Pressure-induced amorphization and existence of molecular and polymeric amorphous forms in dense SO2.

We report here the pressure-induced amorphization and reversible structural transformation between two amorphous forms of SO2: molecular amorphous and polymeric amorphous, with the transition found at 26 GPa over a broad temperature regime, 77 K to 300 K. The transformation was observed by both Raman spectroscopy and X-ray diffraction in a diamond anvil cell. The results were corroborated by ab initio molecular dynamics simulations, where both forward and reverse transitions were detected, opening a window to detailed analysis of the respective local structures. The high-pressure polymeric amorphous form was found to consist mainly of disordered polymeric chains made of three-coordinated sulfur atoms connected via oxygen atoms, with few residual intact molecules. This study provides an example of polyamorphism in a system consisting of simple molecules with multiple bonds.

[Antineoplastic mechanisms of niclosamide-loaded nanoparticles in human colorectal cancer cells]. / Molekuliarnye mekhanizmy protivoopukholevoi aktivnosti polimernoi formy niklozamida v otnoshenii kletok kolorektal'nogo raka.

Using poly(lactic-co-glycolic) acid we developed a polymeric form of niclosamide (PFN) and investigated molecular mechanisms underlying its antitumor activity against human colorectal cancer cell lines (SW837, Caco-2, COLO 320 HSR). PFN was shown to be more cytotoxic against cancer cells and less cytotoxic against normal cells (human embryonic lung fibroblasts) as compared to niclosamide. Both niclosamide and its polymeric form caused mitochondrial damage (evaluated as a decrease in rhodamine 123 accumulation) and increased the levels of reactive oxygen species, particularly mitochondrial superoxide, resulting in the oxidative damage to biomolecules. Furthermore, niclosamide and PFN induced G0/G1 cell cycle arrest.