Dynamic and static characteristics of drug dissolution in supercritical CO₂ by infrared spectroscopy: Measurements of acetaminophen solubility in a wide range of state parameters

In this work we use infrared spectroscopy to investigate solubility properties of a bioactive substance in supercritical CO2 (scCO2). By using acetaminophen as a model compound, we show that the method can provide high sensitivity that makes it possible to study solubility at small concentrations, up to 10–6 mol·L–1. This method also allows one to investigate the kinetics of the dissolution process in supercritical solvent. Our measurements at two different points of the (p,T) plane ((40 MPa, 373 K) and (40 MPa, 473 K)) have shown significant difference in the kinetic mechanisms of acetaminophen dissolution at these two states: at higher temperature the dissolution process in scCO2 has two steps: (i) “fast” step when the acetaminophen concentration in scCO2 quickly reaches (70 to 80) % of the saturation level and (ii) a subsequent “slow” step where the acetaminophen concentration slowly increases up to the saturation level. However, at lower temperature, the dissolution process has only one, “slow” step

Spectroscopic characterization of single co-crystal of mefenamic acid and nicotinamide using supercritical CO2

The present study explores the possibility to synthetize, using supercritical fluid, single crystal of co-crystal formed by mefenamic acid as active pharmaceutical ingredient and nicotinamide as a co-former. The growth of single crystals is important for the determination of co-crystal structure and in particular, for the ones whose unit cells contain a large number of atoms, it becomes crucial. For this purpose, we analyzed the effect of temperature, solid mixture composition and time duration of the co-crystallization process on the synthetized solid. The structure of the latter was determined using single-crystal X-ray diffraction while the composition of fine powders and the intermolecular interactions involved in their synthesis were analyzed using powder X-ray diffraction and diffuse reflectance infrared Fourier transform spectroscopy respectively. Our results show that the single crystal of mefenamic acid and nicotinamide co-crystal is synthetized for the first time in supercritical CO2 at 90 °C, 193 bars and a time duration of three weeks

Astrobiology and the possibility of life on Earth and elsewhere…

Astrobiology is an interdisciplinary scientific field not only focused on the search of extraterrestrial life, but also on deciphering the key environmental parameters that have enabled the emergence of life on Earth. Understanding these physical and chemical parameters is fundamental knowledge necessary not only for discovering life or signs of life on other planets, but also for understanding our own terrestrial environment. Therefore, astrobiology pushes us to combine different perspectives such as the conditions on the primitive Earth, the physicochemical limits of life, exploration of habitable environments in the Solar System, and the search for signatures of life in exoplanets. Chemists, biologists, geologists, planetologists and astrophysicists are contributing extensively to this interdisciplinary research field. From 2011 to 2014, the European Space Agency (ESA) had the initiative to gather a Topical Team of interdisciplinary scientists focused on astrobiology to review the profound transformations in the field that have occurred since the beginning of the new century. The present paper is an interdisciplinary review of current research in astrobiology, covering the major advances and main outlooks in the field. The following subjects will be reviewed and most recent discoveries will be highlighted: the new understanding of planetary system formation including the specificity of the Earth among the diversity of planets, the origin of water on Earth and its unique combined properties among solvents for the emergence of life, the idea that the Earth could have been habitable during the Hadean Era, the inventory of endogenous and exogenous sources of organic matter and new concepts about how chemistry could evolve towards biological molecules and biological systems. In addition, many new findings show the remarkable potential life has for adaptation and survival in extreme environments. All those results from different fields of science are guiding our perspectives and strategies to look for life in other Solar System objects as well as beyond, in extrasolar worlds