Iron-Loaded Magnetic Nanocapsules for pH-Triggered Drug Release and MRI Imaging

Abstract

Magnetic nanocapsules were synthesized for controlled drug release, magnetically assisted delivery, and MRI imaging. These magnetic nanocapsules, consisting of a stable iron nanocore and a mesoporous silica shell, were synthesized by controlled encapsulation of ellipsoidal hematite in silica, partial etching of the hematite core in acid, and reduction of the core by hydrogen. The iron core provided a high saturation magnetization and was stable against oxidation for at least 6 months in air and 1 month in aqueous solution. The hollow space between the iron core and mesoporous silica shell was used to load anticancer drug and a T1-weighted MRI contrast agent (Gd-DTPA). These multifunctional monodispersed magnetic “nanoeyes” were coated by multiple polyelectrolyte layers of biocompatible poly-l-lysine and sodium alginate to control the drug release as a function of pH. We studied pH-controlled release, magnetic hysteresis curves, and T1/T2 MRI contrast of the magnetic nanoeyes. They also served as MRI contrast agents with relaxivities of 8.6 mM–1 s–1 (r1) and 285 mM–1 s–1 (r2).

Photo-crosslinked natural polyelectrolyte multilayer capsules for drug delivery

“…Although the drug release rate is in our case much faster and less easy to control as in case of pH triggered release [39] it provides a novel path to deliver drugs. We would like to point out, that our approach is especially interesting for cases, where the drug delivery is necessary, but no clear pH gradient is present.…”

“…We would like to point out, that our approach is especially interesting for cases, where the drug delivery is necessary, but no clear pH gradient is present. In such cases a diffusion dependent release might be better than a delivery system requiring a alkaline pH [39], which is present in parts of the human or cellular stomach systems.…”

Guidable Thermophoretic Janus Micromotors Containing Gold Nanocolorifiers for Infrared Laser Assisted Tissue Welding

“…These particles and capsules can be guided by rare earth magnets within blood and tissue fluids of damaged and cut meat samples, and the meat can be fused using near infrared laser. The utilized gold and magnetic nanoparticles are biocompatible, as they are already used as magnetic resonance imaging contrast agents, while the used polyelectrolytes are harmless in complexes (PEM is such a complex) 17, 18, 19. The structural buildup of the Janus particles and capsules is displayed in Scheme 1 .…”

A Fibrous Localized Drug Delivery Platform with NIR-Triggered and Optically Monitored Drug Release

“…15 Therefore, the external-field triggering and real-time monitoring of drug pharmacokinetics in a timely manner are considered as a crucial approach to maintaining suitable drug concentration in blood and ensuring sufficient therapeutic efficacy for highly varied individuals. 16 …”