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Drug Nanocrystals
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Mayank Singhal, Jouni Hirvonen, Leena Peltonen
Any material at a pressure and temperature above its critical point is a supercritical fluid (SCF). SCFs have high diffusion rates because of their low density and viscosity, which enables rapid mixing for fast precipitation (Girotra et al. 2013). Carbon dioxide is the preferred SCF because it can be easily transformed into the supercritical state as it has near ambient critical temperature (ca. 31°C) and a fairly low critical pressure (73.8 bar). Besides, it is easily available, inexpensive, non-flammable, and nontoxic making it more suitable for commercial use. The solvation ability of SCF can be controlled by manipulating the processing pressure and/or temperature, which affects the precipitation and generation of nanocrystals (Al-Kassas et al. 2017).
Nasal and Pulmonary Drug Delivery Systems
Published in Ambikanandan Misra, Aliasgar Shahiwala, In-Vitro and In-Vivo Tools in Drug Delivery Research for Optimum Clinical Outcomes, 2018
Pranav Ponkshe, Ruchi Amit Thakkar, Tarul Mulay, Rohit Joshi, Ankit Javia, Jitendra Amrutiya, Mahavir Chougule
SCF technology is a single step process which leads to the straight production of respirable particles utilizing supercritical fluids (Figure 4.6a). This method also avoids the use of organic solvent. The use of SCF in this process leads to the not only elimination of drying and harvesting stages but also utilizes a minimum amount of solvent because SCF is in the gaseous state under ambient conditions (Palakodaty, York et al. 1998). The use of SCF also makes this method an environment-friendly, commercially viable, recyclable process. The most commonly used SCF in the pharmaceutical industry is supercritical CO2 because it is safe and inert. The application of this method in pulmonary drug delivery is it can be used to produce particulate systems containing proteins and peptides (Rehman, Shekunov et al. 2004; Chattopadhyay, Shekunov et al. 2007). The added advantage of these respirable particles is better purity and control of crystalline forms (Chow, Tong et al. 2007). In spite of being an attractive option, there is a paucity of literature available on the usage of SCF for generating nanoparticles for pulmonary delivery.
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Published in L.G. Wilson, Lorne G. Everett, Stephen J. Cullen, Handbook of Vadose Zone Characterization & Monitoring, 2018
Eric N. Koglin, Edward J. Poziomek, Mark L. Kram
Recently there has been a great deal of attention paid to the use of supercritical fluid extraction (SFE) for the extraction of total petroleum hydrocarbons (TPHs) and other organics (e.g., PCBs) from contaminated soil. The EPA has recently announced that a laboratory SFE-based method is expected to be approved for routine use in the near future. SFE is similar to conventional solvent extraction techniques except that the solvent used is a supercritical fluid (SCF) instead of a liquid. An SCF is a substance in a condition above its critical temperature and pressure. A pump and heater arrangement is used to maintain the solvent in a supercritical state. At these conditions, the physical properties of the SCF are between those of a gas and those of a liquid. Density and solvent strength (the ability to become miscible with a solute) are like those of a liquid, whereas transport properties and compressibility are like those of a gas. During the extraction, the soluble analytes are partitioned from the bulk sample matrix in the SCF, then swept through a flow restrictor into a collection device which is normally at ambient conditions. The fluids used for SFE are generally gases at ambient conditions and can be vented from the collection device, while the extracted analytes are left behind. The extract can then be analyzed by GC, GC/MS, or other techniques.
Development of nanoparticles for pharmaceutical preparations using supercritical techniques
Published in Chemical Engineering Communications, 2022
Tariqul Islam, Abdullah Al Ragib, Sahena Ferdosh, A. B. M. Helal Uddin, Md. Jahurul Haque Akanda, Md. Abdur Rashid Mia, Reddy Prasad D. M, Bin Yunus Kamaruzzaman, Md. Zaidul Islam Sarker
In the NP production process, cost management is a significant aspect, and the process depends partly upon the kind of fluid. In this respect, scCO2 costs comparatively less than other nontoxic, non-flammable, and microbial inactivation fluids. It has a distinctive character that may increase solubility and enhance liquid density; it also exhibits gas-like viscosity (Soh and Lee 2019). SCF technology is widely used for the extraction of bioactive compounds in the field of phytomedicine and natural product science by improving the solubility of essential oils, plant active ingredients, nonpolar compounds, and biopolymers (low molecular weight) using CO2 fluid. scCO2 is well known as a solvent by scientists and researchers due to the conversion of supercritical conditions at a lower temperature (De Melo et al. 2014; Sharif et al. 2014; Del Valle 2015).
Intensification methods of supercritical drying for aerogels production
Published in Drying Technology, 2020
Natalia Menshutina, Pavel Tsygankov, Illarion Khudeev, Artem Lebedev
Supercritical fluids (SCF) are a state of compounds in which the difference between coexisting liquid and vapor phases disappears.[1,2] Any compound at a temperature and pressure above the critical point is regarded as a supercritical fluid. The properties of supercritical fluids are intermediate between of a typical gas and typical liquid properties. So, the SCF has a high density close to the liquids and low viscosity as the gases. The diffusion coefficient in this case is intermediate between the liquid and the gas.[3] The supercritical fluids can be used as substitutes for organic solvents in laboratory and industrial processes.[4] Supercritical fluids are consistent with the basic principles of green chemistry.[5,6] The use of supercritical fluids for a number of chemical and technological problems allow us to maximize the yield of the target product and minimize the production waste. Renewable, environmentally friendly materials are involved in supercritical processes. Among the variety of supercritical fluids, supercritical water and supercritical carbon dioxide are most prevalent as they offer a wide range of possibilities.
Preparation and optimization of Vitamin E acetate liposomes using a modified RESS process combined with response surface methodology
Published in Particulate Science and Technology, 2020
Zhen Jiao, Sai Han, Weifang Wang, Junying Song, Jiangrui Cheng
Supercritical fluids (SCF) exist the homogeneous phase while the pressure and temperature are separately surpassing critical values of fluids. Benefit from the properties like nontoxicity, relative low critical temperature and pressure, high diffusivity, and low viscosity (Zhong et al. 1998; Weinstein et al. 2007; Yamini et al. 2012) supercritical carbon dioxide (SC-CO2) has been widely used as an environmentally friendly alternative solvent to replace organic solvents in many fields (Beckman 2004; Duan et al. 2013; Li et al. 2013; Zhao and Zhang 2014; Khansary et al. 2015; Dwi et al. 2016) including the preparation of liposomes (Karn et al. 2013; Xu, Zhao, and He 2015). The processes based on SC-CO2 are carried out under mild conditions. Therefore, it can effectively protect the activity of thermosensitive substances during the processes. In addition, carbon dioxide is gaseous at room temperature and atmospheric pressure, resulting in a less residual solvent in the final product.