Rapid Expansion Of Supercritical Fluids Research Articles

Dry-Coating of Powder Particles is Current Trend in Pharmaceutical Field

Modification of surface attributes of particles, usually accomplished by coating, is desirous to enhance and maintain their usability. Coating is a multi-step process involves application of the coating material (CoM) onto the substrate, herein powder particles, where the process along with device/ equipment monitors surface attributes of the applied coating. Nowadays competitive market calls for cost cutting to survive product(s). Thus saving of energy and time, minimising number and quantity of additives, reducing and shortening process steps; consequently minimising the coating process cost are main goals while developing coating process for powder particle. Innovation of processes for dry-powder coating (DPC) along with their further development and refinement finds solution to said issues. Further, DPC process does not calls for liquid solvent or solution thus are viewed as cost-effective and environmentally safe, DPC process uses thermo-mechanical methods like mechanofusion, magnetic assisted impaction coating (MAIC), hybridization, rotating fluid-bed process, theta-composer, hot-melt coating (HMC), and many others. Besides these available are non-thermo-mechanical methods namely electrostatic coating; supercritical fluids (SCF) based methods like rapid expansion of supercritical fluid (RESF), gas anti-solvent (GAS), SCF anti-solvent, gas-saturated solution (GSS); vapour coating; and others. Basing on said thermo-mechanical and non-thermo-mechanical principle several DPC methods/ process had been reported in scientific literatures and patents. Said DPC method founds multidisciplinary applications like drug delivery and drug development. Diverse devices are there for the DPC process; their method of working, principle, limitations and benefits along with their applicability in pharmaceutical field are discussed and presented in this article.
 Keywords: Dry, particle, coating, pharmaceutical, process

Investigation on hydrodynamic and formation of nano particle by RESS process: The numerical study

The particle formation by supercritical technology is an active research field. Rapid expansion of supercritical fluid (RESS) is a promising new technology for particle formation using supercritical fluids. In this study, numerical modeling of particle formation of TBTPP (5, 10, 15, 20-tetrakis (3, 5-bis (trifluoromethyl) phenyl) porphyrin) through RESS process is investigated. The RESS process contains two pre-expansion (nozzle part) and expansion vessel (supersonic free jet) parts. In the first section, mass, momentum and energy balances in addition to extended generalized Bender equation of state (egB-EoS) as accurate equation of state is used to calculate temperature, pressure, density and velocity of supercritical carbon dioxide (SC-CO2) based on mathematical modeling and computational fluid dynamics (CFD) simulation methods. Both models include friction in the nozzle and heat exchange in the expansion vessel and in the nozzle region. Using calculated pressure and temperature, the solubility of TBTPP in the supercritical CO2 is predicted by Peng-Robinson EoS with Kwak-Mansoori mixing rule and the results are compared with experimental data and a semi-empirical correlation. Supersaturation, homogenous nucleation and critical radius of TBTPP based on classical nucleation theory are calculated. The effect of pre-expansion temperature on supersaturation, nucleation and critical radius parameters is also studied. The results of hydrodynamic and particle formation modeling present the same trend as reported in the literature.

A novel method for food particle production using subcritical water extraction: Ganoderma mushroom as a case example

In recent years, supercritical fluid-based technologies have been used for the production of food particles as well as the extraction. These methods are used in particle generation as well as extraction due to properties of solvent such as having good dissolving and diffusing power, moderable conditions, capability to produce particles with a regular particle size distribution of the solvent and being environmentally friendly. Recently, three different techniques named rapid expansion of supercritical fluid (RESS), supercritical anti solvent application (SAS) and particle formation with gas-saturated solvent (PGSS) are used for particle generation. In this study, a novel system capable of doing subcritical water extraction and particle formation was briefly introduced. The system was based on first hydrothermal extraction of target compound, then transition of saturated extract solution into fine particles at underflow in hot air assistance. Ganoderma lucidum mushroom was used as working material to investigate process parameters. Also, extract composition and structure were identified.

Rapid Expansion of Supercritical Fluids for Particle Formation from Pharmaceutical Compounds: A Review

The rapid expansion of supercritical solution (RESS) is a promising method for particle formation. In this paper, general review of fundamental and available results from studies of particle formation by RESS process using carbon dioxide as a solvent for pharmaceutical compounds.

Characterization of Carbamazepine-Loaded Solid Lipid Nanoparticles Prepared by Rapid Expansion of Supercritical Solution

Purpose: To prepare carbamazepine-loaded solid lipid nanoparticles (CBZ-SLN) for prolonged release of CBZ in oral drug delivery.Methods: CBZ-loaded SLNs were prepared by rapid expansion of supercritical solution (RESS). SLNs were formulated using stearic acid as the lipid component. Initially, lipid and drug were separately micronized by RESS process separately. This was followed by co-precipitation of the components with the two solutes using RESS to produce drug-loaded SLNs. The formulations were characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM) and ultraviolet spectrophotometry (UV).Results: Application of RESS to pure stearic acid yielded spherical particles in the range 40 to 200 nm which was about 600 times smaller than the unprocessed powder based on SEM observation. Similarly, RESS processing of carbamazepine produced nanoparticles with rod shape. FT-IR analysis showed that no chemical structure change occurred during RESS processing of both components. Coprecipitation of drug and lipid using RESS produced SLNs with drug loading capacity of 2.2 %. RESS yielded ultrafine spherical particles (100 nm) of CBZ-SLNs.Conclusion: The successful preparation and characterization of carbamazepine-loaded solid lipid nanoparticles by RESS as well as their characterization has been achieved in this study.Keywords: Rapid expansion of supercritical fluid, Stearic acid, Solid lipid nanoparticles, Carbamazepine, Co-precipitation

Modeling and calculation of the process of rapid expansion of supercritical fluid yielding nanoparticles

A mathematical model is proposed and the calculation is carried out for the process of rapid expansion of the supercritical fluid containing a dissolved solid compound via a capillary into a volume with specified temperature and pressure. The analysis of sensitivity of the model toward the process parameters makes it possible to choose the most important parameters for producing nanoparticles with preset properties and dimensions. The calculations demonstrate that all the parameters of the expansion process under study have a particular effect on the size of the particles being formed.

The Breadth and Intensity of Supercritical Particle Formation Research with an Emphasis on Publication and Patent Disclosures

The drawbacks of the conventional mechanical treatments for particle micronization often resulting in product damage or performance degradation have highlighted the need for alternative particle formation processes. The aim of this study was to shed light on the trends of the scientific studies and innovations in the field of particle formation using supercritical fluids (SCF) in order to observe the progress of science and technology and to satisfy the need for a global view of research activities. The publications in the ISI Web and the patents in a patent database were screened using nine different keywords in title or topics. A total of 939 journal publication and 206 patent disclosures between 1980−2009, with the contributions of 3588 authors and 604 innovators, were found to focus on particle formation using SCF. The results showed that the majority of the publication (59.2%) and patent (40.3%) disclosures were related to antisolvent precipitation and rapid expansion of SCF (18.3, 16%). Patents orig...

Fabrication of fine microcapsulated red phosphorus particles by SCF-RESS with a new structure nozzle

A novel process of preparing microencapsulated red phosphorus particles by rapid expansion of supercritical fluids (RESS) was tested, in which a new kind of nozzle and supercritical CO2 as a solvent were used. The structure of the microencapsulated red phosphorus particles were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). These results show that red phosphorus particles can be effectively encapsulated with paraffin by using the method. At the same time, how the moisture absorption ratio of microencapsulated red phosphorus particles was dependent on the experimental conditions was further investigated. The results suggest that paraffin-microencapsulated red phosphorus particles show a lower moisture absorption ratio within the experimental conditions of the extraction column and nozzle temperature of 120°C, extraction column pressure of more than 16 MPa, and a mass flow of core particles (0.5 g/min).

Micronization of salicylic acid and taxol (paclitaxel) by rapid expansion of supercritical fluids (RESS)

The particle sizes of the pharmaceutical substances are important for their bioavailability. The bioavailability can be improved by reducing the particle size of the drug. In this study, salicylic acid and taxol were micronized by the rapid expansion of supercritical fluids (RESS). Supercritical CO 2 and CO 2 + ethanol mixture were used as solvent. Experiments were carried out to investigate the effect of extraction temperature (318–333 K) and pressure (15–25 MPa), pre-expansion temperature (353–413 K), expansion chamber temperature (273–293 K), spray distance (6–13 cm), co-solvent concentration (ethanol, 1, 2, 3, v/v, %) and nozzle configuration (capillary and orifice nozzle) on the size and morphology of the precipitated salicylic acid particles. For taxol, the effects of extraction pressure (25, 30, 35 MPa) and co-solvent concentration (ethanol, 2, 5, 7, v/v, %) were investigated. The characterization of the particles was determined by scanning electron microscopy (SEM), optical microscopy, and LC–MS analysis. The particle size of the original salicylic acid particles was L/D: 171/29–34/14 μm/μm. Depending upon the different experimental conditions, smaller particles (L/D: 15.73/4.06 μm/μm) were obtained. The particle size of taxol like white crystal powders was reduced from 0.6–17 μm to 0.3–1.7 μm The results showed that the size of the precipitated salicylic acid and taxol particles were smaller than that of original particles and RESS parameters affect the particle size.

Coating of magnesium powder by rapid expansion of supercritical solution method

In order to solve the reserve stability problem of pyrotechnic explosives containing magnesium powder, a coating method named rapid expansion of supercritical fluid is studied. Continuous coating film of paraffin can be formed on the surface of magnesium powder when paraffin content is about 1.5%. Humidity resistance property of the coated magnesium is promoted obviously. The flame sensitivity of the coated magnesium is 4.8% lower than that of the original magnesium powder after mixed with oxidant. The burning velocity of the coated magnesium is 4.7% lower than that of the contrastive sample. This method may be used to enhance the reserve stability problem of pyrotechnic explosives and the safety of magnesium powder modifying process.

Formation of composite drug–polymer particles by co-precipitation during the rapid expansion of supercritical fluids

In modern medicine oral application of solid forms is the preferential way. Thus, in pharmaceutical applications size, shape and morphology of the solid particles are important because they can affect the bioavailability of drug particles. Since the bioavailability of orally applied drugs depends on the rate of dissolution and absorption, methods to increase the rate of dissolution are often necessary to reach significant blood levels. A promising way to increase the dissolution rate is the reduction of particle size. Recent investigations show, that the rapid expansion of supercritical solutions (RESS) enables the formation of submicron particles of thermally labile drugs and dissolution studies demonstrate that submicron drugs are characterized by a significantly higher dissolution rate. However, active ingredients in the micro- or sub-micro range are very difficult to be included in solid dosage forms. To overcome this, the co-precipitation during the rapid expansion of supercritical solutions (CORESS) was used to produce composite particles. In CORESS both, the drug and the biodegradable polymer are dissolved in supercritical CO 2, followed by the rapid expansion of the ternary mixture. This leads to the simultaneous co-precipitation of the solutes, resulting in the different morphologies and composition profiles for the composite particles. In the present work, the micronisation of two pure polymers by RESS and the formation of composite l-poly(lactic acid)–phytosterol particles formed by CORESS were investigated. These experiments showed the feasibility of CORESS to enable the formation of submicron composite particles with different solutes. Prior to the CORESS-experiments, the phase behaviour of CO 2/phytosterol and of CO 2/ l-poly(lactic acid) were investigated. The melting temperature of the pure solutes under CO 2 pressure and the solubility of phytosterol in CO 2 were also measured.

Molecular dynamics studies on clustering process of solute molecules through rapid expansion of supercritical fluids

The expansion of a supercritical fluid (SCF) solution composed of CO 2 and naphthalene from 10 to 1 MPa has been simulated by using both the conventional NVT-MD and one-dimensional pressure-control molecular dynamics (OPC-MD) methods. The characteristic pressure corresponding to a significant decrease in density of the SCF solution (about 6 MPa) is lower than that of pure CO 2 (about 8 MPa) due to the strong attractive interactions of NAP molecules with CO 2 molecules. The solute clusters dispersed in the SCF start to grow at the characteristic pressure by uniting small clusters to form a larger cluster and gathering dispersed solute molecules to the cluster. In the solute clusters, the number of CO 2 molecules gradually decrease as the clusters grow, though the number is still comparable to that of solute molecules at 1 MPa, suggesting that remaining CO 2 molecules will escape from the solute clusters at lower pressures.

Potentials and prospects for application of supercritical fluid technology in bioprocessing

Recent investigations on the application of supercritical (SC) fluid technology in bio- and food chemistry are reviewed. The gas-antisolvent crystallization and rapid expansion of SC fluid emerge as attractive methods for micron-size particle formation. Also gaining ground is enzymic catalysis in SC CO 2, which offers the possibility of integrated synthesis-product recovery processes. These processes, successfully tested on a laboratory scale, need further scale-up and optimization. Supercritical CO 2 has proven to be unfriendly, or even toxic, for living microorganisms, which precludes direct fermentation in dense CO 2 but does not rule out other useful applications.

Potentials and Prospects for Application of Supercritical Fluid Technology in Bioprocessing

Recent investigations on the application of supercritical (SC) fluid technology in bio- and food chemistry are reviewed. The gas-antisolvent crystallization and rapid expansion of SC fluid emerge as attractive methods for micron-size particle formation. Also gaining ground is enzymic catalysis in SC CO2, which offers the possibility of integrated synthesis-product recovery processes. These processes, successfully tested on a laboratory scale, need further scale-up and optimization. Supercritical CO2 has proven to be unfriendly, or even toxic, for living microorganisms, which precludes direct fermentation in dense CO2 but does not rule out other useful applications.