PEGylation of Dendronized Gold Nanoparticles Affects Their Interaction with Thrombin and siRNA

The use of nonviral carriers based on nanomaterials is a promising strategy for modern gene therapy aimed at protecting the genetic material against degradation and enabling its efficient cellular uptake. To improve the effectiveness of nanocarriers in vivo, they are often modified with poly(ethylene glycol) (PEG) to reduce their toxicity, limit nonspecific binding by proteins in the bloodstream, and extend blood half-life. Thus, the selection of an appropriate degree of surface PEGylation is crucial to preserve the interaction of nanoparticles with the genetic material and to ensure its efficient transport to the site of action. Our research focuses on the use of innovative gold nanoparticles (AuNPs) coated with cationic carbosilane dendrons as carriers of siRNA. In this study, using dynamic light scattering and zeta potential measurements, circular dichroism, and gel electrophoresis, we investigated dendronized AuNPs modified to varying degrees with PEG in terms of their interactions with siRNA and thrombin to select the most promising PEGylated carrier for further research.

Effect of PEGylation on the biological properties of cationic carbosilane dendronized gold nanoparticles

Heterofunctionalized gold nanoparticles (AuNPs) were obtained in a one pot reaction of gold precursor with cationic carbosilane dendrons (first to third generations, 1-3G) and (polyethylene)glycol (PEG) ligands in the presence of a reducing agent. The final dendron/PEG proportion on AuNPs depends on the initial dendron/PEG ratio (3/1, 1/1, 1/3) and dendron generation. AuNPs were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), ultraviolet spectroscopy (UV-VIS), thermogravimetric analysis (TGA), nuclear magnetic resonance (¹H NMR) and zeta potential (ZP). Several assays have been carried out to determine the relevance of PEG/dendron ratio and dendron generation in the biomedical properties of PEGylated AuNPs and the results have been compared with those obtained for non-PEGylated AuNPs. Finally, analyses of PEG recognition by anti-PEG antibodies were carried out. In general, haemolysis, platelet aggregation and toxicity were reduced after PEGylation of AuNPs, the effect being dependent on dendron generation and dendron/PEG ratio. Dendron generation determines the exposure of PEG ligand and the interaction of this ligand with AuNPs environment. On the other hand, increasing PEG proportion diminishes toxicity but also favors interaction with antibodies.

[Inflammatory processes in the pathogenesis of acute coronary syndromes]

Cardiovascular diseases, including acute coronary syndromes (ACS), are one of the most serious problems of modern medicine and therefore every year 4 million Europeans have died. It is now believed that elevated levels of inflammatory factors in the blood promotes the development cardiovascular events and chronic inflammation plays a key role in the pathogenesis of atherosclerosis. Intensively conducted research in many centers in the world can confirm the desirability of introducing anti-inflammatory therapy to standard drug therapy. The balance between pro- and anti-inflammatory processes affect the risk of developing ACS.

[The inflammatory processes in atherogenesis]

Atherogenesis is the process of atherosclerotic plaque formation, leading to coronary artery heart disease. This process involves immune cells, mainly T and B cells, monocytes and macrophages. The process of atherogenesis is induced by inflammatory damage of endothelial cells. The characteristic construction features of the atherosclerotic plaque is a predisposing factor for acute coronary syndromes. The accumulation of inflammatory cells in the artery inner membrane enhances the local inflammatory process due to the secretion of reactive oxygen species, inflammatory cytokines and metalloproteinases, which accelerate the development of atherosclerotic lesions in the arteries. In chronic inflammation of endothelial cells, which is atherosclerosis, there is a decrease in the concentration of elastin and collagen as a result of the increased apoptosis of smooth muscle cells of the intima. This reduces the integrity and strength of the fibrous cap that covers a layer of thrombogenic plaque from contact with blood elements. Permanent inflammation promotes the formation of necrotic core, composed of dead smooth muscle cells, macrophages and foam cells formed by phagocytosis of oxidized lipid molecules. The thin fibrous cap and a large necrotic core are the cause of plaque rupture and thrombus formation within the coronary artery.

Structure-property relationships of a tetrapyrrolidinyl PNP-lariat ether and its complexes with potassium, sodium, and silver cations

Spectral properties of the tetrapyrrolidinyl PNP-lariat ether, L, and its complexes with K+, Na+, and Ag+ were investigated. Crystal structures of L and its complex with potassium iodide [KL]I were determined. Protonation constants of the ligand and formation constants of its complexes with Ag+, K+, and Na+ in aqueous solutions were determined. 1H NMR, 31P NMR, FTIR, and ESIMS spectra as well as potentiometric measurements indicate that complexation of Ag+ involves participation of the polyether oxygen donors and the endocyclic nitrogen atom of the cyclophosphazene ring. On the other hand, for complexation of K+ and Na+, only polyether oxygen atoms are involved. The latter conclusion is confirmed in the solid-state structure of the [KL]I complex.

Occupational exposure to external ionising radiation in Poland, 1999

In 1999 about 6208 radiation workers from 389 departments were monitored by CLOR in Poland. The distribution of annual personal doses shows that 85% of controlled workers received doses below the MDL (0.4 mSv) and about 97% controlled workers received doses below 5 mSv. Doses higher than 50 mSv were received by three operators of industrial radiography units. The radiation workers under control are divided into four main work sectors: nuclear industry, research and education, medicine, and general industry. The average annual dose for all workers in each particular sector was 0.22 mSv, 0.22 mSv, 0.30 mSv and 0.80 mSv, respectively. The average annual dose for the entire monitored population was 0.47 mSv. The average annual dose in each particular sector for number of workers receiving E > 0, i.e. Hp(10) > or = 0.4 mSv, amounted to 1.78 mSv, 2.03 mSv, 1.88 mSv and 4.85 mSv, respectively. The average annual dose for the full number of workers receiving E > 0 was 3.21 mSv. This paper contains the detailed analysis of occupational exposure. The distributions of annual occupational exposure in different work sectors are also given.