Systemic Administration of Polyelectrolyte Microcapsules: Where Do They Accumulate and When? In Vivo and Ex Vivo Study

Abstract

Multilayer capsules of 4 microns in size made of biodegradable polymers and iron oxide magnetite nanoparticles have been injected intravenously into rats. The time-dependent microcapsule distribution in organs was investigated in vivo by magnetic resonance imaging (MRI) and ex vivo by histological examination (HE), atomic absorption spectroscopy (AAS) and electron spin resonance (ESR), as these methods provide information at different stages of microcapsule degradation. The following organs were collected: Kidney, liver, lung, and spleen through 15 min, 1 h, 4 h, 24 h, 14 days, and 30 days after intravenous injections (IVIs) of microcapsules in a saline buffer at a dosage of 2.5 × 109 capsule per kg. The IVI of microcapsules resulted in reversible morphological changes in most of the examined inner organs (kidney, heart, liver, and spleen). The capsules lost their integrity due to degradation over 24 h, and some traces of iron oxide nanoparticles were seen at 7 days in spleen and liver structure. The morphological structure of the tissues was completely restored one month after IVI of microcapsules. Comprehensive analysis of the biodistribution and degradation of entire capsules and magnetite nanoparticles as their components gave us grounds to recommend these composite microcapsules as useful and safe tools for drug delivery applications.

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

“…Magnetic nanoparticles are considered as T2 contrast agents because they reduced the spin-spin relaxation time [51]. For this purpose, the experimental work carried out to determine the extent to which these particles would enhance the contrast of an MRI image through T1 and T2 sequences.…”

Biodegradable Microcapsules Loaded with Nerve Growth Factor Enable Neurite Guidance and Synapse Formation

“…The polyelectrolyte microcapsules fabricated by the LbL-technique have been demonstrated as an efficient delivery system for targeting different tissue and cell types. The suitability for this type of carriers has been confirmed in animals in vivo through either systemic application [ 44 , 45 , 46 , 47 ] or during local injections of the microcapsule suspension into the targeted tissue [ 24 ]. However, there have been only a few attempts to explore the use of biodegradable LbL-microcapsules in the central nervous system, especially with respect to the brain where multiple and distinct cell types are densely inter-connected with high spatial specificity.…”

Micro‐Bio‐Chemo‐Mechanical‐Systems: Micromotors, Microfluidics, and Nanozymes for Biomedical Applications

“…Intriguingly, for in vitro studies, artificial glass capillary was performed with the widefield fluorescence microscope employment. [355] With the LbL assembly, both fluorescence and response to the magnetic field properties were achieved, separating layers with corresponding components by polyelectrolyte bilayers to prevent quenching. The magnetic field can effectively retain the microcapsules, still, in vitro studies explained that the capsules did not attach to the capillary wall, but they remain on the vessel wall after switching the magnetic field off in vivo, in a rat mesentery microvessel.…”