Delivery of Liposomal Quantum Dots via Monocytes for Imaging of Inflamed Tissue

Abstract

Quantum dots (QDs), semiconductor nanocrystals, are fluorescent nanoparticles of growing interest as an imaging tool of a diseased tissue. However, a major concern is their biocompatibility, cytotoxicity, and fluorescence instability in biological milieu, impeding their use in biomedical applications, in general, and for inflammation imaging, in particular. In addition, for an efficient fluorescent signal at the desired tissue, and avoiding systemic biodistribution and possible toxicity, targeting is desired. We hypothesized that phagocytic cells of the innate immunity system (mainly circulating monocytes) can be exploited as transporters of specially designed liposomes containing QDs to the inflamed tissue. We developed a liposomal delivery system of QDs (LipQDs) characterized with high encapsulation yield, enhanced optical properties including far-red emission wavelength and fluorescent stability, high quantum yield, and protracted fluorescent decay lifetime. Treatment with LipQDs, rather than free QDs, exhibited high accumulation and retention following intravenous administration in carotid-injured rats (an inflammatory model). QD-monocyte colocalization was detected in the inflamed arterial segment only following treatment with LipQDs. No cytotoxicity was observed following LipQD treatment in cell cultures, and changes in liver enzymes and gross histopathological changes were not detected in mice and rats, respectively. Our results suggest that the LipQD formulation could be a promising strategy for imaging inflammation.

Therapeutic Potential and Main Methods of Obtaining Selenium Nanoparticles

“…Important characteristics for SeNP during their preparation and storage are the concentration, temperature, nature of the biomolecules, and pH of the reaction mixture. For example, spherical SeNP have been proven to have high biological applications, while Se nanowires have high photoconductivity [ 32 , 33 ]. The size of SeNP can determine their antioxidant properties.…”

“…Using biosynthesis or chemical synthesis, SeNP with a hexagonal ring structure and rod-like, spherical, or flower-like shapes can be produced. Spherical SeNP have been used for biological and medicinal purposes [ 37 ], but there are SeNP with other shapes, such as cubic-like, nanorods, nanowires, nanotubes, nanoribbons, and nanoneedles [ 33 ].…”

Strategies for visualizing inflammation

“…Therefore, immunocyte‐mediated targeting by virtue of immune cells or components of immune cells is another emerging approach. For instance, Aizik et al designed a liposomal quantum dot (QD) delivery system, and it was verified that the QD‐laden liposomes could passively target the inflammation region through the endocytosis of circulating monocytes 23 . The encapsulation of QDs not only realized a selective biodistribution, but also elevated the quantum yield (QY) and prolonged the fluorescence decay lifetime under the quenching conditions of the blood and lysosomes, and most importantly, improved the biocompatibility.…”

Hybrid Vesicular Drug Delivery Systems for Cancer Therapeutics

“…The main challenge of their in vivo use is their intrinsic toxicity, which is related to the possible release of heavy metal ions in the blood steam. In addition, they may become quenched due to serum protein adsorption or harsh environments, such as oxidative or acidic conditions . Thus, studies are moving toward resolving the limitations of using drug delivery systems.…”

“…Aizik et al prepared negatively charged quantum dots (CdSe/CdZnS) that were incorporated into the bilayer of cationic liposomes . They proved that the designed system led to enhanced accumulation of the particles in inflamed tissue and fluorescent stability and could be used as a promising highly sensitive drug tracking system.…”