composite particles. The FePt network shell was produced from only the FePt alloy, and the shell thickness was 3 nm. Water-soluble anti-cancer drugs could be loaded into the hollow space of FePt network capsules, and lipid-coated FePt network capsules loaded with anti-cancer drugs showed cellular toxicity. The nano-sized capsular structure and the ultrathin shell suggest applicability as a drug carrier in magnetically guided drug delivery systems.

Magnetic force microscopy

“…In particular, different configurations have been engineered where vesicles are coupled with magnetic nanomaterials (e.g., Fe based nanoshells or MNPs) to be employed as magnetically guided nanocarries 74 , 75 . To this aim, referring to the inclusion of Fe based MNPs in niosomes, the Fe entrapment efficiency (e.e.)…”

In vitro study of the interaction of heregulin-functionalized magnetic–optical nanorods with MCF7 and MDA-MB-231 cells

“…The anisotropic nature of Fe-Au nanorods also renders them potential agents for cell destruction therapy, where heating acting on internalized particles have been shown to induce apoptosis. The polycrystalline nature of the Fe segment 20 makes these rods magnetically soft; yet their Ms is >10× higher than of SPIONs, which are widely used as MRI contrast agents. 36 Pure Fe NPs require >20× smaller concentration to generate the same amount of heat as SPIONs of similar size 37 and hence are more suitable for magnetic hyperthermia.…”

“…Magnetic nanoparticles developed for drug delivery or theranostic applications, such as FePt capsules 20 and Fe 2 O 3 tubes, 21 may also be optimized for magnetic tweezers applications like those presented in this article. Other potential 25 candidates are the soft composite materials with programmable shape changes: Stripes that twist or bend, 22 and tubes that collapse upon exposure to weak magnetic fields 23 can be further exploited for their use as magnetic tweezers probes.…”

“…It is now possible to design and synthesize multi-segmented and multi-layered nanoparticles of defined composition from two or more inorganic, organic, or biological materials. 1,2 Novel nanoparticles have been developed for biomedical and biotechnological applications where they play an important role in in 20 vitro diagnostics, in vivo imaging, vaccines, and therapeutics, due to their strong interaction with electromagnetic fields and ability to interact with cells and biomolecules. 3 Of particular interest are multifunctional nanoparticles that act as highly sensitive contrast agents for cancer diagnosis as well as carriers of small molecule or biomolecular therapeutic agents.…”

“…29 According to Bell's model, the off-rate of a single, specific intermolecular interaction depends on the externally-applied constant force F [1] where k off,0 is the dissociation rate of the interaction in the absence of an external force and f is the scaling force, characteristic of that interaction. 30 This model implies that weak, non-covalent bonds have a limited lifetime and will break 20 under any level of force if pulled on for a sufficient time period. An extension of this model is proposed 31 for multiple parallel bonds of the same type where the off-rate also depends on the number of bonds, n [2]…”