Supercritical fluid technology nanoparticles

Gupta, R.B. (2006). Supercritical fluid technology for particle engineering. In Nanoparticle Technology for Drug Delivery, R.B. Gupta and U.B. Kompella (eds.). Informa Healthcare. New York, 53-84. 

Scheme 7 (A) Schematic of the process of producing nanoparticles using supercritical fluid technology. See, for example. Ref. 73.

Byrappa K, Ohara S, Adschiri T. Nanoparticles synthesis using supercritical fluid technology -towards biomedical applications. Adv Drag Deliv Rev 2(X)7 60 299-327. 

Kompella UB, Koushik K. Preparation of drug delivery systems using supercritical fluid technology. Crit Rev Ther Drug 2001 18 173-199. Reverchon E. Supercritical antisolvent precipitation of micro- and nanoparticles. J Supercrit Fluid 1999 15 1-21. 

A number of interesting properties are associated with the critical state. One of these is that the density of the liquid and of the vapor becomes identical, and for this reason the interface between the two phases disappears. Supercritical fluid technology is a relatively new approach to obtain micro- and nanoparticles. For pharmaceutical applications, supercritical carbon dioxide (SC-CO2) is most widely used because of its low and easily accessible critical temperature and pressure (31.2 °C ... 

Varshosaz J, Hassanzedh F, Mahmoudzadeh M, Sadeghi A (2009) Preparation of cefuroxime axetil nanoparticles by rapid expansion of supercritical fluid technology. Powder Technol 189(1) ... 

Ibuprofen is a nonsteroidal anti-inflammatoiy drug (NSAID) used for pain relief due to the anti-inflammatory effects [56], however this drug has low solubility in aqueous solutions [57, 58], which implies involvement in negative absorption by the body. Then researchers are using supercritical fluid technology to overcome these drawbacks. Antonov et al., [59] studied the solubility of ibuprofen in supercritical CO2 by fourier transform infrared spectroscopy, moreover ibuprofen was also studied in supercritical impregnation processes polymers [60, 61], in theoretical RESS process [62, 63] and experimentally for micronization of particles with reductions from 45 pm to 2.85 pm [64], and formation of even smaller nanoparticles by RESOLV [65]. Furthermore, Molnar et al., [66] studied the enantioseparation of racemic ibuprofen in SFE and realized that the system pressure of the extraction is directly related to resolution efficiency. 

Nanocapsules act like a reservoir, which are called vesicular systems. They carry the active substance entrapped in the solid polymeric membrane or on their surfaces. The cavily inside contains either oil or water. A schematic diagram of Polymer Nanocapsules is shown in Fig. 9.2 [5], There are different methods that are used nowadays to prepare polymeric nanoparticles, such as nanoprecipitation (also termed as the solvent diffusion and solvent displacement method), solvent evaporation, dialysis, microemulsion, surfactant-free emulsion, salling-out, supercritical fluid technology, and interfacial polymerization [2]. Among these methods, nanoprecipitation is a fast and simple process, which does not require a pre-prepared polymer emulsion before the nanoparticle preparation. It produces a dispersion of nanoparticles by precipitation of preformed hydrophobic polymer solution. Under... 

The most important limitation of RESS is the low solubility of compounds in supercritical fluids and the use of co-solvent to improve solubility is usually costly and not economically feasible. As an alternative a supercritical fluid anti-solvent (SAS) process was introduced where a supercritical fluid is used to cause substrate precipitation or recrystallization from a polar liquid solvent (Subramaniam et ah, 1999). Zhong et ah (2008) successfully used SAS to produce alcohol soluble zein micro- and nanoparticles. A number of other technologies based on manipulating supercritical fluids have been successfully used to produce nanoparticles (Della Porta and Reverchon, 2008 Matsuyama et ah, 2003 Meziani and Sun, 2003 Shariah and Peters, 2003 Subramaniam et ah, 1999). 

Gallagher PM, Coffey MP, Krukonis VJ, Klasutis N. Gas anti-solvent recrystallization new process to recrystallize compounds insoluble in supercritical fluids. In Johnston KP, Penniger JML, eds. Supercritical Fluid Science and Technology. Washington, DC American Chemical Society, 1989 334-354. Dixon D, Johnston KP, Bodmeier R. Polymeric materials formed by precipitation with a compressed fluid antisolvent. AIChE J 1993 39 127-136. Chattopadhyay P, Gupta RB. Production of griseofulvin nanoparticles using supercritical CO2 antisolvent with enhanced mass transfer. Int J Pharm 2001 228 19-31. 

The use of supercritical fluids as alternatives to organic solvents is revolutionising a huge number of important science areas (24). Scientific applications vary from established processes, such as the decaffeination of coffee and the extraction and synthesis of active compounds, to the destruction of toxic waste in supercritical water, the production of nanoparticles and new materials, to novel emerging clean technologies for chemical reactions and extraction. 

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