Improved efficacy and safety of low doses of benznidazole-loaded multiparticulate delivery systems in experimental Chagas disease therapy

Benznidazole (BZ) is a first-line drug for the treatment of Chagas disease; however, it presents several disadvantages that could hamper its therapeutic success. Multiparticulate drug delivery systems (MDDS) are promising carriers to improve the performance of drugs. We developed BZ-loaded MDDS intended for improving Chagas disease therapy. To assess their efficacy and safety, Trypanosoma (T) cruzi infected BALB/c mice were orally treated with free BZ or BZ-MDDS at different regimens (doses of 50 and 100 mg/kg/day, administered daily or at 2- or 5-days intervals) and compared with infected non-treated (INT) mice. At 100 mg/kg/day, independent of the administration regimen, both treatments were able to override the parasitemia, and at 50 mg/kg/day significantly reduced it compared to INT mice. BZ-MDDS at a dose of 100 mg/kg/day administered every 5 days (BZ-MDDS 100-13d) induced the lowest cardiac parasite load, indicating an improved efficacy with lower total dose of BZ when loaded to the MDDS. Reactive oxygen species produced by leukocytes were higher in INT and mice treated with BZ at 50 mg/kg/day compared to 100 mg/kg/day, likely because of persistent infection. BZ-MDDS treatments markedly reduced heart and liver injury markers compared to INT mice and those receiving the standard treatment. Therefore, BZ-MDDS exhibited enhanced activity against T. cruzi infection even at lower doses and reduced administration frequency compared to free BZ while increasing the treatment safety. They likely avoid undesired side effects of BZ by keeping a sustained concentration, avoiding plasmatic drug peaks. BZ-MDDS evidenced significant improvements in experimental Chagas disease treatment and can be considered as a potential improved therapeutic alternative against this illness.

Effect of pH adjustment and ratio of oppositely charged polymers on the mechanistic performance and sustained release of volatile perfume in interpolyelectrolyte complex microcapsules

In this study, volatile perfume was encapsulated in microcapsules (MCs) via interpolyelectrolyte complexes (IPECs) of oppositely charged polymers, with high encapsulation efficiency, to be delivered in a sustained manner. Positively charged chitosan (CTS) and negatively charged Eudragit® S100 (ES100) were used as eco-friendly biopolymers. Limonene (LMN) was selected as the model perfume. First, the solution of LMN in ethyl acetate and poloxamer 407 (POX407) in acidic solution was emulsified using ultrasonication. CTS and ES100 were added in that particular order to form o/w emulsion. LMN-loaded microcapsules (LMN-MCs) were prepared by adjusting the pH and freeze-drying for solidification. The electrostatic interactions of CTS and ES100 to form IPECs were highly dependent on pH, changing in the microscopic images of emulsion droplets and zeta potential. The NH₃⁺ group of CTS and the COO^- group of ES100 caused the electrostatic interactions at a specific pH. The formation mechanism of LMN-MCs was successfully validated using instrumental analysis, charge density, and energy dispersive X-ray spectrometer (EDS) mapping. Encapsulation efficiency, loading content, and release rates of LMN-MCs varied according to the ratios of CTS and ES100, demonstrating optimal performance at a 1:1 ratio. The current LMN-MCs could provide a simple manufacturing process with high performance in terms of encapsulation efficiency (>94%), drug loading, yield and sustained release of volatile perfume for 120 h.

X-ray Study of Structural Formation and Thermomechanical Properties of Silver-Containing Polymer Nanocomposites

The structural organization and thermomechanical properties of nanocomposites prepared from interpolyelectrolyte-metal complex (IMC) involving anionic polyelectrolyte, pectin and AgNO₃, and cationic polyelectrolyte, poly(4-vinylpyridine), have been investigated using the methods of wide- and small-angle X-ray scattering and thermomechanical analysis. It is established that chemical reduction of Ag⁺ ions in the IMC by sodium borohydride results in formation of the nanocomposite based on the "pectin-poly(4-vinylpyridine)" interpolyelectrolyte complex (IPEC) and Ag⁰ nanoparticles as well. At the same time, the level of nanocomposites' structural heterogeneity is substantially enhancing, while effective size of the heterogeneity regions decreases. The nanocomposites IPEC-Ag⁰ prepared are shown much bigger T _g value and enhanced ability for deformation than those for IMC.

Polymeric stabilizers for protection of soil and ground against wind and water erosion

The article is devoted to the design, development and application of a new generation of binders for various dispersed systems, including soil, ground, sand, waste rock and others. The binders are formed by interaction of oppositely charged polyelectrolytes, both chemically stable and (bio)degradable. The fundamental aspects of interpolyelectrolyte reactions are discussed; the IPC structure and properties of the resulting interpolyelectrolyte complexes (IPCs) allow considering them as unique and universal binders. Numerous results of laboratory experiments and field trials of the IPC formulations are presented. In particular, large-scale tests have been done in the Chernobyl accident zone where the IPC binders were shown to be effective means to suppress water and wind erosion thereby preventing a spread of radioactive particles (radionuclides) from contaminated sites. Ecologically friendly IPC compositions are described, including those based on commercially available polymers; prospects for improving their efficiency and extending the range of their possible use are discussed.

Constant Electric and Magnetic Fields Effect on the Structuring and Thermomechanical and Thermophysical Properties of Nanocomposites Formed from Pectin-Cu(2+)-Polyethyleneimine Interpolyelectrolyte-Metal Complexes

Applying wide-angle X-ray scattering method, thermomechanical analysis, and differential scanning calorimetry, the structural organization and properties of nanocomposites formed by chemical reduction of Сu(2+) cations in the interpolyelectrolyte-metal complex (pectin-Cu(2+)-polyethyleneimine) under the influence of a constant magnetic and electric fields have been studied. It has been found that the chemical reduction of Cu(2+) cations in the interpolyelectrolyte-metal complex bulk under constant electric and magnetic fields leads to formation of nanocomposite consisting of interpolyelectrolyte complex, including pectin-polyethyleneimine and nanoparticles of the metal Cu phase, whereas nanocomposite with Cu/Cu2O nanoparticles is formed in original state (without any field). It was observed that, under constant field, nanocomposites obtained have higher structural glass-transition temperatures and thermal stability.