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.
Highlights
Novel drug delivery systems have been in the focus of research in bio-nanotechnology in the past decades
If a delivery system represents a sort of vesicle in order to make it visible and addressable, these vesicles should incorporate nanoparticles such as magnetite nanoparticles, which can be seen by full-body imaging techniques such as magnetic resonance imaging (MRI)
Magnetite distributed in liver leads to a decrease in the MR signal intensity in the region of interest (ROI) in the T1 weighted MR images (Figure 3a)
Summary
Novel drug delivery systems have been in the focus of research in bio-nanotechnology in the past decades. Substantial progress in biomedicine and applied chemistry resulted in the development of reasonably effective delivery systems aimed to bring bioactive compounds via chemical targeting to a particular site of the body, organs and tissues. The major demand in the area is how to direct the vesicles to the tumor site, which remains challenging due to side effects. Recent developments in nanobiotechnology have made an essential contribution, as they deal with fabrication of constructs enabling multimodal functioning, carrying bioactive molecules and being visible and addressable externally. If a delivery system represents a sort of vesicle in order to make it visible and addressable, these vesicles should incorporate nanoparticles such as magnetite nanoparticles, which can be seen by full-body imaging techniques such as magnetic resonance imaging (MRI)
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